Extra's Flashcards
What is the karyotype of Trisomy 18 (Edwards syndrome)?
47,XX,+18 (female) or 47,XY,+18 (male).
What is the incidence of Trisomy 18?
Approximately 1 in 3,300 live births.
What is the underlying cause of Trisomy 18?
Meiotic nondisjunction leading to an extra copy of chromosome 18.
What is the typical gender distribution of Trisomy 18?
More common in females than males.
What are characteristic facial features of Trisomy 18?
Low-set ears, micrognathia (small jaw), prominent occiput, microcephaly, broad nose, cleft lip and palate.
What hand abnormality is associated with Trisomy 18?
Clenched fists with flexion contractures and overlapping fingers (3rd and 4th fingers over 2nd and 5th).
What is the classic foot abnormality seen in Trisomy 18?
Rocker-bottom feet (convex plantar deformity with vertical talus and prominent calcaneus).
What are common congenital heart defects in Trisomy 18?
Ventricular septal defect (VSD), atrial septal defect (ASD), and tetralogy of Fallot.
What internal organ malformations are seen in Trisomy 18?
Diaphragmatic hernia, horseshoe kidneys, ureteral anomalies, myelomeningocele, and omphalocele.
What is the cognitive impact of Trisomy 18?
Severe intellectual disability.
What findings suggest Trisomy 18 on second-trimester quadruple screening?
Decreased AFP, decreased β-hCG, decreased estriol, normal or decreased inhibin A.
What is the prognosis for infants with Trisomy 18?
Poor; only ~13% survive past 12 months of age.
What mnemonic helps remember Trisomy 18 features?
PRINCE Edward: Prominent occiput, Rocker-bottom feet, Intellectual disability, Nondisjunction, Clenched fists, low-set Ears, and chromosome 18.
