Trisomy 18Comments
parentGenetic disease
siblingsAndrogen InsensitivityBalanced RearrangementCancer geneticsChromosome Number AbnormalitiesCystic FibrosisDown SyndromeDuchenne Muscular DystrophyFragile X SyndromeHemoglobinopathyHuntington DiseaseHurler SyndromeHyperphenylalaninemiamRNA Splicing AberrationsNondisjunctionPenis-At-Twelve SyndromeRelative RiskSickle Cell DiseaseSpinal Muscular AtrophyTay-Sachs DiseaseThalassemiaTriplet Repeat ExpansionsTrisomy 13Unbalanced RearrangementUniparental Disomy

Trisomy 18

Trisomy 18 is one of only three thoroughly-studied viable non-mosaic autosomal disorders (the others being trisomies 18 and 21), all of which result in stunted growth, mental retardation and multiple congenital deformities. Trisomy 18 frequently arises via translocation of all or most of Chromosome 18. Trisomy 18's phenotype is mental retardation in all cases, with most cases also involving: severe heart malformation; a receded jaw (overbite); low-set malformed ears; rocker-like feet; and hypertonia, usually leading to unique clenched fists characteristic of trisomy 18.