Trisomy 13

Incidence

 * 1/19,000 live births

Molecular Etiology

 * 75% Trisomy 13
 * Mostly Maternal Meiosis Errors


 * 20% Translocation
 * Mostly Robertsonian (t13;14)
 * 95% de novo, ~5% familial


 * 5% mosaic
 * Often Less Severe
 * Variable Phenotype

Associated Birth Defects

 * Holoprosencephaly
 * Cleft Lip & Palate
 * Cyclopia
 * Omphalocele
 * Cardiac Defects

Facial Features

 * Hypotelorism
 * Sloping Forehead
 * Microcephaly
 * Microopthalmia
 * Bulbous nose
 * Micrognathia
 * Scalp Lesions

Extremities

 * Polydactyly

Neurological

 * Intellectual Disability
 * Developmental Delay

Prognosis

 * Mortality
 * <1 month = 82%
 * <1 year = 92%
 * 3+ years = Exceptionally Rare

Recurrence Risk

 * Trisomy 13 = <1%
 * Translocation
 * Familial
 * maternal = 1%
 * paternal = <1%