A 2-MB YAC CONTIG ENCOMPASSING 3 LOCI (DXF34, DXS14, AND DXS390) THATLIE BETWEEN XP11.2 TRANSLOCATION BREAKPOINTS ASSOCIATED WITH INCONTINENTIA PIGMENTI TYPE-1

We demonstrate that all the repeat elements representing the conserved loci DXF34 and DXS390 lie between the X;9 and the X;17 translocation breakpoints associated with incontinentia pigmenti type 1 (IP1). Seque nce-tagged sites (STSs) at DXF34S1, DXS14, and DXS390 have been used t o isolate YAC clones containing these loci, and a contig of approximat ely 2 Mb has been constructed. Patterns of hybridization observed in t he YAC clones indicate that DXS390 comprises two distinct regions (A a nd B). The STS at DXS390 detects the A region and includes a polymerph ic CA repeat (PIC = 0.25). This expansion of the cloned region around DXF34 and DXS390 will enable the isolation of additional conserved seq uences that will help in understanding both the lesions underlying the pathogenesis of IP1 and the size and extent of the man-mouse homologo us block defined by DXF34. (C) 1994 Academic Press, Inc.