First identified Korean family with Sotos syndrome caused by a novel intragenic mutation in NSD1.

Sotos syndrome (SS) is a congenital overgrowth syndrome. NSD1 mutations are identifiable in most SS patients. There have been a few reports of familial inheritance of SS worldwide, but no familial cases have been reported in Korea. A 6-month-old girl had tall stature and macrocephaly with mild ventricular enlargement, and showed mild delay in motor and language development. Her mother also had tall stature and a long narrow face. The baby and her mother were suspected of having familial SS. Chromosome 5q35 microdeletion was first ruled out by fluorescence in situ hybridization analysis, and direct sequencing of NSD1 revealed a novel heterozygous mutation in exon 22 (c.6356delA; p.Asp2119Valfs*31). This report describes, for the first time, a Korean family with two generations of SS resulting from a novel intragenic NSD1 mutation.