A/51

Question 1

Types of abnormalities that cause cytogenic disorders (2)

Answer 1

• numerical abnormalities

- structural abnormalities

Question 2

Types of numeric abnormalities (4)

Answer 2

• Euploid
• Polyploidy
• Aneuploidy
• Mosaicism

Question 3

What usually causes aneuploidy?

Answer 3

non disjunction of a homologous pair of chromosomes

Question 4

Types of structural abnormalities (4)

Answer 4

• Translocation
• Isochromosomes
• Deletion
• Inversions

Question 5

What is a robertsonian translocation

Answer 5

Break occurs at the centromere of an acrocentric chromosome, creating one long chromosome and one short chromosome

Question 6

What is an isochromosome?

Answer 6

centromere divides horizontally, not vertically, so the final chromosome is made of the 2 long arms / 2 short arms

Question 7

Which has the worst affect? absence / excess?

Answer 7

Absence : deletion, monosomy in autosomal (not sex) chromosomes

Question 8

Prevalence of trisomy 21

Answer 8

1/700 births

Question 9

What has a strong influence on the prevalence of trisomy 21?

Answer 9

Maternal age : over the age of 45, 1/25 births are affected

Question 10

5 autosomal abnormalities

Answer 10

1. Trisomy 21
2. Trisomy 18 - edwards
3. Trisomy 13 - patau
4. Cri du chat syndrome
5. 22q11.2 deletion syndrome - digeorge

Question 11

Prevalence of trisomy 18

Answer 11

1 / 8.000 births

Question 12

5 anatomical characteristics of Trisomy 18 / edwards syndrome

Answer 12

• mental retardation
• congenital heart defects
• renal malformation
• overlapping fingers
• short neck

Question 13

Prevalence of trisomy 13

Answer 13

1 / 15.000 births

Question 14

5 anatomical characteristics of trisomy 13 / patau syndrome

Answer 14

• polydactyly
• microcephaly
• mental retardation
• cleft lip / palate
• heart defects

Question 15

What is cri du chat syndrome?

Answer 15

deletion of short arm of chromosome 5

Question 16

What does 22q11.2 deletion cause? (4)

Answer 16

• congenital heart disease
• facial abnormalities
• developmental delay
• t cell immunodeficiency

Question 17

Karyotype for klinefelter syndrome

Answer 17

47, XXY

Question 18

Karyotype turner syndrome

Answer 18

45, XO

Question 19

Caracteristics of klinefelter syndrome (4)

Answer 19

• elongated body appearance
• reduced body and facial hair
• gynecomastia
• infertility

Question 20

Characteristics of turner syndrome (5)

Answer 20

• growth retardation
• neck swelling
• lymphedema of hands of feet
• congenital defects
• autoantibody hypothyroidism