MOLECULAR MAPPING OF 21 FEATURES ASSOCIATED WITH PARTIAL MONOSOMY-21 - INVOLVEMENT OF THE APP-SOD1 REGION

We compared the phenotypes, karyotypes, and molecular data for six cas es of partial monosomy 21. Regions of chromosome 21, the deletion of w hich corresponds to particular features of monosomy 21, were thereby d efined. Five such regions were identified for 21 features. Ten of the features could be assigned to the region flanked by genes APP and SOD1 : six facial features, transverse palmar crease, arthrogryposis-like s ymptoms, hypertonia, and contribution to mental retardation. This regi on, covering the interface of bands 21q21-21q22.1, is 4.7-6.4 Mb long and contains the gene encoding the glutamate receptor subunit GluR5 (G RIK1).