HOMOLOGOUS RECOMBINATION OF A FLANKING REPEAT GENE-CLUSTER IS A MECHANISM FOR A COMMON CONTIGUOUS GENE DELETION SYNDROME

Smith-Magenis syndrome (SMS), caused by del(17)p11.2, represents one o f the most frequently observed human microdeletion syndromes. We have identified three copies of a low-copy-number repeat (SMS-REPs) located within and flanking the SMS common deletion region and show that SMS- REP represents a repeated gene cluster. We have isolated a correspondi ng cDNA clone that identifies a novel junction fragment from 29 unrela ted SMS patients and a different-sized junction fragment from a patien t with dup(17)p11.2. Our results suggest that homologous recombination of a flanking repeat gene cluster is a mechanism for this common micr odeletion syndrome.