Chromosomal Disorders

Question 1

Down Syndrome increased risks

Answer 1

• -Duodenal atresia
• -Hirschprung disease
• -Endocardial cushion defects
• -Increased ALL and AML
• -Increased Alzheimer disease
• -Polycythemia
• -Intellectual disability

Question 2

What is the most common cause of Down Syndrome?***

Answer 2

Maternal nondisjunction of homologous chromosomes during anaphase of meiosis 1

Question 3

Down Syndrome lab findings on quad screen***

Answer 3

• -Decreased AFP
• -Increased beta HCG
• -Decreased estriol
• -Increased inhibin A

Question 4

Robertsonian Translocation

Answer 4

• -Chromosomal translocation that commonly involves chromosome pairs 13, 14, 15, 21, and 22
• -2 acrocentric chromosomes fuse at the centromere and the 2 short arms are lost.

Question 5

Edwards Syndrome (Trisomy 18) findings

Answer 5

• -Severe intellectual disability
• -Rocker-bottom feet
• -Micrognathia
• -Low-set ears
• -Clenched hands with overlapping fingers
• -Prominent occiput
• -Congenital heart disease
• -Death within one year

Question 6

Edwards Syndrome lab findings on quad screen

Answer 6

–Decreased beta HCG, estriol, inhibin A and AFP

Question 7

Patau Syndrome (trisomy 13) findings

Answer 7

• -Severe intellectual disability
• -Rocker-bottom feet
• -Microphthalmia
• -Microcephaly
• -Cleft lip/palate
• -Holoprosencephaly
• -Polydactyly
• -Congenital heart disease
• -Cutis aplasia
• -Death within one year.

Question 8

Patau syndrome lab findings during first trimester

Answer 8

• -Decreased beta HCG

- -Decreased PAPP-A

Question 9

Cri-du-Chat deletion***

Answer 9

–Congenital microdeletion of short arm on chromosome 5

Question 10

Cri-du-Chat findings***

Answer 10

• -Microcephaly
• -Moderate to severe intellectual disability
• -High-pitched crying/mewing
• -Epicanthal folds
• -Cardiac abnormalities (VSD)

Question 11

Williams Syndrome deletion

Answer 11

–Microdeletion of long arm of chromosome 7 (deleted region includes elastin gene)

Question 12

Williams Syndrome findings

Answer 12

• -Distinctive “elfin” facies
• -Intellectual disability
• -Hypercalcemia (increased sensitivity to Vit D)
• -Well-developed verbal skills
• -Extreme friendliness with strangers
• -Cardiovascular problems

Question 13

22q11 deletion syndromes

Answer 13

• -Cleft palate
• -Abnormal facies
• -Thymic aplasia–>T cell deficiency
• -Cardiac defects
• -Hypocalcemia (secondary to parathyroid aplasia)

Question 14

Digeorge syndrome

Answer 14

Thymic, parathyroid, and cardiac defects related to 22q11 deletion

Question 15

Velocardiofacial syndrome

Answer 15

Palate, facial and cardiac defects related to 22q11 deletion

Question 16

Double Y males

Answer 16

• -Phenotypically normal
• -Very tall
• -Normal fertility
• -May be associated with severe acne, learning disability, autism spectrum disorders