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Genetics Flashcards

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1
Q

Locus

A

the specific location of a gene on a chromosome

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2
Q

Alleles

A

different versions of a gene, humans have 2 alleles for each autosomal gene

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3
Q

What is a gene?

A

hereditary units of DNA transmitted from one generation to another, code for proteins

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4
Q

What are homologous chromosomes?

A

chromosomes that have the same genes at the same loci; one maternal and one paternal

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5
Q

genome

A

genetic information, haploid set of chromosomes for a particular species

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6
Q

somatic cells

A

contain one set of chromosome from female parent and one homologous set from male parent

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7
Q

Haploid number?

A

n, the number of chromosomes in sex cells (n=23)

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8
Q

diploid number

A

2n, the total number of chromosomes in somatic cells (2n=46)

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9
Q

Name the 3 components of a chromosome

A

short arm (p)

centromere

long arm (q)

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10
Q

What are chromosomes except sex chromosomes called?

A

autosomes

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11
Q

What is a karyotype?

A

a pictures of a person’s chromosomes

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12
Q

mitosis

A

the process by which all somatic cells become descendants of one original cell. Original cell is divided into 2 daughter cells, producing exact copies

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13
Q

meiosis

A

process by which gametes cells are produced (egg and sperm)

2 consecutive cell divisions producing cells with half the original chromosome number

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14
Q

spermatogenesis

A

diploid primordial cells in testes become spermatogonia

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15
Q

oogenesis

A

diploid primordial ovaries become oogonia

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16
Q

What is codominance?

A

when 2 alleles for a trait are equally expressed (ex. AB blood type)

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17
Q

What is incomplete dominance?

A

heterozygotes have phenotypes that have both alleles visible as a blend (ex. wavy hair)

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18
Q

Penetrance

A

the probability that individuals in a population who have a particular gene combination will show the condition

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19
Q

Genetic marker

A

Sequence of DNA with a known location on a chromosome

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20
Q

Expression

A

the components of the phenotype that are exhibited in an individual (2 people with the same gene may express it differently)

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21
Q

Anticipation

A

genetic disease that increase in severity or have earlier onset with each generation (ex. Huntington)

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22
Q

What are balanced chromosomal abnormalities? Name the two types of balanced abnormalities

A

no net loss or gain of chromosomal material

Balanced translocation- ruptured chromosome, re-sticking in wrong combination

inversion- piece of chromosome flipped around and reinserted

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23
Q

Name the types of unbalanced chromosomal abnormalities

A

deletions
insertions
unbalanced translocation

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24
Q

Functions of 3 generation pedigree

A

Helps with:

  • making a dx
  • deciding on testing
  • establishing pattern of inheritance
  • identifying people at risk
  • educating pt
  • determining reproductive options
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25
Describe the characteristics of autosomal dominant transmission
vertical pattern of transmission multiple generations affected variable expressivity reduced penetrance M/F equally affected
26
Autosomal Recessive
2 copies of diseased allele required for expressing the phenotype rare males and females equally affected often occurs in the context of consanguinity
27
Describe the characteristics of autosomal recessive transmission
horizontal pattern single generation affected M/F equally higher association with consanguinity
28
x-linked
no male to male transmission males are usually more severely affected than females "x-linked recessive" and "x-linked dominant" only apply to females
29
Multifactoral/complex disease
caused by interactions of variations in multiple genes and environmental factors These genes make a person susceptible to a disorder and certain environmental factors trigger the susceptibility
30
Down syndrome
trisomy 21 most common chromosomal abnormality in live birth increased incidence with advancing maternal age
31
What kind a testing can an expecting mother have to evaluate for down syndrome?
quad screening nuchal translucency
32
What are the characteristics of down syndrome?
intellectual disability, characteristic facial appearance, increased social skills in childhood some may have: cardiac defects, hearing loss, visual problems, GI defects, alzheimer disease in adulthood
33
trisomy 18
Edwards syndrome many die before birth or in first month inter uterine growth restriction. 2% 1 yr survival rate increased risk with advanced maternal age
34
characteristics of trisomy 18
kidney and heart defects, developmental delay, club foot, low set ears, small jaw
35
trisomy 13
Patau syndrome increased risk with advanced maternal age
36
characteristics of trisomy 13
severe intellectual disability, many physical abnormalities, cleft lip or palate, seizures, small jaw, polydactyly, heart defects, brain/spinal cord abnormalities many children die within first days or weeks or life
37
Cri-du chat syndrome
deletion of part of short arm of chromosome 5 partial monosomy can be detected in utero with chorionic vila sampling
38
define partial monosomy
when only a portion of a chromosome has one copy instead of two
39
characteristics of cri-du-chat syndrome
cat like cry of affected children due to abnormal larynx development, intellectual disability, wide set eyes, low ears
40
kleinflelter's syndrome
Extra X chromosome, XXY occurs during gametogenesis affects male physical and cognitive development accounts for many first trimester loses
41
characteristics of Klinefelter's syndrome
physical traits become more apparent after puberty hypogonadism, infertility, gynecomastia (breasts in man), reduced hair
42
turner syndrome
45 X, affects development in females monosomy
43
characteristics of turner syndrome
non-functional ovaries, short stature, broad chest, webbed neck, amenorrhea, infertility, cardiovascular abnormalities
44
huntington's disease
A neurodegenerative disease- progressive brain disorder that directly effects the nerves of the brain autosomal dominant-only human disorder of complete dominance adult onset: genetic defect is latent for 3-5 decades then manifests as progressive neuronal dysfunction
45
characteristics of huntington's disease
causes uncontrolled movements, emotional problems, loss of thinking ability, changes in personality early signs: depression, irritability, poor coordination, trouble learning
46
involuntary jerking movements associated with huntington's disease?
chorea
47
Which chromosome is the huntington's disease gene located? What does it code for?
chromosome 4 codes for a unique protein called huntingtin: CAG trinucleotide repeat abnormal protein causes microscopic deposits of protein in neurons
48
Alzheimer's disease
neurodegenerative disease, most common form of dementia in elderly
49
familial alzheimer's disease
aka early onset AD symptoms onset before 65 mutations on chromosomes 1, 14, or 21 rare, autosomal dominant
50
sporadic alzheimer's disease
aka late onset AD more common form gene shown to increase risk: chromosome 19 apolipoprotein definitive dx: autopsy-plaques and tangles
51
What are the 2 major breast cancer susceptible genes?
BRCA1 on chromosome 17 and BRCA2on chromosome 13 (tumor suppressor genes)
52
colorectal cancer
results from the interaction of both genetic and environmental factors
53
Familial adenomatous polyposis
<1% of all colorectal cancers mutation in APC gene cancer develops in 20s recommended: total colectomy
54
Hereditary Nonpolyposis colorectal cancer (HNPCC)
aka lynch syndrome autosomal dominant inheritance mutation in one of the many genes that code for DNA repair cancers occur in 30s and 40s
55
chronic myelogenous leukemia
myeloproliferative disorder more common in men genetic defect: translocation between chromosomes 9 and 22 Philadelphia chromosome (22): produces a protein that codes for an enzyme that causes too many stem cells to develop into WBCs
56
clinical presentation of chronic myelogenous leukemia
insidious onset, slow progression over months to years of infections, anemia, bleeding, fever, night sweats, fatigue
57
Hemophilia
bleeding disorders caused by mutations in genes that code for coagulation proteins
58
What mutation causes hemophilia?
mutation on F8 or F9 genes, located on the X chromosome
59
What is the pattern of inheritance for hemophilia?
X-linked recessive pattern
60
What are the clinical manifestations of hemophilia?
hemarthroses, bleeding into muscles and other soft tissues; prolonged bleeding or oozing of blood after injury or surgery
61
sickle cell disease
atypical hemoglobin molecules (hemoglobin S), crescent shape
62
clinical manifestations of sickle cell disease
anemia, infections, episodic pain, SOB, fatigue, delayed growth
63
mode of inheritance of sickle cell disease
autosomal recessive
64
cystic fibrosis genetic mutation
mutation in the CFTR gene(cystic fibrosis transmembrane conductance regulator)
65
mode of inheritance for cystic fibrosis
autosomal recessive
66
clinical manifestations for cystic fibrosis
thick, sticky mucous obstructing airways in lungs and ducts in pancreas meconium ileus- newborn intestinal obstruction due to thick fecal waste products
67
What is the most common cause of morbidity associated with CF?
pulmonary disease
68
what is the primary test for cystic fibrosis dx?
sweat chloride test, defective chloride channel doesn't allow chloride to be reabsorbed
69
marfan syndrome mode of inheritance?
autosomal dominant
70
mutation responsible for marfan syndrome
inherited mutation or a new mutation of the fibrillin-1 gene (FBN1) codes for connective tissue proteins
71
clinical manifestations of marfan syndrome
tall stature, long thin arms and legs, arm span wider than body height, scoliosis, hyperflexible joints, overcrowded teeth dislocated lens of the eye, AA/dissection
72
Neurofibromatosis Type I
aka recklinghausen disease autosomal dominant mutation on NF1 gene on chromosome 17 (tumor supressor gene)
73
manifestations of neurofibromatosis Type I
growth of neurofibromas-benign tumors that grow on nerves of skin and brain, changes in skin pigmentation (cafe au lait spots)
74
What is the crowe sign seen in neurofibromatosis Type I?
axillary or inguinal freckles
75
Polycystic Kidney disease
clusters of fluid filled sacs in kidneys, affects ability to filter the blood properly, they can become enlarged and fail
76
clinical manifestations of polycystic kidney disease
HTN, back pain, hematuria, UTIs, kidney stones
77
What are the two types of polycystic kidney disease?
autosomal dominant- sxs in adults autosomal recessive-rare, lethal
78
What is done during a newborn screening?
biochemical analysis that determines whether certain proteins are present or absent, checks for metabolic disorders
79
when are the 2 tests for newborn screening performed?
1st: heel stick at 24-36 hrs 2nd: first office visit between 5-10days

Foundations (6 decks)

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