Narrowing candidate region for monosomy 9p syndrome to a 4.7-Mb segment at 9p22.2-p23

A 2-year-old boy with clinical manifestations of monosomy 9p syndrome and brown hair is described. G-banding and chromosome FISH studies demonstrated complex rearrangements involving seven breakpoints in chromosomes 2 and 9, which included a 6.6-Mb deletion at 9p22.2-p23. This, together with previous studies in the literature, narrowed the shortest region of overlap (SRO) for the syndrome to a 4.7-Mb interval. Candidate genes for trigonocephaly, mental retardation, and brown hair are discussed.