Aneuplodies

Question 1

Trisomy 21

Answer 1

47,XX +21 or 47,XY +21
1 in 185
ID, round face, macroglossia, almond eyes, upslanting palpebral fissures, CHD (50%), excess nuchal folds, shorter limbs, simian crease, increased (15x) Leukemia risk
4% due to Robertsonian translocation
Rare causes: 21q21 translocation, partial trisomy 21 (missing part of q arm)

Question 2

Trisomy 18

Answer 2

Cleft lip/palate, rocker bottom foot, overlapping fingers

Question 3

Trisomy 13

Answer 3

Cleft lip/palate

Question 4

Turner syndrome

Answer 4

50% 45,X
25% structural abnormality of X (e.g., isochromosome)
25% 45,X mosaicism
1 in 2500-4000
Short stature, webbed neck, gonadal dysgenesis, infertility, aortic dilation, bicuspid aortic valve, coarctation of the aorta

Question 5

Triple XXX

Answer 5

47,XXX
1 in 1000 (most common F chr abn).
Likely underdiagnosed due to mild nature.
Tall stature, mild LD and DD, behavioral (depression, anxiety, ADHD), epicanthal folds, hypotonia, clinodactyly, seizures, renal/genitourinary abnormalities, premature ovarian failure.

Question 6

Robertsonian translocation

Answer 6

Acrocentric fusion of extra chr21 to another chromosome (typically chr 13, 14, and more).
Causes Down Syndrome
Parents may be carriers; 4% recurrence risk?