AFFECTED-SIB-PAIR MAPPING OF A NOVEL SUSCEPTIBILITY GENE TO INSULIN-DEPENDENT DIABETES-MELLITUS (IDDM8) ON CHROMOSOME 6Q25-Q27

Affected-sib-pair analyses were performed using 104 Caucasian families to map genes that predispose to insulin-dependent diabetes mellitus ( IDDM). We have obtained linkage evidence for D6S446 (maximum lod score [MLS] = 2.8) and for D6S264 (MLS = 2.0) on 6q25-q27. Together with a previously reported data set, linkage can be firmly established (MLS = 3.4 for D6S264), and the disease locus has been designated IDDM8. Wit h analysis of independent families, we confirmed linkage evidence for the previously identified IDDM3 (15q) and DDM7 (2q). We also typed add itional markers in the regions containing IDDM3, IDDM4, IDDM5, and IDD M8. Preliminary linkage evidence for a novel region on chromosome 4q ( D4S1566) has been found in 47 Florida families (P < .03). We also foun d evidence of linkage for two regions previously identified as potenti al linkages in the Florida subset: D3S1303 on 3q (P < .04) and D7S486 on 7q (P < .03). We could not confirm linkage with eight other regions (D1S191, D1S412, D4S1604, D8S264, D8S556, D10S193, D13S158, and D18S6 4) previously identified as potential linkages.