Insulin dependent diabetes mellitus epidemiology: HLA genotype study in 12 north eastern Italian families with two siblings affected by type I diabetes

Characteristics of Interferon-Associated Diabetes Mellitus in Past 30 Years: A Review

Interferon (IFN) is a broad-spectrum antiviral agent that activates cell surface receptors and causes cells to produce antiviral proteins, inhibiting viral replication. Interferon use has long been associated with diabetes. The PubMed database was searched for articles related to diabetes and interferon from March 30, 2020. Patients were divided into type 1 diabetes group and type 2 diabetes group. We reviewed the relevant literature to compare interferon-associated T1D and interferon-associated T2D differences. Interferon treatment shortened the incubation period of T2D and changed the original T2D to T1D. The onset of interferon-associated T1D required longer periods of IFN treatment than interferon-associated T2D, and the interferon-associated T1D group had higher GADA positive rates, lower BMI, lower fasting blood glucose, and greater insulin dependence (p<0.05). More patients in the T1D group were positive for HLA-DRB1*04, DRB1*03, DRB1*09, DRB1*14, HLA-DQB1*04, HLA-DQB1*02, HLA-DQB1*03, and HLA-DQB1*05. The combined detection of GAD antibodies and HLA alleles may be an effective method to predict the incidence of T1D after IFN treatment.

The distribution of HLA class II susceptible/protective haplotypes could partially explain the low incidence of type 1 diabetes in continental Italy (Lazio region)

HLA class II is the primary susceptibility gene to type 1 diabetes and the analysis of HLA class II association could help to clarify the relative weight of genetic contribution to the incidence of the disease. Here we present an extensive typing for HLA class II alleles and their haplotypes in a homogenous population of type 1 diabetic patients (n=134) and controls (n=128) and in simplex (n=100) and multiplex families (n=50) from continental Italy (Lazio region). Among the various haplotypes tested, the DRB1*0301-DQA1*0501-DQB1*0201 was the most frequent found in type 1 diabetic patients and was transmitted in 82% of affected siblings, whereas DRB1*0402-DQA1*0301-DQB1*0302 appeared to have the highest odds ratio (10.4), this haplotype was transmitted in 96.3% of affected siblings, followed by DRB1*0405-DQA1*0301-DQB1*0302, DRB1*0405-DQA1*0301-DQB1*0201, DRB1*0401-DQA1*0301-DQB1*0302 and DRB1*0404-DQA1*0301-DQB1*0302. The following haplotypes showed a significant decreased transmission to diabetic siblings: DRB1*0701-DQA1*0201-DQB1*0303, DR2-DQA1*01-DQB1*0602, DR5-DQA1*0501-DQB1*0301. We suggest that the HLA DR/DQ haplotype/genotype frequencies observed could in part explain the low incidence of type 1 diabetes registered in Lazio region (8.1/100.000/year), for a number of reasons: i) the low frequency, in the general control population, of the most susceptible haplotypes and genotype for type 1 diabetes DRB1*0301-DQA1*0501-DQB1*0201 (14%), and DR4-DQA1*0301-DQB1*0302 (9%) and DRB1*0301-DQA1*0501-DQB1*0201/DR4-DQA1*0301-DQB1*0302 (0.8%) compared to other countries characterised by high incidence rate of the disease, Sardinia and Finland, respectively; ii) a significant lower ratio, in the control population, between the susceptible DRB1*0301-DQA1*0501-DQB1*0201 and the neutral DRB1*0701-DQA1*0501-DQB1*0201 haplotypes compared to the Sardinian population; iii) the high frequency of protection haplotypes/genotypes as the DR5-DQA1*0501-DQB1*0301, and DR5-DQA1*0501-DQB1*0301/DR5-DQA1*0501-DQB1*0301 very common in the control population of Lazio region and the DRB1*1401-DQA1*0101-DQB1*0503 haplotype.

Inheritance of MHC class II genes in IDDM studied in population-based affected and control families

The transmission of HLA-DR and DQ was compared between 46 families with at least one child affected by insulin dependent diabetes mellitis (IDDM) and 43 healthy control families. In the patient families, there was an increased transmission of DR4 (p < 0.025) and DQB1*0302 (p < 0.01) from both parents to the index patient. There was an increased transmission of DQB1*0302 (p < 0.03) from the mothers only. The non-inherited maternal haplotypes showed a significantly decreased frequency (p < 0.01) of positively associated haplotypes (DR4-DQA1* 0301-DQB1*0302, DR3-DQA1*0501-DQB1*0201) compared to all parental haplotypes in the control families. In the control families neither transmission rates nor frequencies of non-inherited haplotypes differed from those expected in the control families. In conclusion, the observed reduction of IDDM-positively associated haplotypes in patient non-inherited maternal haplotypes, but not in non-inherited paternal haplotypes, suggests that tolerance during fetal life to maternal non-inherited HLA molecules may be important to diabetes development.