A 4-Mb BAC/PAC contig and complete genomic structure of the GPC5/GPC6 genecluster on chromosome 13q32

The glypicans compose a family of glycosylphosphatidylinositol-anchored hep aran sulfate proteoglycans that may play a role in the control of cell divi sion and growth regulation. So far, six members (GPC1-6) of this family are known in vertebrates. We report the construction of a high-resolution 4 Mb sequence-ready BAC/PAC contig of the GPC5/GPC6 gene cluster on chromosome region 13q32. The contig indicates that, like the GPC3/GPC4 genes on Xq26, GPC5 and GPC6 are arranged in tandem array. Both GPC5 and GPC6 are very lar ge genes, with sizes well over 1 Mb. With a size of approximately 2 Nib, GP C5 would be the second largest human gene identified to date. Comparison of the long range gene organisation on 13q and Xq, suggests that these chromo somes share several regions of homology. Mutations and deletions affecting GPC3 are associated with the Simpson-Golabi-Behmel overgrowth syndrome. Mut ational analysis of GPC5 and GPC6 in 19 patients with somatic overgrowth fa iled to reveal pathologic mutations in either of these genes, but identifie d several coding region polymorphisms. (C) 2001 Elsevier Science B.V. /Inte rnational Society of Matrix Biology. All rights reserved.