THE SPINAL MUSCULAR-ATROPHY GENE REGION AT 5Q13.1 HAS A PARALOGOUS CHROMOSOMAL REGION AT 6P21.3

Paralogous regions are duplicated segments of chromosomal DNA that hav e been acquired during the evolution of the genome. Subsequent diverge nt evolution of the genes within paralogous regions can lead to the fo rmation of gene families. Here, we report the identification of a regi on on Chromosome (Chr) 6 at 6p21.3 that is paralogous with the Spinal Muscular Atrophy (SMA) gene region on Chr 5 at 5q13.1. Partial charact erization of this region identified nine sequences all of which are hi ghly homologous to DNA sequences of the SMA gene region at 5q13.1. The se sequences include four beta-glucuronidase sequences, two retrotrans poson sequences, a novel cDNA, a Sequence Tagged Site (STS), and one t hat is homologous to exon 9 of the Neuronal Apoptosis Inhibitor Protei n (NAIP) gene. The 6p21.3 paralogous SMA region may contain genes that are related to those in the SMA region at 5q13.1; however, a direct a ssociation of this region with SR;IA is unlikely given that no linkage of SMA with Chr 6 has been reported.