Genetics

Question 1

def: codominance

Answer 1

both alleles contribute to phenotype (blood type)

Question 2

def: variable expressivity

Answer 2

phenotype varies amoung individuals with same genotype (NF1)

Question 3

def: incomplete penetrance

Answer 3

not all individuals with mutant genotype show the mutant phenotype (BRCA1 - not everyone gets cancer)

Question 4

pleiotropy

Answer 4

one gene contributes to multiple phenotypic effects (PKU - lots of different signs/sx)

Question 5

imprinting

Answer 5

differences in gene espression depending on if the mutation is maternal or paternal (Prader-willi/angelman’s)

Question 6

anticipation

Answer 6

increased severity, or earlier onset of dx in each generation (huntington’s)

Question 7

locus heterogenetity

Answer 7

mutations at different loci can produce the same phenotype (marfan’s, MEN2B and homocysturia all cause marfanois habitus)

Question 8

heteroplasmy

Answer 8

precesnes of normal and mutated MtDNA

Question 9

hardy-weinberg shows

Answer 9

Psq +2pq + qsq. Psq is the frequency of homozygosity for allele P. Qsq is the frequency of homozygosity for allele Q. 2PQ is the frequency for hetrozygosity

Question 10

prader-willi imprinting from the

Answer 10

Paternal 15 not expressed)

Question 11

angelMan;s imprinting from the

Answer 11

Maternal 15 not expressed

Question 12

MR, hyperphagia, obesity, hypogonadiasm, hypotonia

Answer 12

Prader-Willi

Question 13

MR seziures, ataxia, inappropraite laughter

Answer 13

Angelman’s

Question 14

ragged red fibres in muscle biopsy

Answer 14

myopathy of mtDNA inheratance

Question 15

genetic defect in Achondroplasia

Answer 15

FGF receptor 3 (AD)

Question 16

genetic defect in AD polycystic kidney dx

Answer 16

PKD1 on 16 (AD)

Question 17

genetic defect in FAP

Answer 17

APC gene on 5 (AD)

Question 18

genetic defect in famial hypercholesterolemia

Answer 18

defective/absent LDL receptor (AD)

Question 19

signs of hereditary hemorrhagic telangiectasia

Answer 19

teleangiectasia, recurrent nosebleeds, skin discolorations, AVMs (AD)

Question 20

genetic defect in hereditary s[herocytosis

Answer 20

spectrin/ankyrin defect - hemolytic anemia (AD)

Question 21

treatment for hereditary s[herocytosis

Answer 21

splenectomy

Question 22

genetic defect in Huntington’s

Answer 22

CAG repetes on 4 (AD)

Question 23

tumors in MEN

Answer 23

endocrine glands (AD)

Question 24

genetic defect in NF1

Answer 24

long arm of 17 (AD)

Question 25

signs of NF1

Answer 25

cafe-au-lair spots, neural tumors, iris harmtomas (AD)

Question 26

genetic defect in NF2

Answer 26

NF2 on 22 (AD)

Question 27

sx of NF2

Answer 27

bilateral acoustic schwannomas, juvy cataracts

Question 28

tuberois sclerosis

Answer 28

facial lesions, ash-leaf spots, eye hamatromas, MR, renal cysts (AD)

Question 29

genetic defect in con hippel-Lindau

Answer 29

deletion of VHL tumor supressor on 3 (AD)

Question 30

tumors in von hippel-lindau

Answer 30

brain, retina, bilateral renal cell carcinomas

Question 31

genetic defect in CF

Answer 31

CFTR gene on 7. commonly deletion of Phe 508 (AR)

Question 32

common X linked disorders (10)

Answer 32

``` Bruton's agammt aglobulima Wiskot - aldrich fabry's G6PD defic Ocular albinism Lesch-Nyan Duchene's/Becker's MD Hunter's Hemophilia A/B Ornithine transcarbomoylase def ```

Question 33

type of mutation in Duchenne's MD

Answer 33

frameshift --> deletion of dystrophin gene (X linked)

Question 34

worst MD

Answer 34

duchenne's

Question 35

large testes, jaw and ears

Answer 35

fragile X

Question 36

genetic defect in fragile X

Answer 36

FMRI gene (X linked)

Question 37

trinucleotide expansion diseases (4)

Answer 37

Fragile X friedreich's ataxia huntington's Myotonic dystrophy

Question 38

genetic defect of down's

Answer 38

trisomy 21 mosly meiotic disjunction

Question 39

signs of down;s

Answer 39

MR, flat facies, epicanthal folds, simian cerase, duodenal atresia, endocardial cushion defect

Question 40

risks of older down's pts

Answer 40

early alzheimer's and ALL

Question 41

prenatal tests for down's

Answer 41

low a-fetoprotein high b-hcg low estroil high inhibin A

Question 42

edwards's syndrome

Answer 42

severe MR, rocker bottom feet, small jaw, low-se ears, congenital Heart dx

Question 43

genetic defect in edwards's disease

Answer 43

trisomy 18

Question 44

genetic defect in patau's syndrome

Answer 44

trisomy 13

Question 45

patau's syndrome

Answer 45

severe MR, small jaw/ears, cleft lip/palate, holoprocephaly, polydactly, congenitcl heart dx

Question 46

genetic defect in cr- du chat

Answer 46

microdeletion of chromosome 5 short arm

Question 47

slight MR, high functioning verbal skills, extreme friendliness, CV problems

Answer 47

williams syndrome

Question 48

digeorge syndrome genetic defect

Answer 48

microdeletion at 22q11

Question 49

disdevelopment in digeorge

Answer 49

3rd and 4th branchial pouches