Background: A genome-wide search for genes that predispose to type 1 diabetes using linkage analysis was performed using 900 microsatellite markers in 70 nuclear families with affected siblings from Finland, a population expected to be more genetically homogeneous than others, and having the highest incidence of type 1 diabetes in the world and, yet, the highest proportion in Europe of cases (10%) carrying neither of the highest risk HLA haplotypes that include DR3 or DR4 alleles.
Results: In addition to the evidence of linkage to the HLA region on 6p21 (nominal p = 4.0 x 10-6), significant evidence of linkage in other chromosome regions was not detected with a single-locus analysis. The two-locus analysis conditional on the HLA gave a maximum lod score (MLS) of 3.1 (nominal p = 2 x 10-4) on chromosome 9p13 under an additive model; MLS of 2.1 (nominal p = 6.1 x 10-3) on chromosome 17p12 and MLS of 2.5 (nominal p = 2.9 x 10-3) on chromosome 18p11 under a general model.
Conclusion: Our genome scan data confirmed the primary contribution of the HLA genes also in the high-risk Finnish population, and suggest that non-HLA genes also contribute to the familial clustering of type 1 diabetes in Finland.