ISOLATION OF BAC CLONES SPANNING THE XQ22.3 TRANSLOCATION BREAKPOINT IN A LISSENCEPHALY PATIENT WITH A DE-NOVO X-2 TRANSLOCATION

X linked lissencephaly and subcortical band heterotopia (XLIS/SBH) is a disorder of cortical development, which causes classical lissencepha ly with severe mental retardation and epilepsy in hemizygous males and SBH associated with milder mental retardation and epilepsy in heteroz ygous females. Here we report the fine mapping of a breakpoint involve d in a de novo X;autosomal balanced translocation (46,XX,t(X;2) (q22.3 ;p25.1)) previously described in a female with classical lissencephaly . We constructed a complete 490 kb BAC contig around the Xq22.3 breakp oint with 11 novel STSs and isolated three BAC clones spanning the bre akpoint. This mapping information and BAC contig will be useful in the detailed characterisation of the XLIS gene and other contiguous genes which may also be involved in brain development or function.