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AUDE 5310 Embryology & Genetic Conditions > Final Exam > Flashcards

Final Exam Flashcards

1
Q

what are characteristics of AD inheritance

A

Vertical Transmission
■ 50% chance of offspring inheriting per pregancy
■ NO carriers
■ All affected individuals are heterozygous
■ Only ONE bad gene is needed to inherit
■ EX: Waardenburgs Syndrome

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2
Q

what is an ex of ad inheritance

A

waardenburgs syndrome

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3
Q

what is AR mode of inheritance

A

Horizontal transmission
■ 25% chance of offspring inheriting per pregancy
■ BOTH parents must be obligate carriers
■ Consanguinity is common
■ EX: Usher’s Syndrome

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4
Q

what is an ex of AR inheritance

A

usher’s syndrome

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5
Q

what are two characteristics of x linked inheritance

A

NO FATHER TO SON TRANSMISSION
abnormal gene is called on x chromosome

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6
Q

what are characteristics of x linked recessive

A

dad has it: 100% chance daughter is carrier, 0% son will
mom has it: 50% chance son will carry trait, 50% chance son will have trait, 50% daughter carries the trait

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7
Q

what are examples of x linked recessive inheritance

A

colorblindness, hemophilia muscular dystrophy

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8
Q

what are characteristics of x linked dominant

A

dad has it: 100% chance daughter is carrier or expresses, 0% chance son will
mom has it: 50% chancer per offspring

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9
Q

what is an example of x linked dominant

A

alport’s syndrome

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10
Q

what are characteristics of y linked inheritance

A

male to male transmission only
100% transmission to male offspring

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11
Q

what are characteristics of mitochondrial gene

A

100% risk of transmission to offspring (M&F)
only transmitted from the mother

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12
Q

what is another term for mitochondrial disorder

A

eve gene

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13
Q

what is an example of mitochondrial inheritance

A

aminoglycoside ototoxicity

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14
Q

what is the most common AR deafness condition

A

Usher’s

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15
Q

what is the second most common AR deafness condition

A

Pendred’s

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16
Q

what is the third most common AR deafness condition

A

JLNS

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17
Q

what are the most common autosomal dominant syndromic HL

A

Waardenburg
BOR

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18
Q

what are the most common autosomal recessive syndromic HL

A

Usher’s
Pendred’s
JLNS

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19
Q

syndromic disorders show abnormalities in

A

many areas

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20
Q

how are nonsyndromic loci named

A

according to their inheritance pattern

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21
Q

DFNA

A

AD

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22
Q

DFNB

A

AR

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23
Q

DFNX

A

X linked

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24
Q

DFNY

A

Y linkedj

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25
Q

DFNM

A

Modifier

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26
Q

AUNA

A

auditory neuropathy

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27
Q

OTSC

A

otosclerosis

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28
Q

Responsible for 50-80% of all AR HL

A

Connexin 26

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29
Q

protein found in the OHC and causes motility of them

A

Prestin

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30
Q

single gene mutations

A

monogenic conditions

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31
Q

many genes causing the same phenotype

A

Genetic heterogeneity

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32
Q

what is a characteristic/hallmark of chromosomal abnormalities?

A

intellectual disability

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33
Q

what are the branchial arch disorders

A

treacher collins
pierre robins
Sticklers

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34
Q

What are the characteristics of treacher collins

A

large fish mouth from poorly developed muscles
abnormal external ear (peanut ear)
small lower jaw

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35
Q

what are the characteristics of stickler’s syndrome

A

small lower jaw
cleft palate
tongue placed further back in the mouth
otitis media & CHL

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36
Q

why does sticklers have a conductive loss

A

ear canals, ossicles pinna & ME cavity form from the 1st & 2nd arches

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37
Q

what are the characteristics of pierre robin’s syndrome

A

near sightedness (myopia)
retinal detachment
CHL or mixed HL
arthritis at early age
underdevelopment of middle of face & small lower jaw

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38
Q

what happens in the pre embryonic period (fertilization to 3rd week)

A

3 germ layers form

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39
Q

what happens in the embryonic period (3-8th week)

A

organogenesis

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40
Q

what happens in the fetal period (9wks to birth)

A

maturing of tissues/organs

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41
Q

what is a phenocopy

A

environmentally caused trait that mimics a genetically determined trait
thalidomide is phenocopy of phocomelia
hair loss from chemo is phenocopy of alopecia

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42
Q

what is pleitropy

A

diverse effects of 1 gene/gene pair on several organ systems & fxns resulting in multiple phenotypic effects on the body
marfan’s syndrome

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43
Q

what is hemizygous

A

1 chromosome of the pair is present instead of the two
males due to XY

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44
Q

How to read 1q2_4

A

Chromosome 1, long arm q, band 2 region 4

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45
Q

what is epidemiology and why study it

A

Study of population health
To help understand the incidence of a certain disorder

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46
Q

what are modifier genes

A

affect phenotypic outcome of a given genotype by interacting in the same or in parallel biological pathway as the disease gene

modulate expressivity (severity), penetrance, age of onset, progression of disease, or pleiotropy

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47
Q

these are the common source of phenotypic variation in human populations

A

modifier genes

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48
Q

what is gene mapping

A

identification of approximate or exact location of a gene ona chromosome

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49
Q

what is gene cloning

A

production of exact copies of a particular gene or dna sequence

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50
Q

how does gene cloning happen

A

DNA extracted from an organism contains all of its thousands of different genes
The genetic engineer must find the one specific gene that encodes the specific protein of interest

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51
Q

what is inner ear homeostasis

A

process which chemical equilibrium of inner ear fluids & tissues is maintained

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52
Q

causes 50-80% of all AR genetic HL

A

connexin

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53
Q

Increased K+ transport in the endolymph or increased endolymph production

A

endolymphatic hydrops

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54
Q

what is an example of endolymphatic hydrops

A

meniere’s disease

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55
Q

Decreased K+ transport in the endolymph or decreased endolymph production

A

endolymphatic xerosis

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56
Q

what is an example of endolymphatic xerosis

A

connexin 26

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57
Q

what is connexin 26

A

gene mutation results in abnormal connexin gap junction proteins

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58
Q

protein found in the OHC and causes motility of them

A

prestin

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59
Q

what is heterogeneity

A

many genes causing the same phenotype
ex: hl

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60
Q

prelingual

A

Born w/ deafness, before learning language
Congenital HL

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61
Q

postlingual

A

Deaf after learning language

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62
Q

Hallmark of chromosomal disorders is

A

intellectual disability

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63
Q

Multiple genes involved, multiple systems affected, whole ____ abnormalities

A

chromosomal disorders

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64
Q

Branch of genetics that studies structure and function of the cell, especially the chromosomes

A

cytogenetics

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65
Q

worldwide disease

A

pandemic

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66
Q

one area that has a particular condition more than other areas in the world

A

endemic

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67
Q

caused by a mutation of a single gene and broadly classified by mode of inheritance

A

mendelian/monogenic

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68
Q

what is multifactorial disorder

A

traits that result from a combination of multiple environmental factors with multiple genes

OAV

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69
Q

what is polygenic disorder

A

traits/diseases caused by the impact of different genes & each gene has a small impact on the phenotype
spina bifida, cleft lip/palate, HL

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70
Q

what is a spontaneous mutation

A

genetic change resulting from mis pairing of bases during replication (not inherited)
can be due to environmental influences
Genetic changes that result from normal cell processes

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71
Q

what are missense mutations

A

conservative & non conservativew

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72
Q

what are point mutations

A

silent, nonsense, missense (conservative 7 nonconservative)

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73
Q

what is a conservative mutation

A

mutation that ends w/ different protein product but no phenotypic change

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74
Q

what is non conservative mutation

A

mutation & ends w/ different protein product that is too different that cannot have the same fxn the protein was supposed to do

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75
Q

what is a silent mutation

A

mutation but ends with the same protein that was originally coded

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76
Q

what is a nonsense mutation

A

causes a stop protein and truncated proteins

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77
Q

what is anticipation

A

worsening of symptoms of genetic disease from 1 generation to the next

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78
Q

what is allelic expansion

A

increase in bases that increases gene size

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79
Q

what is an example of anticipation & allelic expansion

A

Huntingdon’s disease

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80
Q

what is huntingdon’s disease and inheritance

A

AD
adult onset
loss of muscle coordination & control
deterioration of intellectual fxn
early death
Seen in Ash jews most

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81
Q

what are chromosomal abnormalities

A

WHOLE chromosomal disorder
have adverse affects on many systems/structures

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82
Q

How many chromosomal abnormalities can make it to term?

A

Only 3 autosomal, 1 sex linked monosomy (Turner Syndrome)

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83
Q

monosomy

A

missing a chromosome of the two
lethal

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84
Q

trisomy

A

addition of a chromosome
21
18
13
X

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85
Q

what is trisomy 21

A

downs

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86
Q

what is trisomy 18

A

edwards

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87
Q

what is trisomy 13

A

patau

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88
Q

what is trisomy x

A

Klinefelter’s

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89
Q

Nullisomy

A

no chromosome pair
lethal

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90
Q

aneuploidy

A

in somatic cells
abnormal # of chromosomes
mono, tri, & nullisomy
21, 18, 13 are most common

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91
Q

how does aneuploidy occur

A

during cell division when chromosomes do not separate equally between two daughter cells

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92
Q

what is genomic imprinting and examples

A

process in which the phenotype differs depending upon which parent transmits a particular allele or chromosome
prader willi
angelman

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93
Q

prader willi syndrome

A

Paternal origin
deletion of 15 hromosome
uncontrollable eating, intellectual disability, infertility

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94
Q

angelman syndrome

A

maternal origin
deletion of 15 chromosome
uncontrollable laughing, gait ataxia, intellectual disability

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95
Q

Subcentric or submetacentric

A

The chromosome’s p & q arms’ lengths are unequal

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96
Q

Metacentric

A

The two arms of chromosome are roughly equal in length

97
Q

telocentric

A

Centromere is located at the terminal end of the chromosome
Not present in humans

98
Q

holocentric

A

Entire length of the chromosome acts as the centromere
Found in worms (nematodes); not present in humans

99
Q

homologous

A

same chromosomes

100
Q

heterozygous

A

different genes

101
Q

homozygous

A

same identical gene

102
Q

What is the general phenotype of people with chromosomal abnormalities

A

more than 2 systems involved and intellectual disabilities and abnormal growth patterns

103
Q

where do we see ring chromosomes

A

acrocentric chromosomes

104
Q

what is a ring chromosome

A

both arms of a chromosome break and the broken ‘sticky’ ends fuse at the breakage points. The broken fragments are lost and with them any genes they may contain

105
Q

what are the ring chromosomes

A

r13, r14, r15, r21, r22 (acrocentrics)

106
Q

what are the 3 ways down’s can occur

A

nondisjunction
RT
mosaicism

107
Q

what is nondisjunction

A

95% of down’s
As the embryo develops, the extra chromosome is replicated in every cell of the body and accounts for an extra chromosome 21
the failure of the chromosomes to separate, which produces daughter cells with abnormal numbers of chromosomes

108
Q

what is robertsonian translocation

A

4% of down’s
chromosomes break at their centromeres and the long arms fuse to form a single chromosome with a single centromere
The short arms also join to form a reciprocal product, which typically contains nonessential genes and is usually lost within a few cell divisions
Centromeres break and the long arms fuse → short arms fuse to form a new chromosome → new small chromosomes go away after few cell cycles → end result has new balanced chromosome with all the genetic information needed

109
Q

what chromosomes are usually seen with RT

A

acrocentric
13, 14, 15, 21, 22

110
Q

When long arm of 21 translocates with chromosome 14 (or 15)

A

Heterozygous carrier is phenotypically normal/balanced

111
Q

If mother is RT carrier, risk of 2nd trisomy 21 pregnancy is

A

10-15%

112
Q

what is mosaicism

A

1% down’s
Presence of two or more cell lines (cell populations) that differ genetically in an individual or tissue but that are derived from a single zygote
some cells have a genetic change
individual composed of cells of 2 genetically different types

113
Q

how does mosaic down’s occur

A

Occurs in nondisjunction of chromosome 21 takes place in one but NOT ALL of the initial cell divisions after fertilization
Some cells contain 46 chromosomes and others contain 47, which contain an extra chromosome 21

114
Q

How does down’s mosaicism differ from nondisjunction?

A

nondisjunction is when the the 21 chromosome is replicated in every cell division but mosaicism occurs when nondisjunction of chromosome 21 takes place in only one of the initial cell divisions instead of all.

115
Q

all males are mosaics

A

FALSE
all females

116
Q

How does x inactivation occur

A

because females are mosaics and inherit 2 Xs they have to inactivate one
the inactivated one is called a Barr Body

117
Q

lyonization

A

x inactivation

118
Q

form of germ cell mosaicism

A

x inactivation

119
Q

once an x is inactivated, will it ever reactivate?

A

NO
stays inactive throughout lifetime of the cell

120
Q

what could be an explanation of why more females are affected with autoimmune disorders?

A

some of inactivated x genes are still expressing and this only happens in women
genes create proteins that should not be there

121
Q

the paternal x is always inactivated

A

FASLE it is random

122
Q

darkened condensed chromosomal region in a cell

A

Barr body

123
Q

what is a normal female

A

random x inactivated (barr body)
active x
mix of Xm & Xp

124
Q

what is chimerism

A

presence of 2 sets of DNA or organs that do not match the DNA of the rest of the organism

125
Q

result of mosaicism

A

chimerism

126
Q

what is assortative mating

A

Mating of people with the same phenotype resulting in more expected phenotype
The Deaf community

127
Q

what is linguistic homogamy

A

Mating b/w individuals that have the same language such as “native” signers

128
Q

what is the founder effect

A

Population derived from small group or are socially isolated; common in AR
As carriers of the disease have children & the new population starts to grow, the mutated gene becomes more prevalent

129
Q

population bottleneck

A

Reduction in population size

130
Q

gene draft

A

seen in bottleneck
random fluctuations in numbers of gene variants in population

131
Q

balanced polymorphism

A

process of natural selection

132
Q

An acronym for group of diseases that cause severe fetal anomalies, HL, & death if exposed in utero

A

TORCH

133
Q

what is torch

A

toxoplasmosis
other (HIV, syphalis, etc.)
rubella
cmv
herpes

134
Q

what is a karyotype

A

all the chromosomes laid out

135
Q

disorders w/ external ear changes

A

treacher collins
BOR

136
Q

disorders w/ eye disease

A

ushers, norrie

137
Q

disorders w/ musculoskeletal

A

crouzon & stickler

138
Q

disorders w/ renal disease

A

alport

139
Q

disorders with cardiac

A

JLNS

140
Q

disorders w/ neurolgic/neuromuscular

A

friedreich ataxia

141
Q

disorders w/ endocrine

A

pendred

142
Q

disorders w/ metabolic

A

biotindase deficiency, muccopolusacharidoses (MPS)

143
Q

disorders w/ integumentary system

A

waardenburg

144
Q

disorders w/ no associated physical/mental characteristics

A

connexin & deafness

145
Q

Trisomy 13
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

patau syndrome
chromosomal disorder
brain defects, cleft palate/lip, blindness, severe intellectual disabilities, severe to profound SNHL/deafness, abnormal cochlea & vestib system

146
Q

Trisomy 18
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

Edwards syndrome
chromosomal disorder
usually female, males have high abortion
intellectual disability w/ seizures, small mouth, high arched palate, heart defects, ossification of ossicles & severe HL/deaf based on temporal bone studies

147
Q

Trisomy 21
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

down’s
chromosomal disorder: nondisjucntion, RT, mosaicism
intellectual & developmental disabilities, large tongue, stenotic ear canals, CHL, SNHL or mixed, infertility

148
Q

Turner syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

45 X0
99% fetuses abort
spontaneous mutations
short w/ thick neck, look like females, missing an x, streak gonads, infertile, narrow ear canals

149
Q

Long term consequences of ear infections?

A

S/L development

150
Q

How do babies learn language?

A

incidental learning

151
Q

Klinefelter’s syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

47 XXY
spontaneous - higher risk w/ increased maternal age
single most common cause of male infertility
man boobs at puberty, infertility, males, SNHL, tall and thin w/ long legs

152
Q

treacher collins syndrome

Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

first arch syndrome
AD
coloboma, fish like mouth, cleft palate, atresia, absent/malformed ossicles, mild-moderate bilateral CHL
OAV - unilateral vision & skeletal abnormalities

153
Q

BOR
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

second most common cause of AD HL
variable expressivity and high incomplete penetrance
renal abnormalities (polycystic kidneys), CHL SNHL or mixed that is delayed but not progressive, uni/bilateral preauricular pits or branchial fistulas, not enough urine/amniotic fluid during pregnancy
alports: usually has ocular abnormalities

154
Q

oculo-auriculo-vertebral
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

multifactorial inheritance
unilateral malformation from arches
facial asymmetry, vision loss, skeletal issues, CHL, pinna abnormalities

155
Q

what are the differences bw treacher and OAV

A

OAV is unilateral, skeletal abnormalities & visual impairments
TC has no skeletal abnormalities or visual issues & bilateral facial structures

156
Q

CHARGE association
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

coloboma
heart defects
atresia of nasal choanae
retarded growth/development
genital/urinary abnormalities
ear anomalies/deafness
behavior issues mistaken for ADHD/autism, external ear anomalies, balance issues, ossicular malformations, mondini malformation, deaf/blind

157
Q

Ushers syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

most common AR syndromic HL
progressive SNHL first & vision loss later in life from retinitis pigmentosa
most common in finnish decent
Norrie syndrome

158
Q

what are the types of ushers

A

1: more severe, abnormal vestib & congenital severe-profound SNHL
2: milder HL, no vestib
3: rare, progressive snhl w/ vestibular dysfunction

159
Q

retinitis pigmentosa

A

AR
HL SNHL
intellectual disability common

160
Q

norrie syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

x linked recessivve
male
visual problems (retinal detachment), SNHL, dementia, sunken & hazy eyes
Ushers: no CNS involvement, due to RP

161
Q

crouzon syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
early fusion of cranial bones (looks like down’s)
bulging eyes/vision problems, abnormal head shape, atresia of EAC w/ ossicular deformity, CHL but also mixed, absent or narrowed oval and/or round window

162
Q

stickler syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
Collagen disorder
eye abnormalities, mixed or progressive high frequency SNHL, joint problems

163
Q

achondroplasia
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

sporadic mutations
both parents carry dominant gene
dwarfism
average trunk w/ short arms & legs, CHL, otosclerosis, frontal bossing

164
Q

osteogenesis imperfecta
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
connective tissue disorder
blue sclera, bone fragility, CHL or mixed beginning in late teens and gradually progressing to profound deafness, tinnitus & vertigo

165
Q

alport syndrome
Mode of transmission
other systems affected
major signs/symptoms
differential diagnosis? why?

A

x linked (dom or rec)
progressive kidney inflammation to renal failure, hematuria, nephritis, bilateral variable progressive SNHL, variable eye defects
BOR: has polycystic kidneys &B.A. abnormalities

166
Q

what are the 3/4 criteria that must be met for a diagnosis of alports

A

family Hx of hematuria
renal disease from biopsy
high frequency SNHL progressive during childhood
opthalmologic signs

167
Q

Auditory neuropathy spectrum disorder ANSD
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR or mitochondrial
severe impairment of speech perception especially in noise due to disruption of synchronous VIII N firing
CI’s are treatment
only condition that audio is not used for condition determination

168
Q

what are the 3 ways ANSD is inherited

A

ar or mitochondrial
genetic nonsyndromic - abnormal OTOF gene (can be replaced in gene therapy & regain normal hearing)

genetic syndromic - associated w/ peripheral neuropathies (charcot-marie-tooth & Friedreich’s ataxia)

environmental - viral involvement (Guillen Barre syndrome)

169
Q

Charcot Marie Tooth
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
Progressive neurodegenerative disease, affects motor & sensory nerves, absent limb reflexes, muscle atrophy, slowly progressive SNHL onset in child/adulthood (could be due to auditory neuropathy)

170
Q

Friedreich’s Ataxia
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
inability to coordinate voluntary muscular movements
nystagmus, dysarthria, scoliosis, high foot arch

171
Q

what are the triad manifestations for FA diagnosis

A

hypoactive knee & ankle reflex

progressive cerebellar dysfunction

preadolescent onset

172
Q

hereditary sensory & autonomic neuropathy Type 1 (HSAN1)
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
neurodegenerative disorder
early onset dementia
lack of feeling in toes & ulceration (leading to amputation)
adult onset progressive SNHL to deafness

173
Q

neurofibromatosis (NF)
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
NF1- peripheral form, >6 cafe au lait spots, tumors on and under skin, Lisch nodules, 5% w/ VIII N tumors (vestibular schwannoma)
NF2 - central form, benign tumors, progressive vision loss, < 6 cafe au lait spots, bilateral acoustic neuromas

174
Q

management for NF2

A

ABI

175
Q

What are the parts of an ABI

A

bypassess AN & connects to the bs directly
microphone & sound processor, decoding chip under the skin, & electrodes on the B.S.

176
Q

Jervell & Lange-Nielsen Syndrome (ALNS)
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
Long AT interval, sudden death, associated w/ SIDS, bilateral severe to profound SNHL
loss of sensory cells
Ward-Romano syndrome - long QT w/ NORMAL hearing (AD)

177
Q

why do we see heart and ears affected in JLNS

A

because the K+ genes are affected and K+ is important for the ears & heart

178
Q

Pendred Syndrome
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
thyroid goiters, delayed onset, hypothyroidism, EVA, profound & rapidly progressive SNHL
DFNB4 - no thyroid defects, prelingual profound nonsyndromic SNHL, temporal bone abnormalities

179
Q

DIDMOAD
other systems affected
major signs/symptoms
differential diagnosis? why?

A

DI - diabetes insipidus (thirsty & excessive urination)
DM - diabetes millitus (thirst, excessive urination, & high blood sugar)
Optic atrophy
bilateral slowly progressing SNHL
stria vascularis atrophy in 2nd decade

180
Q

what is EVA

A

enlarged vestibular aqueduct
bony canal that begins in the temporal bone & travels from inner ear to deep in the skull
inside is a fluid filled tube (endolymphatic duct) that has the endolymphatic sac (balloon shaped structure)
MOST COMMON ANATOMIC ABNORMALITIY IN PERMANENT HL IN KIDS
unilateral/bilateral SNHL, moderate to profound, BPPV can occur

181
Q

what are the fxns of the endolymphatic duct & sac

A

help ensure homeostasis of inner ear fluid

182
Q

how to avoid progression of HL in eva kids

A

avoid contact sports that can lead to head injury
wear head protection
avoid barotrauma (rapid changes in air pressure)

183
Q

muccopolysaccharidosis
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
two types
Hurler syndrome (more severe, MPS IH) - gargoylism, course facial features, large tongue, skeletal abnormalities, large babies, developmental delays, chronic progressive, shortened lifespan

hunter syndrome (x linked, MPS II) survivable to adulthood, more common, rapid intellectual deterioration, abdominal hernia, contractures of arms, death bw 10-15 yrs

184
Q

biotidinase deficiency
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AR
deficiency of biotin
ataxia, developmental delay
optic atrophy
SNHL
affects the optic and auditory nerve and cochlea

185
Q

Waardenburg Syndrome
other systems affected
major signs/symptoms
differential diagnosis? why?

A

most common AD syndromic HL
caused by hereditary deficit of neural crest cells
white forelock hair, premature greying, vestibular abnormalities, profound w/ corner audio or moderate HL in low-mid frequencies, BM thickening
4 types

186
Q

what are the 4 types of Waardenburg Syndrome

A

WSI - more unilateral deafness, pigment disturbances, dystopia cnathorum, heterochromiairides
WS2- less unilateral HL, pigment disturbances, heterochromiairides, no dystopia canthorum
WS3 (klein-Waardenburg)- b/l upper extremity defects, hl, pigment disturbances
WS4 (Waardenburg-Shah)- rare, more severe HL (deafness), Hirschsprung disease, pigment disturbances

187
Q

what is hirschsprung disease seen in WS4

A

stool impaction/constipation
gut will not empty because the nerves to contract are missing due to the absence of neural crest ceels

188
Q

Almost all of the autosomal dominant conditions show

A

post-lingual progressive HL starting in the high frequencies

189
Q

almost all AD conditions with HL differ in

A

age of onset
rate of progression
ultimate degree of HL
vestib involvement

190
Q

AD nonsyndromic HLs

A

otosclerosis
DFNA5

191
Q

otosclerosis
other systems affected
major signs/symptoms
differential diagnosis? why?

A

ossification of the stapes footplate and its ossification into the oval window
AD
starts around the otic capsule; NO remodeling of otic capsule after embryologic development

192
Q

what is the site of lesion for otosclerosis

A

around the otic capsule

193
Q

who is the most vulnerable population for otosclerosis

A

young white females
reason unknown
menopause exacerbates this

194
Q

DFNA5
other systems affected
major signs/symptoms
differential diagnosis? why?

A

AD
progressive SNHL
HL present in childhood & progresses as they get older

195
Q

Nearly all recessive conditions are associated with

A

severe to profound SNHL that is prelingual

196
Q

> 50% of autosomal recessive nonsyndromic hearing loss is caused by

A

connexin 26

197
Q

what is connexin deafness

A

found in nonsensory epithelial & supporting cells (NOT IN COCHLEAR HAIR CELLS)
connexins associate in groups of 6
they are a hexagonal array of proteins in membrane of each cell that line up to the corresponding connexin proteins of the adjacent cell forming a channel (gap junction) that permits ion transfer bw cytoplasm of cells without entering extracellular fluid

198
Q

what are the 1st & 3rd recessive connexin deafness

A

DFNB1 & DFNB3

199
Q

what are the genes for connexin deafness

A

GJB
most common GJB2 & GJB6

200
Q

what are the protein products of GJB2 & GJB6

A

Connexin 26 (Cx26)
Connexin 30 (Cx30)

201
Q

GJB2, Cx26, is assigned to

A

13q11-q12

202
Q

how are connexins important for cellular communication

A

provide structural basis for K+ recycling back to the endolymph of the scala media after hair stimulation
responsible for intercellular calcium signaling
causes electrical coupling to support cochlear amplification

203
Q

why does Connexin not hold true of mendelians 2nd law (law of independent assortment)

A

Because GJB2 & GJB6 are so close together it is very common for them to be transmitted together

204
Q

individuals can have 2 or 1 mutation in GJB2 & GJB6. IF there are two mutations, the risk increases from

A

50-100%

205
Q

Connexin 32

A

x linked
charcot marie tooth

206
Q

connexin 26

A

protein product of GJB2 gene mutation
DFNB1/DFNB3
13q11-q12
gene mutation that results in abnormal gap junction proteins

207
Q

Responsible for 50-80% of all AR HL

A

connexin 26

208
Q

what are the common mutations of connexin 26 and the common ethnicities it affects

A

35delG - caucasians & asians
167delT - Ashkenazi jews
235delC - east asian populations

209
Q

where is connexin 26 found

A

inner ear (utricle & saccule, nonsensory epithelial), skin, liver, bladder, placenta, etc.

210
Q

what is the mutation that occurs in Cx26

A

frameshift mutation (deletion)
causes truncated proteins

211
Q

what are the auditory manifestations of Cx26

A

congenital bilateral (often symmetrical) mild to profound HL
vertigo/tinnitus reported

212
Q

other Cx phenotypes

A

skin diseases
this is why CI’s may not work for these patients

213
Q

what is the intervention for Cx

A

CI’s

214
Q

connexin 30

A

protein product of GJB6
chromosome 13?
DJB6-DFNA3

215
Q

x linked nonsyndromic HL

A

x linked congenital stapes fixation with perilymph gusher

216
Q

congenital stapes fixation with perilymph gusher
other systems affected
major signs/symptoms
differential diagnosis? why?

A

x linked
mixed HL
can be progressive if middle ear surgery is performed & can result in sudden loss of perilymph
otosclerosis

217
Q

mitochondrial nonsyndromic hl

A

aminoglycoside-induced ototoxicity

218
Q

aminoglycoside-induced ototoxicity
other systems affected
major signs/symptoms
differential diagnosis? why?

A

irreversible but preventable sudden onset severe-profound SNHL when exposed to aminoglycosides
generally not progressive
otosclerosis

219
Q

what are complex genetics? what is it mostly due to?

A

caused by environment & genes as well as the interaction bw the two
no clear inheritance pattern
due to single nucleotide polymorphisms (SNPs-snips)

220
Q

age related HL

A

complex disease
most 20 yr olds do not have HL but at least 50% of 70 yr olds do
also variety to 70 yr old that have HL (differences due to environmental factors but also genes)

221
Q

what tests would be useful for pendred symtpoms

A

physical exam - thyroid
radiology - EVA/mondini’s dysplasia

222
Q

what tests would be useful for Usher’s

A

physical exam - vestib abnormalities & visual problems

223
Q

what tests would be useful for Waardenburg

A

physical exam - hx or presence of pigment abnormalities

224
Q

what tests would be usefull for Alport

A

lab test - urine analysis & routine blood tests

225
Q

what tests would be good for BOR

A

Radiology - renal ultrasound

226
Q

what tests would be good for JLNS

A

EKG - QT interval eval
family hx of syncope or SIDS

227
Q

Lab, radiology, and other specific tests that may be useful for identification of various genetic disorders

A

factors that cause HL (low birth weight, nicu time, infections, etc.)

S/L milestones (deaf infants coo/babble up to 6 mos)

family Hx (consanguinity, family members w/ HL)

physical exam

audio exam - OAE/ABR, behavioral assessment/audio, hx of HL in family

lab tests - based on hx, physical exam & PT age

endocrine fxn

EKG

radiology

228
Q

Who should undergo genetic screening/testing?

A

children w/ HL

229
Q

If a child has a HL that is nonsyndromic, what is the first thought for a diagnosis?

A

GJB2 (Connexin 26 & 30) because they are the MOST COMMON

230
Q

Clinical benefits of identifying genetic disorders

A

provides professionals the ability to make an accurate diagnosis & prognosis
provides scientific explanation for the problem & why it occurred so it prevents the blame game
to recognize if other systems will be affected (congenital heart defects, etc.)
to recognize if there is a risk for developmental delays (intellectual disability, etc.)
provides accurate recurrence risk for offsprings

231
Q

what do they test for first? if that is negative what do they test for next?

A

Test for Connexin first, if negative, they test for EVA, +EVA = Pendred

232
Q

Ethical & psychosocial issues associated with genetic testing

A

provides info affecting reproductive choices
misassigned paternity (dad may not be biological dad)
insurance discrimination (can use test results to deny coverage to individuals)
Deaf community negative attitudes towards genetic testing (do accept it for Ushers)

233
Q

why does the deaf community accept genetic testing for Usher’s

A

because they want to be prepared for vision and HL since ASL will not be beneficial for these individuals later

234
Q

what is involved in genetic testing

A

detailed clinical & family Hx
comprehensive exam of PT & other members of family if necessary

235
Q

What are the steps to diagnose a child with HL

A

NBHS
confirmation of HL (ABR)
detailed family Hx
ENT, audiology & genetic evals
molecular testing (first GJB2&6)
if negative - cranial imaging (EVA for pendred), cardiac eval (EKG for long QT interval), ophthalmologic eval, guided molecular testing for HL genes (otoSCOPE)

236
Q

what should you do and not do in diagnosing a child with HL

A

do - detailed family hx, consider genetic etiology, rule out syndromic HL, testing for GJB genes, temporal bone imagine
do not - call sporadic/environmental, quote negligible recurrence risk, offer molecular panel for HL at outset

237
Q

what is otoSCOPE

A

otologic sequence capture of pathogenic exons
genetic panel for HL

238
Q

what is FISH

A

fluorescence in situ hybridization
provides a way to visualize and map genetic material in a cell

AUDE 5310 Embryology & Genetic Conditions (18 decks)

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