Medical genetics

Question 1

What is a deformation?

Answer 1

an External factor causes an anomaly

Question 2

What is a disruption?

Answer 2

a developmental process is Interrupted

Question 3

What is a malformation?

Answer 3

wrong directions- genetic cause

Question 4

What VACTERL stand for?

Answer 4

vertebral
anorectal
cardiac
tracheoesophageal atresia or fistula
ear
renal
limb

Question 5

What is the yield for CMA for delays/ID? ASD?

Answer 5

delays/ID ~13%
ASD ~8%

Question 6

What is the yield for WES for delays/ID? ASD?

Answer 6

delays/ID ~30%
ASD ~16%

Question 7

What percent of autism cases are caused by Fragile X?

Answer 7

5%

Question 8

What percent of autism cases are caused by PTEN?

Answer 8

1%
5% of autism +macrocephaly

Question 9

What is the recurrence risk for autism if the cause is unknown?

Answer 9

10-15%

Question 10

What is the recurrent risk for autism if two children are affected?

Answer 10

50% recurrence for boy
12% for girl

Question 11

What percent of T21 cases have hearts defects?

Answer 11

50%

40% AVSD
32% VSD
10% ASD
6% TOF

Question 12

What is the breakdown of causes of T21?

Answer 12

95% NDJ
-90% maternal
–77% MI
–23% MII
-10% paternal
4% Robertsonian
1% mosaic
<1% partial duplications

Question 13

What is the recurrence of T21 caused by Robertsonian translocations?

Answer 13

10-15% if maternal
<5% if paternal

Question 14

What percent of amenorrhea is due to Mayer-Rokitansky-Kuster-Hauser?

Answer 14

15%

Question 15

What are causes of macrosomia?

Answer 15

diabetic mother
overgrowth disorders: BWS, Sotos, PTEN, Weaver

Question 16

What proportion of hearing loss has a syndromic cause?

Answer 16

1/3

Question 17

What invalidates galactosemia screening on the NBS?

Answer 17

blood transfusion

Question 18

What percent of NBS are positive and what percent of those are false positives?

Answer 18

1% positive
90% positives are false positives
(PPV 10%)

Question 19

How is penetrance calculated?

Answer 19

individuals with phenotype / individuals with genotype

Question 20

When are epigentic factors determined?

Answer 20

during gametogenesis before fertilization

Question 21

What organ removes RBC?

Answer 21

the spleen

Question 22

Which organ recycles iron?

Answer 22

the liveer

Question 23

What is a reticulocyte?

Answer 23

immature RBC

Question 24

When in gestational development does the neural tube form?

Answer 24

3-4 weeks GA

Question 25

What percent of fetuses with holoprosoencephaly have a chromosomal abnormality?

Answer 25

33%
T13

Question 26

Which sex is affected more frequently by Dandy Walker malformations?

Answer 26

female

Question 27

Where are B cells made? T cells?

Answer 27

B cells -Bone marrow
T cells -Thymus

Question 28

What is the breakdown of causes of POI?

Answer 28

75% non- genetic
25% genetics: 12% single gene including FMR1, 13% chromosomal

Question 29

What does hemoglobin makes when it breaks down?

Answer 29

bilirubin

Question 30

What are the subunits of:
HbA
HbF
HbA2
?

Answer 30

HbA: two alpha two beta
HbF: two alpha two gamma
HbA2: two alpha two delta

Question 31

What percent of fetuses afffected by holoprosencephaly have a chromosome abnnormality?

Answer 31

33%
Trisomy 13 most common

Question 32

What signs are seen on imaging with agenesis of the corpus callosum?

Answer 32

Texas longhorn sign
associated with an interhemisepheric cyst

Question 33

What percent of individuals with agenesis of the corpus callosum have normal development?

Answer 33

76%

Question 34

What sex is more commonly affected with Dandy Walker malformation?

Answer 34

females > males

Question 35

What percent of POI has a genetics cause?

Answer 35

25%
12% single gene (includes FMR1)
13% chromosomal

Question 36

What percent of Alzheimer’s is early onset (<60-65), and what percent is familial?

Answer 36

5% early onset
25% familial