Genetics Flashcards Preview

Step 1 > Genetics > Flashcards

Flashcards in Genetics Deck (34):
1

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

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

2

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

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

3

point mutation in dystrophin
onset in adolescence or early adulthood

Becker muscular dystrophy

4

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

myotonic dystrophy (type 1)

5

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

Fragile X syndrome

6

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

Trisomy 21

7

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

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

8

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

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

9

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

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

10

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

Cri-du-chat syndrome

11

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

Williams syndrome

12

22q11 deletion syndromes

DiGeorge syndrome
Velocardiofacial syndrome

13

one gene contributes to multiple phenotypic effects

pleiotropy

14

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

loss of heterozygosity
This does not happen with oncogenes

15

nonfunctional altered protein prevents normal gene product from functioning

dominant negative mutation

16

both alleles contribute to the phenotype of the heterozygote

codominance
ex: blood groups; alpha1-antitrypsin deficiency

17

not all individual with a mutant genotype show the mutant phenotype

incomplete penetrance

18

mutations at different loci can produce a similar phenotype

locus heterogeneity
ex: albinism

19

different mutations at the same locus can produce a similar phenotype

allelic heterogeneity
ex: beta-thalassemia

20

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

heteroplasmy

21

methylation of one allele makes it inactive
deletion of the active allele produces disease

imprinting

22

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

Angelman syndrome
Paternal imprinting
"Angel's daddy is silent in church but laughs at inappropriate jokes"

23

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

Prader-Willi
Maternal imprinting
"willi's mama is silent when she's overeating"

24

mnemonic for blotting procedures

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