cytogenetics

Question 1

light bands on chromosomes

Answer 1

GC rich - gene rich

Question 2

Nondisjunction at M1 leads to

Answer 2

n+1, n+1, n-1, n-1

Question 3

Nondisjunction at M2 leads to

Answer 3

n, n, n+1, n-1

Question 4

klinefelters and type of nondisjunction

Answer 4

47 XXY
Either M1 - nondisjunction of paternal gamete (Xy)
Or M2 - nondisjunction of sister chromatids maternal gamete

Question 5

webbed neck

aortic defect

Answer 5

Turner

Question 6

Hypogonadism, infertile, tall thin

Answer 6

Klinefelter

Question 7

Which syndrome is the most rare?

Answer 7

Turners

- high incidence of abortion, >99% miscarriage

Question 8

Classic signs trisomy 18

Answer 8

• 1/7500 births
• failure to thrive
• severe heart malformation
• clenched fists, overlapping digits
• rocker-bottom feet

Question 9

Classic signs trisomy 13

Answer 9

• CNS malformation
• arhinencephaly, holoprosenceph
• polydactyly
• micropthalmia
• low chance survival of prenatal period

Question 10

Triploidy is

Answer 10

non viable

not due to maternal age

Question 11

Which trimester Amnio vs CVS?

Answer 11

1- second trimester for amnio, vs 1st trimester

Question 12

Mosaicism if detected prenatally

Answer 12

May or MAY NOT reflect fetal karyotype

- can be from placental cells or amniotic sac not fetus

Question 13

Somatic mosaicism often associated

Answer 13

with malignancy

Question 14

Cri du chat syndrome is a

Answer 14

Chr 5 p deletion
cat like cry
facial dysmophism

Question 15

in reciprocal translocations the carrier is often

Answer 15

Normal

Question 16

Deletions or duplications less than? cannot be detected by G band karyotype

Answer 16

< 5-10 Mbp

Question 17

Di george syndrome is

Answer 17

a microdeletion 22q11.2 - 3Mb deletion

Question 18

Which carries a more severe phenotype? Microdeletion or microduplications?

Answer 18

Microdeletions