Genetics Review - Final XLS in CSV form - Sheet1 Flashcards
What is the most common trisomy in abortuses?
Trisomy 16
What aneuploidy is seen with holoprosencephaly and midline facial defects?
Trisomy 13
Triple screen shows a normal AFP, normal HCG and a low E3. What condition is this associated with?
X-linked icthyoses and SLOS
What is the most common cause of CAH?
21 alpha hydroxylase deficiency
How do you treat the fetus is the mother has CAH?
Dexamthasone, starting at 7-8 weeks. To prevent virilization of female fetus
What karyotype is suggestive of uniparental disomy?
From any trisomy as a trisomic rescue
( i.e you have trisomy 13 on CVS, the fetus tries to save itself by losing chromosome 13 but loses the wrong one and gets a uniparental disomy)
Which maternal karyotype has the highest risk of Down syndrome?
21:21 Translocation (100% of live babies are T21, but of total gametes 50% would be monosomy 21)
What is the most common finding with Trisomy 21 on sono at 18-20 weeks?
Nuchal Fold
What is the most common finding of a term infant with Down syndrome?
- Simian crease
- Hypotonia
- LBW <2500gm
Hypotonia
Most common outcome if NT is increased?
Normal
What syndrome has coarctation of the aorta?
Turners
What condition with CF carries a poor prognosis?
Cor Pulmonale
Which syndrome has absent radius, polyhydramnios and hydronephrosis?
Thrombocytopenia absent radius (TAR) Syndrome
- can have kidney, heart and thrombocytopenia with absent radius
- both radii are missing but thumbs are present
Which is not related to non-disjunction in the mother?
- Turners
- Klienfelters
- XXX
Turners
The single X is maternal in origin in 70% of cases. Paternal is lost
Anomaly of what system is most commonly seen with diaphragmatic hernia ?
Cardiac
What is the risk of Down syndrome with a prior afected child?
1% or the age related risk, whichever is higher
Which condition is most likely associated with aneuploidy?
- Cardiac
- Omphalocele
Omphalocele
What pattern of inheritance is passed through maternal only?
Mitochondrial
Which maternal cardiac lesion is associated with the greatest fetal risk of transmission?
- AS
- MS
- VSD
- TOF
Aortic stenosis (15-18% risk of fetal transmission)
IHSS: 50%
Coarctation: 14%
Which condition is most likely to transmit to the fetus?
- ASD
- VSD
- Coarctation
- TOF
Coarctation
45XX, der(13,21)(q10q10) is associated with what?
Normal.
This is a balanced translocation on 13q;21q
What mechanisms result in uniparental disomy?
2 chromosomes inherited from one parent, trisomic rescue
Ex: Beckwith, Angelman, Prader-Willi
Amniotic fluid acetylcholinesterase is least helpful with what condition?
- Omphalocele
- Gastroschisis
- Congenital nephrosis
- Anencephaly
Congenital nephrosis
What should you do if cord insertion at 8 weeks is abnormal?
Repeat ultrasound because of physiologic herniation
Which situation is most likely to result in a fetus having T21?
- mom 45XX rob(14;21)
- dad 45XX rob(14:21)
Mom 10-15%
Dad: <5%
Which of the following is not associated with AMA? T21 T13 T18 45XO
45 XO
Which of the following is associated with coarctation of the aorta?
45 XO
As a class, what is the most common etiology for fetal malformations?
Genetic
Which karyotype is the result of a uniparental disomy?
A Trisomy - results in UPD from trisomic rescue
Fetus has cleft lip/palate, VSD, holoprosencephay. What is the most likely diagnosis?
T13
What is the most reliable ultrasound criteria for dating?
Cerebellum
Foot length