Genetics

Question 1

most common cause of aneuploidy

Answer 1

nondisjunction

Question 2

most common genetic cause of moderate mental retardation

Answer 2

trisomy 21

Question 3

maternal screening for down syndrome at 2nd trimester

Answer 3

free B HCG
unconjugated estriol
inhibin
alpha fetoprotein

Question 4

in down syndrome, most common source of supernumerary chromosome 21 is

Answer 4

maternal origin

Question 5

majority of translocations in down syndrome

Answer 5

robertsonian translocations

Question 6

in robertsonian translocations, chromosomes with fusions at centromere ar

Answer 6

13
14
15
21
22

Question 7

gonads are streaks of fibrous tissue

Answer 7

gonadal dysgenesis

Question 8

t or f

maternal age is a predisposing factor for turner

Answer 8

false

Question 9

each additional X in klinefelter lowers IQ by

Answer 9

10-15 points

Question 10

t or f

puberty in klinefelter is delayed

Answer 10

false

Question 11

mental retardation
autistic
macro orchidism
long face, large ears, square jaw

Answer 11

fragile x

Question 12

rules in autosomal dominant inheritance

Answer 12

1. trait appears in every generation
2. each child has 1 in 2 chance
3. male = females affected
4. male to male transmission
5. genes that code for regulatory/structural proteins

Question 13

rules in autosomal recessive inheritance

Answer 13

1. trait appears in siblings, not in parents/offspring
2. normal sibling has 2/3 chance of being a carrier
3. male = females affected
4. consanguinity
5. genes that code for enzymes

Question 14

rules in x linked recessive inheritance

Answer 14

1. trait higher in males
2. female carriers
3. each son of carrier female 1 in 2 chance
4. affected father passes to all daughters, never transmitted to son
5. skip generations