CGC Exam - Chromosome Abnormalities Exam
Questions And Answers
What is the most common aneuploidy? - Answer T21 (Down syndrome)
What percentage of fetuses with T21 have US findings? - Answer 50%
What are the 5 US findings commonly associated with T21? - Answer - Increased NT
- Absent nasal bone
- Cardiac anomalies (50%) (ex. atrioventricular septal defect (AVSD))
- Echogenic bowel
- Echogenic intracardiac focus (EIF)
What are the 4 features commonly associated with T21 after birth? - Answer - ID
- 10x higher risk of leukemia
- High risk for early-onset dementia
- GI anomalies (ex. congenital duodenal obstruction (CDO))
What percentage of pregnancies with T21 miscarry? - Answer 50-75%
What percentage of fetuses with T21 have full T21? - Answer 95%
What percentage of fetuses with T21 have T21 due to a translocation? - Answer 5%
What is the most common T21-associated translocation? - Answer 14;21
, What is the overall prevalence of T21? - Answer 1/800 births
What is the chance for T21 in 35 y.o. pregnancy carriers? - Answer 1/300
What is the chance for T21 in 40 y.o. pregnancy carriers? - Answer 1/100
What is the chance for T21 in 45 y.o. pregnancy carriers? - Answer 1/20
What is the chance for T21 in 50 y.o. pregnancy carriers? - Answer 1/5
What percentage of cases of T21 are in pregnancy carriers under 35 due to higher birth
rates? - Answer 90%
What percentage of fetuses with T13 (Patau syndrome) have US findings? - Answer 90%
What are the 6 US findings commonly associated with T13? - Answer - Midline facial
defects (ex. holoprosencephaly)
- Cardiac defects (ex. patent ductus arteriosus (PDA))
- Polydactyly
- Rocker bottom feet
- Clenched hands w/ overlapping fingers
- Increased NT
What percentage of newborns with T13 survive until their first birthday? - Answer 10%
(though this number is increasing due to medical advancements)
What is the second most common aneuploidy? - Answer T18 (Edwards syndrome)
Questions And Answers
What is the most common aneuploidy? - Answer T21 (Down syndrome)
What percentage of fetuses with T21 have US findings? - Answer 50%
What are the 5 US findings commonly associated with T21? - Answer - Increased NT
- Absent nasal bone
- Cardiac anomalies (50%) (ex. atrioventricular septal defect (AVSD))
- Echogenic bowel
- Echogenic intracardiac focus (EIF)
What are the 4 features commonly associated with T21 after birth? - Answer - ID
- 10x higher risk of leukemia
- High risk for early-onset dementia
- GI anomalies (ex. congenital duodenal obstruction (CDO))
What percentage of pregnancies with T21 miscarry? - Answer 50-75%
What percentage of fetuses with T21 have full T21? - Answer 95%
What percentage of fetuses with T21 have T21 due to a translocation? - Answer 5%
What is the most common T21-associated translocation? - Answer 14;21
, What is the overall prevalence of T21? - Answer 1/800 births
What is the chance for T21 in 35 y.o. pregnancy carriers? - Answer 1/300
What is the chance for T21 in 40 y.o. pregnancy carriers? - Answer 1/100
What is the chance for T21 in 45 y.o. pregnancy carriers? - Answer 1/20
What is the chance for T21 in 50 y.o. pregnancy carriers? - Answer 1/5
What percentage of cases of T21 are in pregnancy carriers under 35 due to higher birth
rates? - Answer 90%
What percentage of fetuses with T13 (Patau syndrome) have US findings? - Answer 90%
What are the 6 US findings commonly associated with T13? - Answer - Midline facial
defects (ex. holoprosencephaly)
- Cardiac defects (ex. patent ductus arteriosus (PDA))
- Polydactyly
- Rocker bottom feet
- Clenched hands w/ overlapping fingers
- Increased NT
What percentage of newborns with T13 survive until their first birthday? - Answer 10%
(though this number is increasing due to medical advancements)
What is the second most common aneuploidy? - Answer T18 (Edwards syndrome)
