Distribution of subtypes of the BF system in type 1 (insulin-dependent) and type 2 (non-insulin dependent) diabetes mellitus.

In this study 148 type 1 diabetic patients (mean age: 33 years) and 100 type 2 diabetic patients (mean age: 57.3 years) were typed for BF subtypes by means of isoelectrofocusing in polyacrylamide gel (pH range 5.0-8.0) according to Geserick. The frequencies of BF subtypes and the distribution patterns were compared with 584 blood donors. In type 1 diabetics the distribution pattern of BF phenotype frequencies differs significantly from the data of type 2 diabetics and controls. The difference is mainly due to the frequent occurrence of the rare alleles BFF1 and BFSO7. The frequency of the two alleles amounted to 0.0338 and 0.0270, respectively. The relative risk of carriers of the rare alleles BFF1 and BFSO7 was 5.3 and 6.6, respectively. The study demonstrates a marked association between the early onset of type 1 diabetes (less than 20 years of age) and the BFF1 allele. There is no relationship between the rare variants of alleles of the BF system and the occurrence of proliferative retinopathy. However, there was no association between the rare variants of alleles of the BF system and type 2 diabetes mellitus. In summary, the study add further support for genetic heterogeneity of the BF system in type 1 diabetes mellitus.