GENETIC-LINKAGE ANALYSIS OF A VARIANT OF JUVENILE-ONSET NEURONAL CEROID-LIPOFUSCINOSIS WITH GRANULAR OSMIOPHILIC DEPOSITS

A number of variant forms of the neuronal ceroid lipofuscinoses (NCL) have been described and remain unmapped. The genes for infantile (CLN1 ), juvenile (CLN3) and Finnish-variant late-infantile (CLN5) have prev iously been mapped to chromosome regions 1p32, 16p12 and 13q21.1-32 re spectively. The locus for a Variant form of juvenile onset NCL charact erised by cytosomal granular osmiophilic deposits (GROD) has been excl uded from the CLN3 region of chromosome 16. This study describes the o utcome of genetic linkage analysis in four families with this Variant at the loci for the CLN1 and CLN5 genes. Using highly informative micr osatellite markers tightly linked to the CLN5 locus we have excluded t he JNCL variant with GROD from this region. Marker typing across the C LN1 region suggests that JNCL with GROD may be an allelic variant of i nfantile NCL.