Is the high incidence of diabetes in young children diagnosed under the age of 4 years determined by genetic factors in Finland? The DIME Study Group.
The incidence of Type 1 diabetes among 1- to 4-year-old children in Finland is very high (31/100,000). The aim of our study was to find out if there is a genetic reason for this high incidence of diabetes in young children. The study subjects came from a population-based Finnish Type 1 diabetes study (DiMe Study) where 169 children were diagnosed under the age of 4 years, and 566 between 5 and 14 years.


RESULTS
The frequencies of most HLA haplotypes which confer susceptibility to Type 1 diabetes including the two most common haplotypes in middle and Northern European populations the A2, Cw3, B62, DR4, DQ8 and the A1, Cw7, B8, DR3, DQ2 haplotypes were similar in the two age groups (0-4 years versus 5-14 years). In contrast, the A2, Cw1, B56, DR4, DQ8 susceptibility haplotype, which has so far only been found in Type 1 diabetes in Finland, was more frequent in the younger age group (8.3% versus 4.7%, p < 0.009). Also the A3, Cw4, B35, DR4, DQ8 haplotype was more frequent in the younger age group (4.1% versus 1.9%, p < 0.014). The frequency of DR3, DR4 heterozygosity did not differ significantly between the age groups (26.6% versus 20.0%).


CONCLUSIONS
The early peak in Type 1 diabetes is partially explained by HLA genetic factors. Two specific HLA haplotypes may explain about 25% of cases diagnosed under the age of 5 years.
Tuomilehto-Wolf
E
E
Department of Epidemiology and Health Promotion, National Public Health Institute, Helsinki, Finland.
Tuomilehto
J
J
D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology* / Q000235:genetics* / Q000276:immunology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006680:HLA Antigens / Q000097:blood; D006684:HLA-DR Antigens / Q000097:blood; D006239:Haplotypes; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012042:Registries; D012737:Sex Factors
D006680:HLA Antigens; D006684:HLA-DR Antigens