The first Japanese familial sotos syndrome with a novel mutation of the NSD1 gene

Sotos syndrome is caused by the haploinsufficiency of the NSD1 gene located in5q35. More than 70% of the Japanese cases carry microdeletions encompassing ofthis gene, while point mutations are common in Caucasians. Only 15 familial cases ofSotos syndrome have been reported and all cases shown to have not microdeletions butpoint mutations. We identified the first Japanese familial case (mother and 3children). They carry the same mutation at splice donor site of intron 13(IVS13+1G>A), which results in the in-frame skipping of exon 13. This is also the firstfamilial case caused by the mutation of the splice donor site. Each member of thisfamily showed variable phenotypes and mental development. The present report willcontribute to further understanding of genotype-phenotype correlation in Sotossyndrome