CDNA ISOLATION, EXPRESSION, AND CHROMOSOMAL LOCALIZATION OF THE MOUSESURVIVAL MOTOR-NEURON GENE (SMN)

Spinal muscular atrophy (SMA) is a frequent autosomal recessive diseas e in human characterized by degeneration of motor neurons of the spina l cord. The genomic region containing the defective gene (5q13) is par ticularly unstable and prone to large-scale deletions whose characteri zation led to the identification of the survival motor neuron (SMN) ge ne, the SMA determining gene encoding a hitherto unknown protein. As a n initial step toward the generation of a murine model for SMA, we ide ntified and characterized a full-length murine Smn cDNA. The coding se quence of the mouse Smn gene was found to be 82% identical, at the ami no acid level, with the human SMN coding sequence. The Smn locus was m apped to the segment of mouse chromosome 13 exhibiting conservation of synteny with human chromosome 5q11-q23, which contains the SMN gene. However, no evidence for a duplication of the Smn gene was found in th e mouse, suggesting that the duplication reported in human is a recent evolutionary event. (C) 1997 Academic Press.