Genetics of type 1 diabetes

Area of Science:

• Immunogenetics
• Endocrinology
• Pediatrics

Background:

• Type 1 diabetes (T1D) is an autoimmune disease targeting pancreatic beta cells, with a strong genetic basis.
• The Human Leukocyte Antigen (HLA) class II genes at 6p21 are major T1D susceptibility loci, accounting for 30-50% of genetic risk.
• Numerous non-HLA loci, including INS, PTPN22, and CTLA4, also contribute smaller effects to T1D risk.

Purpose of the Study:

• To identify children at extreme genetic risk for developing type 1 diabetes.
• To stratify genetic risk based on HLA genotypes and family history for T1D prevention trials.

Main Methods:

• Genomewide association studies (GWAS) using high-density single-nucleotide polymorphism (SNP) genotyping.
• Analysis of HLA class II genotypes (e.g., DR3/4-DQ8, DR4/DR4) in relation to islet autoimmunity.
• Assessment of family history of type 1 diabetes as a risk stratification factor.

Main Results:

• Children with HLA-risk genotypes (DR3/4-DQ8 or DR4/DR4) and a family history of T1D have >1 in 5 risk of childhood islet autoantibodies.
• Children with the same HLA-risk genotypes but no family history have approximately a 1 in 20 risk.
• Genetic risk can be further refined by considering other diabetes susceptibility genes and HLA identity.

Conclusions:

• Extreme genetic risk determination is essential for initiating primary prevention trials in relatives of T1D individuals.
• Early identification of high-risk children enables targeted interventions and monitoring.
• Understanding the interplay of HLA and non-HLA genes is key to T1D pathogenesis and prevention.