PROGRESS IN THE AUTOSOMAL SEGMENTAL ANEUSOMY SYNDROMES (SASS) - SINGLE OR MULTILOCUS DISORDERS

Based on cytogenetic observations, several syndromes have been previou sly identified as microdeletion-based disorders, In this review, recen t progress is presented regarding whether one or multiple genes can be implicated in the pathogenesis of these segmentally aneusomic syndrom es, The syndromes discussed include Angelman, Alagille, Williams, Lang er-Giedeon, Prader-Willi, Smith-Magenis, Miller-Dieker, and DiGeorge/v elocardiofacial or the 22q11 deletion syndromes. For Angelman and Alag ille syndromes, single genes have been identified, whereas for William s and Langer-Giedion syndromes, more than one gene can be implicated. Although there has been significant progress in dissecting the molecul ar basis for the other disorders, the ultimate answer regarding one ve rsus several genes remains to be determined.