Genetics Flashcards

1
Q

Gene that encodes ATP-gated chloride channel that secretes Cl- in the lung, GI tract and sweat glands
mutation is misfolded protein that is retained in the RER
AR

A
CFTR
Phe508 deletion
Cl- > 60 mEq/L in sweat is diagnostic
Newborn: meconium ileus
deficiency: ADEK vitamins (pancreatic insuff)
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2
Q

truncated dystrophin protein
X-linked frameshift mutation
accelerated muscle breakdown with pelvic girdle weakness and superior progression
Pseudohypertrophy of calf muscle from fibrofatty replacement
Gower maneuver to aid standing
Cause of death: dilated cardiomyopathy

A
Duchenne muscular dystrophy
Gene: DMD
dystrophin connects actin to ECM
Lab: Increased CPK & aldolase
Dx: bx and Western blot
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3
Q

point mutation in dystrophin

onset in adolescence or early adulthood

A

Becker muscular dystrophy

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4
Q

muscle wasting, frontal balding, cataracts, testicular atrophy, arrhythmia
CTG repeat expansion of DMPK gene

A

myotonic dystrophy (type 1)

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5
Q

CGG trinucleotide repeat
altered expression of FMR1 gene due to methylation
X-linked defect
Genetic mental retardation
Post-pubertal enlarged testes, long face with large jaw, large everted ears, autism, mitral valve prolapse

A

Fragile X syndrome

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6
Q

Brushfield spots
ASD
intellectual disability, flat facies, prominent epicanthal fold, single palmar crease, gap between 1st and 2nd toes, duodenal atresia, increased risk of ALL, AML and Alzheimer disease
meiotic nondisjunction -> advanced maternal age

A

Trisomy 21

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7
Q
severe intellectual disability
rocker bottom feet
micrognathia
low-set ears, prominent occiput
clenched hands
congenital heart disease
death within 1 year
A

Trisomy 18 = Edwards syndrome
Lab: decreased PAPP-A, free beta-hCG in trimester
Quad screen: decreased AFP, beta-hCG, estriol, decreased normal inhibin A

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8
Q
severe intellectual disability
rocker bottom feet
microphthalmia
microcephaly
cleft lip/palate
holoprosencephaly
polydactyly
congenital heart disease
A

Patau syndrome = trisomy 13
1st trimester screen: decreased free beta-hCG, PAPP-A,
increased nuchal translucency

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9
Q

occurs when long arms of 2 acrocentric chromosomes fuse at the centromere with loss of the 2 short arms

A

Robertsonian translocation
balanced = no problem
unbalance = miscarriage, stillbirth, chromosome imbalance

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10
Q

congenital microdeletion of short arm of chromosome 5
microcephaly
moderate to severe intellectual disability
high-pitched cry
epicanthal folds
VSD

A

Cri-du-chat syndrome

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11
Q

congenital deletion of long arm of chromosome 7 (includes elastin gene)
elfin facies, intellectual disability,
hypercalcemia** (increased sensitivity to Vit D)
extreme friendliness to strangers
cardiovascular problems

A

Williams syndrome

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12
Q

22q11 deletion syndromes

A

DiGeorge syndrome

Velocardiofacial syndrome

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13
Q

one gene contributes to multiple phenotypic effects

A

pleiotropy

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14
Q

tumor suppressor gene mutation that is expressed when complementary allele is deleted/mutated

A

loss of heterozygosity

This does not happen with oncogenes

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15
Q

nonfunctional altered protein prevents normal gene product from functioning

A

dominant negative mutation

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16
Q

both alleles contribute to the phenotype of the heterozygote

A

codominance

ex: blood groups; alpha1-antitrypsin deficiency

17
Q

not all individual with a mutant genotype show the mutant phenotype

A

incomplete penetrance

18
Q

mutations at different loci can produce a similar phenotype

A

locus heterogeneity

ex: albinism

19
Q

different mutations at the same locus can produce a similar phenotype

A

allelic heterogeneity

ex: beta-thalassemia

20
Q

presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease

A

heteroplasmy

21
Q

methylation of one allele makes it inactive

deletion of the active allele produces disease

A

imprinting

22
Q

gene from dad is silent (imprinting); maternal gene deleted/mutated
inappropriate laughter, seizures, ataxia, severe intellectual disability
“happy puppet”

A

Angelman syndrome
Paternal imprinting
“Angel’s daddy is silent in church but laughs at inappropriate jokes”

23
Q

gene from mom is silent; paternal gene is mutated/deleted
hyperphagia, obesity, intellectual disability,
hypogonadism, hypotonia

A

Prader-Willi
Maternal imprinting
“willi’s mama is silent when she’s overeating”

24
Q

mnemonic for blotting procedures

A

SNoW DRP
Southern blot = DNA
Northern blot = RNA
Western blot = protein ex: HIV

25
blotting technique to identify DNA-binding proteins
Southwestern blot
26
often present with myopathy, lactic acidosis, & CNS disease secondary to failure in oxidative phosphorylation muscle bx: ragged red fibers
mitochondrial myopathies
27
AD | mutation in PKD1
polycystic kidney disease
28
AD | mutations of APC gene on chromosome 5
FAP | familial adenomatous polyposis
29
AD | mutation in fibrillin-1 gene
Marfan | CT disorder, pectus excavatum, aortic incompetence -> aneurysms, floppy mitral valve, subluxation of lenses
30
AD | mutation in NF1 gene on chromosome 17
neurofibromatosis type 1
31
AD bilateral acoustic schwannomas, juvenile cataracts mutation on chromosome 22 NF2
neurofibromatosis type 2
32
AD numerous benign hamartomas incomplete penetrance & variable expression
tuberous sclerosis
33
deletion of VHL gene on chromosome 3 | development of multiple tumors
von Hippel-Lindau disease
34
AD mutations of RET familial tumors of endocrine glands
MEN2A & 2B