DELETION STATUS AND INTELLECTUAL IMPAIRMENT IN DUCHENNE MUSCULAR-DYSTROPHY

The authors collected Verbal, Performance and Full-scale IQs for 74 pa tients in whom complete analysis of the dystrophin gene for deletions and duplications had been performed. There was a significant differenc e in the mean Full-scale IQ between patients with deletions at the 5' and 3' ends of the gene, with no patients with 5' deletions having men tal retardation. No relationship was established between mental retard ation and the presence or absence of deletions or length of deletions, and similar deletions were observed in the presence and absence of me ntal retardation. Although distal deletions were more commonly associa ted with mental retardation, there was no clear evidence for a particu lar region of the dystrophin gene being specifically responsible for I Q. The intellectual deficit seen in DMD may be a consequence of cerebr al hypoxia, due to malfunction of smooth muscle dystrophin.