16 Aug 2001

Spinal muscular atrophy with respiratory distress type 1 (SMARD1), a life-threatening disease that strikes infants as young as four weeks, is due to loss of neurons in the anterior horn of the spinal cord. The exact cause of this neural blight is unknown, but the ensuing muscular atrophy can lead to paralysis of the diaphragm and respiratory failure. Led by Christoph Hübner at the Humboldt University, Berlin, scientists from Europe, Canada, and Australia have now mapped the gene for human SMARD1, previously linked to the long arm of chromosome 11, to within a DNA region of nine cM in length. The study, which appears in the September Nature Genetics, shows that the most likely cause of SMARD1 among six unrelated families is mutation of the gene for immunoglobulin m-binding protein 2 (IGHMBP2). Though mutations in IGHMBP2 have been shown to cause severe deformities in mice, the precise function of the protein is still unknown. It may be involved in RNA processing or regulation of transcription as it contains several motifs, including a DEAD box-like motif found in RNA helicases.—Tom Fagan