Features of trisomy 18 and 18p-syndromes in an infant with 46, XY, i(18q)

Abstract
An isochromosome for the long arm of chromosome number 18 ‐ 46, XY, i(18q) ‐ was found in an infant who had features of both trisomy 18 and 18p– syndromes. Findings compatible with trisomy 18 included postmature delivery, prominent occiput, severe congenital heart disease, overlapping fingers, and rocker‐bottom feet. Those of 18p– syndrome, which frequently resembles Turner syndrome, were downward obliquity to the palpebral fissures, short, webbed neck, low posterior hairline, and widely‐spaced nipples. The infant died of heart failure at 3.5 months of age. Parental karyotypes were normal.