title: Monozygotic twins discordant for partial trisomy 1.
abstract: A 25-year-old primigravida delivered monozygotic twins discordant for multiple anomalies and partial trisomy 1 mosaicism. The phenotype of partial trisomy 1 includes craniofacial, central nervous system, and ocular anomalies. The most likely explanation for these findings is that the translocation occurred after twinning occurred. This observation emphasizes that monozygotic twins are not necessarily genetically identical. They are identical at conception, but subsequent mutation and rearrangement of the genome may cause substantial phenotypic differences.
authors.affiliation: Department of Obstetrics and Gynecology, Biological Sciences Research Center, University of North Carolina, Chapel Hill.
authors.forename: W J
authors.initials: WJ
authors.lastname: Watson
authors.forename: V L
authors.initials: VL
authors.lastname: Katz
authors.forename: S G
authors.initials: SG
authors.lastname: Albright
authors.forename: K W
authors.initials: KW
authors.lastname: Rao
authors.forename: A S
authors.initials: AS
authors.lastname: Aylsworth
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D000328:Adult; D002878:Chromosomes, Human, Pair 1; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009030:Mosaicism / Q000235:genetics; D010641:Phenotype; D011247:Pregnancy; D014178:Translocation, Genetic / Q000235:genetics; D014314:Trisomy; D014430:Twins, Monozygotic / Q000235:genetics*; D014998:Y Chromosome