ASSIGNMENT OF THE GENE RESPONSIBLE FOR CYSTINURIA (RBAT) AND OF MARKERS D2S119 AND D2S177 TO 2P16 BY FLUORESCENCE IN-SITU HYBRIDIZATION

We have established rBAT (named as SLC3A1 in the Genome Data Base) as a gene responsible for cystinuria, a heritable disorder of amino acid transport. The cystinuria locus has been mapped by linkage between mic rosatellite markers D2S119 and D2S177. Fluorescene in situ hybridizati on (FISH) either with Alu-polymerase-chain-reaction (PCR)-amplified se quences of a yeast artificial chromosome (YAC) containing the rBAT gen e or with rBAT-specific PCR-amplified genomic fragments, and chromosom e G-banding have cytogenetically mapped rBAT to 2p16.3. In order to co rrelate the physical and genetic information on cystinuria, we have pe rformed FISH with combinations of Alu-PCR-amplified sequences from YAC s containing rBAT or the D2S119 and D2S177 loci. In all cases, a fused signal is obtained that demonstrates their close physical location; t his allows the assignment of rBAT, cystinuria and their linked markers , D2S119 and D2S177, to 2p16.