In a collaborative effort by 12 centers from Europe and North America, data were assembled from 94 multiplex families with insulin-dependent diabetes mellitus (IDDM) for analysis of genetic and other factors of possible etiological importance. The dataset contains information on the following genetic markers: HLA-DR beta and -DQ beta restriction fragment length polymorphisms (RFLPs), three RFLPs detected with two probes that map 5' to the insulin gene, the serologically defined HLA loci, and the immunoglobulin allotypes. Data also were included for auto-antibodies to insulin and pancreatic islet cells as possible indicators of pathogenesis and for antibodies to certain viruses that have been implicated as "triggering" agents in IDDM. Medical history of family members was obtained by means of a uniform questionnaire. Identical copies of the dataset were distributed to anyone wishing to participate in the analysis for the IDDM component of GAW5. The multiplex IDDM family dataset is now available on request for further analysis.

The primary aim of the insulin‐dependent diabetes mellitus (IDDM) component of Genetic Analysis Workshop 5 (GAW5) was to collect and analyze new data on DNA polymorphisms closely linked to the HLA‐D region and the insulin gene. The probes and restriction enzymes described here were used by all ten participating labs, and the data from Southern blotting were interpreted and reported according to conventions developed for the Workshop. These DNA data on members of 94 families with two or more IDDM sibs constitute the largest such sample available. The data were used in most of the analyses presented at the Workshop meeting, and are available on request.