Two single nucleotide polymorphisms identify the highest-risk diabetes HLA genotype: potential for rapid screening.

OBJECTIVE

People with the HLA genotype DRB10301-DQA10501-DQB10201/DRB104-DQA10301-DQB10302 (DR3/4-DQ8) are at the highest risk of developing type 1 diabetes. We sought to find an inexpensive, rapid test to identify DR3/4-DQ8 subjects using two single nucleotide polymorphisms (SNPs).

RESEARCH DESIGN AND METHODS

SNPs rs2040410 and rs7454108 were associated with DR3-DQB10201 and DR4-DQB10302. We correlated these SNPs with HLA genotypes and with publicly available data on 5,019 subjects from the Type 1 Diabetes Genetic Consortium (T1DGC). Additionally, we analyzed these SNPs in samples from 143 HLA-typed children who participated in the Diabetes Autoimmunity Study of the Young (DAISY) using Taqman probes (rs7454108) and restriction digest analysis (rs2040410).

RESULTS

With a simple combinatorial rule, the SNPs of interest identified the presence or absence of the DR3/4-DQ8 genotype. A wide variety of genotypes were tested for both SNPs. In T1DGC samples, the two SNPs were 98.5% (1,173 of 1,191) sensitive and 99.7% (3,815 of 3,828) specific for DR3/4-DQ8. In the DAISY population, the test was 100% (69 of 69) sensitive and 100% (74 of 74) specific. Overall, the sensitivity and specificity for the test were 98.57 and 99.67%, respectively.

CONCLUSIONS

A two-SNP screening test can identify the highest risk heterozygous genotype for type 1 diabetes in a time- and cost-effective manner.