THE GENETIC-LOCUS FOR FREE SIALIC-ACID STORAGE DISEASE MAPS TO THE LONG ARM OF CHROMOSOME-6

Salla disease (SD), or adult-type free sialic acid storage disease, is an autosomal recessive lysosomal storage disorder characterized by im paired transport of free sialic acid across the lysosomal membrane and severe psychomotor retardation. Random linkage analysis of a sample o f 27 Finnish families allowed us to localize the SD locus to the long arm of chromosome 6. The highest lod score of 8.95 was obtained with a microsatellite marker of locus D6S286 at theta =.00. Evidence for lin kage disequilibrium was observed between the SD locus and the alleles of three closely linked markers, suggesting that the length of the cri tical region for the SD locus is in the order of 190 kb.