title: Discordant monozygotic twins with trisomy 13.
abstract: Monozygotic twins with typical trisomy 13 are reported. Despite an identical karyotype, the twins were dimorphic for the presence of an omphalocele. Reasons for the rarity of MZ twins with trisomy 13 are presented. It is suggested that the presence of a chromosomal abnormality in MZ twins may predispose to dimorphism.
mesh_terms: D002675:Child, Preschool; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002901:Chromosomes, Human, 13-15; D004200:Diseases in Twins; D006554:Hernia, Umbilical / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D014314:Trisomy; D014427:Twins; D014430:Twins, Monozygotic