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Med foundations 1 Flashcards

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1
Q

Constitutional/Congenital

A

Present at birth

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2
Q

Pathogenetic (definition)

A

Genetic alteration causing disease

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3
Q

Obligate Carrier (define)

A

Parent of a child with a recessive condition

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4
Q

Mosaic (define)

A

Two or more cell lines in one person

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5
Q

Chimera (define)

A

Mix of two cell lines, think of bone marrow transplant

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6
Q

Consanguinity

A

Individuals descended from common ancestor; second cousin or closer. .2% of US

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7
Q

Acquired

A

somatic change after birth, usually cancer related

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8
Q

SAB

A

spontaneous abortion

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9
Q

FTT

A

failure to thrive-doesnt put on weight

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10
Q

Two examples of autosomal dominant inheritance

A

Achondroplasia–GOT midget

Marfan’s Disease

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11
Q

Variable Expressivity (define) and give an example.

A

features of a disorder vary between individuals even in the same family. Usually autosomal dominant disorders have variable expressivity. Example: marfan syndrome

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12
Q

Marfan Syndrome

A

Tall lanky, disorder of connective tissue. Mortality: dilation of the aorta resulting in rupture.

Exhibits variable expressivity: people in same family may have to different degrees

also an example of dysplasia (defect in fibrilin)

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13
Q

Incomplete Penetrance (definition and example)

A

Not all individuals with a mutation have phenotypic effects. Ex: BRCA gene mutation

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14
Q

Explain the difference between variable penetrance, variable expressivity, and having both.

A

EX: BRCA gene. Only some people w/ gene get disorder (variable penetrance). And people who have the gene have different types of cancer (variable expressivity).

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15
Q

De novo mutation

A

New mutations can occur at “hot spots”.
Rate of new mutations increases with advancing paternal age.
Ex:: 80% of achondroplasia cases are de novo.

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16
Q

Examples of recessive inheritance

A

Cystic fibrosis

Sickle Cell

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17
Q

How is cystic fibrosis inherited?

A

recessively.

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18
Q

Is penetrance in autosomal recessive diseases complete or incomplete?

A

usually complete. if you have two copies, you have the disease.

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19
Q

Examples of recessive autosomal inheritance with ethnic correlations

A

Sickle Cell

Tay Sachs

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20
Q

Example of X-linked recessive inheritance and details of disease

A

Hemophilia: bleeding caused by factor 8 deficiency, life expectancy reduction by about 10 yrs.

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21
Q

Characteristics of X-linked diseases

A

Male to male transmission not observed. Males more likely than females to be affected. All daughters of an affected male are carriers. Female carriers may show milder version of trait

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22
Q

Lyonization (X-inactivation)

A

Explains why some female carriers of an x linked disorder might show some characteristics. One x chromosone is turned off in cells. A skewed ratio could lead to a phenotype. An example would be women exhibiting less severe symptoms of duchenne muscular dystrophy.

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23
Q

Duchenne Muscular Dystropy

A

X-linked recessive inheritance. skeletal muscle disease. life expectancy around 27 yrs

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24
Q

When could a female be affected by a recessive X linked disorder?

A
  • Turners syndrome
  • skewed x-inactivation
  • she has an affected father and carrier mother
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25
X-linked dominant inheritance (example)
Incontinentia Pigmenti; disorder of skin hair teeth etc. cognitive delays
26
X-linked dominant inheritance mechanism
Females are much more likely than males to be affected. male to male transmission not observed
27
How many genes on mitochondria?
37
28
MELAS
Mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes; hearing loss, diabetes, seizures, intellectual disability
29
Heteroplasmy and Homoplasmy
mix of normal and abnormal mtDNA vs. all mt DNA is the same
30
Threshold effect in mtDNA
Threshold for symptoms showing
31
How does mitochondrial function vary with age?
Mt function decreases with age.
32
Anticipation (definition)
Increase in severity of phenotype in successive generations. Related to trinucleotide repeats
33
Example of disease with anticipation
Myotonic Dystrophy has a spectrum of severity depending on repeats. affects skeletal and smooth muscle; myotonia--sustained muscle contraction. Fragile X syndrome most common inherited cause of intellectual diability. Severity doesnt increase with repeats, but likelihood of having it does
34
Fragile X syndrome characteristics of carriers
female carriers have increased risk of early menopause males are at risk for parkinsons syndrome
35
Mosaic Down syndrome
less severely affected. 1-2% of down syndrome.
36
Pallister Killian Syndrome
Mosaic tetrasomy 12p. low muscle tone, characteristic facies, hypopigmentation Only seen in mosaic form because the non mosaic form is lethal.
37
When should gonadal mosaicism be inferred?
When two offspring have an autosomal dominant disorder with no other family history.
38
Why are digynic triploidy and diandric triploidy evidence for imprinting?
Because depending on whether you get two copies from mom (digynic) or dad you get a different result.
39
Russell Silver Syndrome
small features, triangle face. about 10% of cases occur with uniparental disomy on chromosone 7.
40
Prader-Willi Syndrome
Hyperphagia; intellectual disability. "Prader no fader"
41
Angelman Syndrome
Severe disability. Caused by lack of genes on the maternal allele
42
Major anomalies vs. Minor anomalies
medical surgical intervention needed, cosmetically important. Minor: no major surgery
43
22q11 deletion syndrome
Piece of long arm of 22nd chromosone missing. 74% of kids have a heart defect. palette anomalies, nasal voice. Looks phenotypically different, have to look at patients carefully.
44
Malformation (definition+ex)
Defect from an intrinsically abnormal deveopment process; occurs at 8-10 weeks. ex: heart defect, cleft lip,
45
Deformation (definition +ex)
abnormality from mechanical forces; occurs AFTER 8-10 weeks, ex: clubbed foot, overlapping toes. Squished against side of placenta.
46
Disruption (definition+ex)
environmental disturbance, think of tunnel being completely blocked wheras in deformation tunnel is only partially blocked. Ex: oligodactyly--amniotic band compression. cleft palate
47
Dysplasia
Abnormal organization of cells into tissues. Ex: polycystic kidney disease. dented chest
48
Syndrome (definition and example)
multiple anomalies thought to be pathogenically related
49
Sequence (definition and example)
cascade from single known anomaly or MECHANICAL factor. Ex: Pierre robin sequence. micrognathia-->glossoptosis-->cleft palette Potter sequence : lack of fetal urine-->anhydamnios--> fetal compression-->hypoplasia
50
Field Defect (definition and example)
derived from the disturbance of a single developmental field. Ex: a midline development issue Ex: OEIS (external bowels) or holoprosencephaly spectrum
51
Association (definition and example)
Non random occurrence of multiple anomalies that cannot be explained by chance. UNKOWN factor. Ex: VATERAL (Vertebral anomalies, anus, cardiac, TEF, renal, limb
52
Teratogen (definition)
exposure in pregnancy with a harmful effect ex: infection, medications, drugs, heavy metals, procedures
53
Characteristics of teratogens
dose response relationship period of greatest sensitivity
54
Examples of teratogens
thalidomide warfarin (coumadin) acutane
55
Where are men placed on a pedigree?
to the left of females
56
Three principles of mendellian inheritance
1. unit inheritance 2. segregation 3. independant assortment
57
What organ systems are most likely to be affected in mitochondrial disorders?
Systems w. large ATP requirements. CNS, skeletal muscle, eye muscle, heart muscle (muscles +brain)
58
Heterodisomy vs. isodisomy
in heterodisomy, the parent provides one copy of each homologous chromosone. In isodisomy, the parent passes on two IDENTICAL copies of hte same chromosone
59
dysmorphic features
variants of physical features that are present in less than 2-3% of population
60
What percent chance is there that a person has a syndrome if they have.... 1 anomaly? 2 anomaly? 3 anomaly?
1 anomaly: 3% chance 2 anomalies: 10% chance 3 anomalies: 20% chance
61
More examples of teratogens
ace inhibitors, androgens, cocaine, vitamin A, some antibiotics
62
Hardy Weinberg and what p and q stand for
p^2+2pq+q^2=1 q^2 is incidence of homozygotes=incidence of AR disease 2pq=heterozygotes=incidence of carriers
63
How would you calculate if "at least 1" child will have a disease?
At least 1= 1-none
64
Multifactorial genetics (definition)
combined contribution of genes and environmental factors in the causation of a particular disease or trait
65
What are the two types of multifactorial traits?
quantitative and threshold
66
What is liability in multifactorial inheritance?
liability is the total combined genetic and environmental factors that influence the development of a multifactorial disorder or trait
67
can liability be measured?
no
68
Examples of liability differences between males and females
cleft lip and palate: M>F congenital hip dysplasia F>M Pyloric stenosis: M>F
69
Recurrence risk rules
Recurrence risk is greater if.... 1. greater severity 2. more than one family member is affected 3. more closely related family members 4. if proband is of less commonly affected sex 5. recurrence risk of 1st d relative is equal to square root of population incidence
70
heritability (definition)
How much of a phenotypic variance is caused by genes vs environment?
71
Genetic risk factors of AD
Apolipoprotein E (APOE) : if you have a copy of the e4 allele, your risk increases 2-5x; if you have 2 copies your risk increases 5-10x
72
What is recurrence risk rate for birth defects?
4%
73
polygenic trait
results from the combined influence of multiple genes
74
Signs of multifactorial inheritance
familial concentration absence of clear biochemical defects from 1 gene variation in severity and expression gender differences
75
What percent of breast cancer is due to an inherited change? (BRCA, p53, etc)
about 5-10%
76
If you see a pedigree with only affected women, what is the mode of inheritance?
X linked dominant
77
What percent of children are diagnosed with a birth defect at birth? after 1 year?
3%, 4%
78
Concurrence of minor and major anomalies
If a child has 3 or more minor anomalies, 20-90% more likely to have a major malformation

Genetics (2 decks)

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