Chromosomal abnormalities

Question 1

Chromosomal abnormalities

Answer 1

Most chromosomal abnormalities will result in spontaneous abortions, except Trisomy 21, 18, 13 and Turner’s syndrome

Question 2

Pertinent risk factor of trisomy 13, 18, 21

Answer 2

Increasing maternal age
*As woman ages, follicles age, oocytes age, more chromosomal deformities

Question 3

Trisomy 21 aka Down’s syndrome

Answer 3

NOT hereditary
A/w increasing maternal age
Meiosis error

Question 4

Features of trisomy 21, 18, 13 on ultrasound

Answer 4

Thickened nuchal translucency
Absent nasal bone

Question 5

Most important chromosomal abnormality to screen for

Answer 5

Trisomy 21

Question 6

Note: Trisomy 13 & 18 often have structural abnormalities detectable on ultrasound scan, unlike 21

Answer 6

-

Question 7

Screening for trisomy 21

Answer 7

OFFER combined first trimester screening in a patient presenting in 1st trimester
Consider OFFER NIPT straight up if patient has certain indications eg >35yo etc

Question 8

Trisomy 18 aka Edward’s syndrome

Answer 8

• 2nd most common autosomal trisomy
• F:M = 3:1
• Most will die in utero
• 50% of infants die within first 2 weeks of life  
• 5-10% survive the first year

Question 9

Trisomy 13 aka Patau syndrome

Answer 9

• Usually die in utero, or within first day/ few weeks of life  
• Only 5-10% live past the first year

Question 10

Risk factor of Turner’s syndrome (XO)

Answer 10

Increasing paternal age

Question 11

Ultrasound features of Turner’s syndrome

Answer 11

Highly thickened NT
Horseshoe kidney
Coarctation of aorta

Question 12

Types of chromosomal abnormalities

Answer 12

Aneuploid: Unbalanced set of chromosomes
Monosomic: Loss of single chromosome copy
Polysomic: Extra copies of single chromosome