Cytogenetics II

Question 1

Trisomy 21 features

Answer 1

MR, epicanthal folds, upward slanting palpebral fissures, abundant neck skin, umbilical hernia, fifth finger clinodactyly, simian crease, gap between first and second toe, CHDs

Question 2

Trisomy 21 digressions

Answer 2

maternal age and normal parent carrying a Robertsonian translocation

Question 3

dictyotene

Answer 3

prolonged phase in the female meiosis between synapsis/recombination in the two meiotic cell divisions

Question 4

Trisomy 13 (Patau Syndrome) features

Answer 4

small eyes, polydactyly, microcephaly, cleft lip and palate, CHD, umbilical hernia, renal defects, Rocker-bottom feet

Question 5

trisomy 13 polydactyly

Answer 5

usually post-axially (pinky region)

Question 6

Trisomy 18 (Edwards Syndrome) features

Answer 6

low set weirdly rotated ears, CHD, overlapping fingers, prominent occiput, horseshoe kidney, Rocker-bottom feet, small chin

Question 7

Cri du chat syndrome

Answer 7

deletion in 5p; mewing-cat like cry, microcephaly, hypertelorism, MR

Question 8

DiGeorge syndrome

Answer 8

deletion in 22; small chin, cylindrical nose, seizures, hypoplasia of thymus (T cell deficit), cardiac defects

Question 9

Williams syndrome

Answer 9

deletion in 7

Question 10

explanation for microdeletion syndromes

Answer 10

NAHR recombination with low copy repeats

Question 11

47, XXY

Answer 11

Klinefelter syndrome; long limbs, physically normal until puberty, average intelligence

Question 12

45,X; 46,X,i;, 45,X/46,XX

Answer 12

Turner syndrome; short stature, deficient secondary sex characteristics at puberty, average intelligence

Question 13

46,XX male

Answer 13

female chromosomes with an SRY gene

Question 14

46, XY female

Answer 14

male chromosomes without the SRY gene