Efficient Construction of a Physical Map by Fiber-Fish of the CLN5 Region: Refined Assignment and Long-Range Contig Covering the Critical Region on 13q22

The variant form of late infantile neuronal ceroid lipofuscinosis (vLINCL, locus definition CLN5) represents a progressive brain disease with autosomal recessive inheritance. We have previously assigned the CLN5 locus to chromosome 13q21.1–q32 between markers D13S160 and D13S162 by linkage analysis in Finnish families. The information on ancient recombination events obtained from linkage disequilibrium provided an efficient tool for further refining the assignment of the CLN5 locus. Isolation of two novel (CA)nmarkers, COLAC1 and AC224, resulted in a dramatic restriction of the critical DNA region. We utilized the Fiber-FISH technique to orient and order the large DNA clones isolated by STSs and were able to eliminate almost totally the restriction digestion and PFGE step in the construction of the long-range DNA contig. Both linkage disequilibrium data and Fiber-FISH analyses assigned the CLN5 locus to a well-defined 200-kb region. Here we report a complete physical map of about 350 kb covering the critical chromosomal region of CLN5, which will facilitate the final isolation of the CLN5 gene.