A provisional transcript map of the spinal muscular atrophy (SMA) critical region.

YACs from the region containing the spinal muscular atrophy (SMA) locus at 5q12 have been used as probes in a direct screening of cDNA libraries to isolate 8 cDNAs, mapped to different YAC fragments. Three clones showed complete identity to the genes for cyclin B1 (CCNB1), the p44 subunit of the transcription factor BTF2 (BTF2p44), and cofilin (CFL). Two clones showed partial identity to the beta-glucuronidase gene (GLCB) and a rat integral membrane glycoprotein gene (RNINMEGLA). CFL turned out to have been identified by a pseudogene sequence. Related sequences occurred on other chromosomes. CCNB1 and BTF2p44 were given an exact location. The GLCB-like gene and the RNINMEGLA-like gene detected loci on both 5q and 5p. The remaining three cDNA clones were localized to the SMA region only. Their sequences did not show identity to any gene for which a function is already known. Two of them have now turned out to be identical to recently reported candidate genes for SMA.