The goal of this proposal is to clarify the relationship between DNA polymorphism and specific haplotypes on chromosome 6 and 11 with the aim of detecting more specific markers that predispose to insulin-dependent diabetes (IDDM). Family studies indicate that the HLA region is associated with IDDM. However, the specific genes within this region which provide this susceptibility are not clearly delineated. Furthermore, the HLA region cannot by itself define the total genetic contribution to IDDM. The best candidate for a second contributing genetic component to IDDM exists on chromosome 11. We propose to better define the HLA and chromosome 11 genetic components in IDDm by using recombinant DNA technology to study gene polymorphisms for various loci in families containing IDDM members. DNA from lymphoblastoid lines of 65 Caucasian families with about 400 members completely typed for HLA antigens, A, B, C, and DR, complement BF, C2 and C4 alleles and glyoxylase I alleles will be typed using cDNA and genomic DNA probes for HLA-DQ, DR, and DR alpha and beta DNA sequences. In addition, probes of higher specificity (Oligonucleotides of 19-33 residues) will be generated. To determine the oligonucleotide probe sequences, DNA from various individuals homozygous for """"""""extended haplotypes"""""""" associated with IDDM will be used to prepare chromosomal gene """"""""libraries."""""""" HLA genes will be isolated and characterized from these individuals. Furthermore, new genes 5' and 3' to the isolated genes will be obtained by """"""""chromosome walking."""""""" The DNA polymorphism detected using cDNA, genomic and oligonucleotide probes will be compared with the HLA haplotypes determined by conventional methods. Families will also be typed for chromosome 11 polymorphic DNA markers spanning a large region of chromosome 11 and haplotypes determined. Non-diabetic sibs to a diabetic proband in each family will be scored as sharing 2, 1 or 0 chromosome 11 haplotypes. The distribution of these haplotypes will be compared to those expected if no chromosome 11 association was included (25% 2 haplotypes shared, 50% 1 haplotype shared and 25% O haplotypes shared). The ultimate goal of this study is to provide a better understanding of the genes that predispose to IDDM. It is hoped that the increased sensitivity of the DNA methodologies described will contribute new insights into the etiological, diagnostic and preventative aspect of IDDM.
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