Prenatal Genetics

Question 1

define polyploid vs. aneuploid

Answer 1

polyploid: numerical deviation involving an exact multiple of the haploid number (n = 23)
aneuploid: numerical deviation NOT involving an exact multiple of the haploid number (i.e., trisomy 18, where there are there copies of only chromosome 18)

Question 2

____ triploidy: extra chromosome set of maternal origin

____ triploidy: extra chromosome set of paternal origin

Answer 2

diGYNic; diANDRic

Question 3

Down syndrome: genetic change, clinical findings

Answer 3

trisomy 21; intellectual disability, flat facies, prominent epicanthal folds, single palmar crease, heart malformations, GI abnormalities

Question 4

dx: neonate with rocker-bottom feet, micrognathia, microcephaly

Answer 4

trisomy 18 (Edwards syndrome)

Question 5

trisomy 18 (Edwards syndrome): clinical findings

Answer 5

severe intellectual disability, rocker-bottom feet, micrognathia, microcephaly

Question 6

trisomy 13 (Patau syndrome): clinical findings

Answer 6

severe intellectual disability, microphthalmia, polydactyly, cleft lip/palate, brain and heart malformations

Question 7

Turner syndrome: genetic change

Answer 7

monosomy X

Question 8

what is a Roberstonian translocation?

Answer 8

short arms of two chromosomes are lost and the remaining long arms are joined

Question 9

what 3 types of drugs can cause fetal defects?

Answer 9

retinoic acid (for acne), valproic acid (anticonvulsant), SSRIs (only in 3rd trimester)

Question 10

dx: intellectual disability, long face with long jaw, large everted ears, autism

Answer 10

Fragile X syndrome

Question 11

Fragile X syndrome: pathogenesis, clinical features

Answer 11

trinucleotide repeats within the X chromosome; intellectual disability, long face with long jaw, large everted ears, autism