Repro 14 - Chromosomal Disorder

Question 1

What is Fragile X syndrome?

Answer 1

X-linked. Trinucleotide repeat. Affects the expression of FMR1 gene; codes for FMRP, a cytoplasmic protein found in brain and testes, and is involved mRNA translation of axons and dendrites. Second most common cause of genetic intellectual disability. Macroorchidism, long face, large jaw, large E-verted ears. Mitral valve prolapse.

Question 2

What is the most common cause of intellectual disability Overall?

Answer 2

Fetal alcohol syndrome.

Question 3

What is the most common of the trisomies?

Answer 3

Down syndrome.

Question 4

What is Down syndrome?

Answer 4

Trisomy 21. Causes intellectual disability (most common genetic cause), most common of trisomies, flat faces, prominent epicanthal folds, simian crease, increased gap b/w 1st and 2nd toe. Duodenoal atresia. Endocardial cushion defects. Increased risk of ALL more than AML [All fall Down]. Increased Alzheimer disease. Possibly polycythemia.

Question 5

What would be the findings of a quad screen with a fetus w/ Down syndrome?

Answer 5

Decreased AFP. Increased Beta-hCG. Decreased estriol. Increased A.

Question 6

What would ultrasound show in a fetus w/ Down syndrome?

Answer 6

Increased in nuchal translucency in the first trimester; can also be seen in Turner syndrome.

Question 7

What is the cause of 95% of Down syndrome?

Answer 7

Myotic nondisjunction of the homologous chromosome; associated w/ advancing maternal age.

Question 8

What is Robertsonian translocation?

Answer 8

A nonreciprocal chromosomal translocation that commonly involves chromosome pairs; commonly when the long arms of two acrocentric chromosomes fuse at the centromeres and the two short arms are lost. In the first child, it will be okay but in the next generation, the child could have 3 copies of chrom 21, causing Down syndrome.

Question 9

What is Edwards syndrome?

Answer 9

Trisomy 18. Causes Rocker bottom feet, severe intellectual disa, micronanthia, clinched hands, prominent occiput, death occurs before 1 year.

Question 10

What would you see in a quad screen with a fetus with Edwards syndrome?

Answer 10

Decreased beta-hCG. Decreased AFP. Decreased estriol. Normal inhibin A.

Question 11

What is Patau syndrome?

Answer 11

Trisomy 13. The rarest of the trisomies. Severe intellectual disa, Rocker bottom feet, microcephaly. Cleft lip and palate. Holoprosencephaly and a single midline eye. Polydactyly and congenital heart disease.

Question 12

What would be the pregnancy screening findings with a fetus w/ Patau syndrome?

Answer 12

Decreased beta-hCG. Decreased PAPP-A. Increased nuchal translucency.

Question 13

What trisomy would be suspected in a prenatal screening with Decreased AFP, increased B-hCG, Decreased estriol, and increased Inhibin A?

Answer 13

Trisomy 21.

Question 14

What trisomy would be suspected in a prenatal screening with decreased AFP, decreased B-hCG, decreased estriol, and normal Inhibin A?

Answer 14

Trisomy 18.

Question 15

What trisomy would be suspected in a prenatal screening with Decreased B-hCG, Decreased pregnancy associated plasma protein A (PAPP-A) and increased nuchal translucency?

Answer 15

Trisomy 13.

Question 16

What is Klinefelter syndrome?

Answer 16

Extra sex chromosome. 47 XXY. Males are infertile. Dysgenesis of seminiferous tubules. Female pattern of body hair. Decrease in inhibin. Increase in FSH.

Question 17

What is Turner syndrome?

Answer 17

45XO. Missing a sex chromosome, therefore no Barr bodies. Short stature, webbed neck, shield test, low set ears, gonadal dysfunction, amenorrea and infertility, “streak ovaries”. Most common cause of primary amenorrea. Bicuspid aortic valve, and coarctacion of the aorta. Decreased estrogen, increase in LH and FSH.

Question 18

What is the most common cause of primary amenorrhea?

Answer 18

Turner syndrome.

Question 19

What are the symptoms of Double Y male?

Answer 19

47XYY. Phenotypically normal. Very tall, severe acne. Antisocial behavior (criminal inmates). Normal fertility.

Question 20

What is Cri-du-Chat syndrome?

Answer 20

Microcephaly. Moderate to severe mental disa, high-pitched crying and mewing. Epicanthal folds, cardiac abnormalities.

Question 21

What is William Syndrome? What is the cause of it?

Answer 21

Distinctive elf-like face. Intellectual disa, hypercalcemia due to hypersensitivity to vitamin D, good verbal skills. Caused by microdeletion of the long arm of chromosome 7.

Question 22

What is 22q11 Deletion Syndromes?

Answer 22

[CATHC-22] Cleft lip. Abnormal faces. Thymic aplasia (causes T-cell deficiency). Hypocalcemia (caused by parathyroid hypoplasia). Cardiac defects. Not all DiGeorge patients have 22q11 deletion syndromes but most do (90%).

Question 23

What prenatal ultrasound finding is a clue that the fetus may have Down Syndrome?

Answer 23

Nuchal translucency.

Question 24

What gene is affected in Fragile X syndrome?

Answer 24

FMR1.

Question 25

RFF: Most common genetic cause of intellectual disability.

Answer 25

Trisomy 21.

Question 26

RFF: Second most common genetic cause of intellectual disability.

Answer 26

Fragile X syndrome.

Question 27

RFF: Horseshoe kidney, congenital heart defects, streak ovaries, and cystic hygroma.

Answer 27

Turner syndrome.

Question 28

RFF: Rocker Bottom feet, clenched hands, microcephaly w/ prominent occiput and small jaw.

Answer 28

Trisomy 18.