Down Syndrome and Other Abnormalities of Chromosome Number

Question 1

Abnormal cells that do not contain a multiple of haploid number of chromosomes

Answer 1

Aneuploid cells

Question 2

Most common and clinically significant type of human chromosome abnormality

Answer 2

Aneuploidy

Question 3

MC cause of aneuploidy

Answer 3

Nondisjunction

Question 4

Characeterized by the presence of 3 chromosomes

Answer 4

Trisomy

Question 5

MC form of aneuploidy

Answer 5

Trisomy

Question 6

Technique used for rapid diagnosis in the prenatal detection of common fetal aneuploidies

Answer 6

FISH

Question 7

MC numerical abnormalities in live born children (3)

Answer 7

1) T21 Down’s 2) T18 Edwards 3) T13 Patau

Question 8

MC type of trisomy in liveborn infants

Answer 8

Trisomy 21

Question 9

T/F The occurrence of Trisomy 21 and other trisomies increased with advanced age

Answer 9

T

Question 10

Age at which occurrence of Trisomy increases

Answer 10

> 35 y/o

Question 11

___% of spontaneous abortuses have chromosomal abnormalities

Answer 11

50%

Question 12

MC chromosomal abnormality in abortuses

Answer 12

45,X (Turner)

Question 13

___% of 45,X are foetuses are spontaneously aborted

Answer 13

99

Question 14

Features in NB and children that suggest the presence of a chromosome anomaly

Answer 14

1) LBW/SGA 2) Failure to thrive 3) Developmental delay 4) 3 or more congenital malformations

Question 15

MC genetic cause of moderate mental retardation

Answer 15

Down syndrome

Question 16

T/F Individuals affected with Down syndrome are more prone to CHD

Answer 16

T

Question 17

A complication of Down syndrome that occurs as early as the 4th decade

Answer 17

Alzheimer disease-like dementia

Question 18

T/F Developmental delay is universal in individuals with Down syndrome

Answer 18

T

Question 19

Area of development that is relatively spared in Down syndrome

Answer 19

Social development

Question 20

All women should be offered screening for Down syndrome when

Answer 20

2nd trimester

Question 21

Maternal serum tests used to screen Down Syndrome (4)

Answer 21

1) Free beta HCG 2) Unconjugated estriol 3) Inhibin 4) alpha fetoprotein

Question 22

The origin of supernumerary chrome 21 in children with Down syndrome is

Answer 22

Maternal (97%)

Question 23

Fusions in Down syndrome, found at the centromere between chromosomes 13, 14, 15, 21, and 22

Answer 23

Robertsonian translocations

Question 24

MC abnormality of chromosomal number

Answer 24

Trisomy 21

Question 25

Nondysjunctional event in Down syndrome pregnancy occurs during

Answer 25

Maternal meiosis phase I

Question 26

T/F In approx 95% of cases of Down Syndrome, there are 3 copies of chromosome 21

Answer 26

T