Prenatal Genetics Flashcards
Cystic fibrosis
CFTR; AR
progressive lung disease, pancreatic cysts
1 in 2,000 affected in white populations
1 in 23-35 are carriers in white/US population
Advanced paternal age
40-50 years old
Risks:
-Increased de novo substitutions, causing e.g.,: achondroplasia, Pfeiffer, Crouzon, Apert, Thanatophoric dysplasia
-Increased risk of ASD, bipolar, schizophrenia
Advanced maternal age
35 years old at conception
Risks: aneuploidy
Background birth defect risk
2-6%
BIRTH DEFECTS ARE NOT PREVENTABLE (exception: NTDs and folate)
Cleft lip/palate
Gen pop risk: 0.1%
Recurrence risk: 4-8%
Males are more likely to have isolated cleft lip/palate (2:1 ratio)
CHD
Gen pop risk: 1%
Recurrence risk: 3-5%
Open neural tube defect (e.g., anacephaly or spina bifida)
Gen pop risk: .1%
Recurrence risk: 1-3%
Clubfoot
Gen pop risk: .1%
Recurrence risk: 2-7%
Increased NT
Can be seen with Down Syndrome or Noonan
If trisomy 21 is negative, evaluate with fetal echo
Fetal anatomy scan
At 20 weeks
Can only detect trisomy 21 50% of the time
Banana sign
shape of the cerebellum owing to caudal displacement
NOT GOOD
Common teratogens
Valproic acid (VPA) for seizures Ace inhibtors Accutane Retinoids Occupational exposures
Most common causes of recurrent pregnancy losses
Aneuploidies: Monosomy X, T16, T22, triploidy
Chromosomal rearrangements
Anatomical abnormalities, hormone imbalances, teratogens
Most common causes of stillbirth
Unknown, placenta/cord issues, aneuploidy, birth defects, teratogens
Most common infertility causes
Unknown, chromosome abnormalities, single gene disorders, ovulatory dysfunction, reproductive organ issues (e.g. bilateral absence of congenital vas deferns associated w/ CF), semen abnormalities, teratogens
