The HLA-DRB1 gene and Graves disease in Taiwanese children: a case-control and family-based study

HLA Class II Allele Groups Involved in Autoimmune Thyroid Diseases: Hashimoto's Thyroiditis and Basedow-Graves Disease

Autoimmune thyroid diseases (AITD), particularly Hashimoto's thyroiditis (HT) and Basedow-Graves disease (BGD) are diseases of global public health concern, characterized by autoimmune attacks on the thyroid gland, leading to hypothyroidism in HT and hyperthyroidism in BGD. We conducted a study between 2019 and 2021 in northwestern Transylvania (Romania) on patients with HT and with BGD compared to the control group. The aim of the study was to investigate the correlations of HLA class II alleles with AITD by identifying potential genetic susceptibility factors such as HLA-DRB1 and HLA-DQB1 genes in patients diagnosed with HT and BGD. Various molecular biology methods, including SSP-PCR low-resolution and PCR-SSO were employed to analyze DNA samples from patients and control subjects. Our study revealed the influence of the HLA-DRB1*03/*16 genotype as a genetic susceptibility factor for HT, a similar influence regarding BGD being observed for the HLA-DRB1*03 allele group, DRB1*03/*16 genotype, and the DRB1*03/DQB1*06 haplotype. The only protective factor detected in our study was the HLA-DRB1*13 allele group, for both HT and BGD. By elucidating any specific allele or genotype associations that might contribute to the development of AITD, our study can contribute to the prevention and early detection of these diseases.

Genotype-phenotype correlations in Graves' disease

Graves' disease (GD) is a heterogeneous autoimmune disease affecting with varying degrees of severity the thyroid gland, orbital tissues and skin. The pathogenesis of GD involves a complex interplay between multiple genetic, environmental and endogenous factors. Although the genetic predisposition to GD is well established, the significance of genotype-phenotype correlations and the role of epigenetic modifications in the disease pathogenesis remains largely unknown. In this review, we provide an up-to-date overview of genotype-phenotype correlations and summarize possible clinical implications of genetic and epigenetic markers in GD patients. We will specifically discuss the association of genetic markers and epigenetic modifications with age of GD onset, severity of Graves' hyperthyroidism and the development of clinically evident Graves' orbitopathy.

Critical amino acid variants in HLA-DRB1 allotypes in the development of Graves' disease and Hashimoto's thyroiditis in the Japanese population

The effects of amino acid variants encoded by human leukocyte antigen (HLA) class II on the development of Graves' disease (GD) and Hashimoto's thyroiditis (HT) have not been fully elucidated. We investigated the HLA-DRB1 genes of 243 GD patients and 82 HT patients in the Japanese population and compared the frequencies of HLA-DRB1 alleles and HLA-DRB1 amino acid variants between these patients and the Japanese populations previously reported by another institution. The frequencies of HLA-DRB1*04:05 and -DRB1*14:03 alleles were significantly higher and those of HLA-DRB1*01:01 and -DRB1*15:02 alleles were lower in GD patients than in controls. The frequencies of HLA-DRB1*08:03 and -DRB1*09:01 alleles were significantly higher and that of the HLA-DRB1*13:02 allele was lower in HT patients than in controls. A blind association analysis with all amino acid positions identified DRß9 and DRß31 for GD and DRß9, DRß13, and DRß21 for HT. The frequency of Glu-9 was significantly higher and that of Cys-9 was lower in GD patients than in controls. The frequencies of Lys-9 and Phe-13 were significantly higher in HT patients than in controls. DRß9 and DRß13 could be critical amino acid positions in the development of GD and HT.

Paediatric-onset and adult-onset Graves' disease share multiple genetic risk factors

BACKGROUND

Graves' disease (GD) is an autoimmune thyroid disease (AITD) with a peak incidence between 30 and 50 years of age. Although children and adolescents may also develop the disease, the genetic background of paediatric-onset GD (POGD) remains largely unknown. Here, we looked for similarities and differences in the genetic risk factors for POGD and adult-onset GD (AOGD) as well as for variants associated with age of GD onset.

MATERIALS AND METHODS

A total of 1267 GD patients and 1054 healthy controls were included in the study. Allele frequencies of 40 established and suggested GD/AITD genetic risk variants (39 SNPs and HLA-DRB1*03) were compared between POGD (N = 179), AOGD (N = 1088) and healthy controls. Subsequently, multiple linear regression was used to explore the relationship between age of GD onset and genotype for each locus.

RESULTS

We identified six POGD risk loci, all of them were also strongly associated with AOGD. Although for some of the analysed variants, including HCP5 (rs3094228), PRICKLE1 (rs4768412) and SCGB3A2 (rs1368408), allele frequencies differed nominally between POGD and AOGD patients, these differences were not significant after applying multiple testing correction (P_cor  = 0.05/40 = 1.25 × 10^-3 ). Regression analysis showed that patients with higher number of HCP5 risk alleles tend to have a significantly earlier onset of GD (P = 6.9 × 10^-5 ).

CONCLUSIONS

The results of our study revealed that POGD and AOGD share multiple common genetic risk variants. Moreover, we demonstrated for the first time that HCP5 polymorphism is associated with an earlier age of GD onset in a dose-dependent manner.

Late-Onset Disseminated Mycobacterium avium intracellulare Complex Infection (MAC), Cerebral Toxoplasmosis and Salmonella Sepsis in a German Caucasian Patient with Unusual Anti-Interferon-Gamma IgG1 Autoantibodies

PURPOSE

Since we described for the first time a patient with IgG4 autoantibodies to IFN-γ more than 10 years ago, many patients with IFN-γ IgG4 autoantibodies have been described, mostly in Mongolian/ Asian patients with a particular HLA background and in association with disseminated nontuberculous mycobacterial infections. Very recently, the first Caucasian US patient was reported and we now present the case of a 65-year old Caucasian woman with severe disseminated Mycobacterium avium infection, cerebral toxoplasmosis and salmonella sepsis who was tested positive for IFN-γ deficiency due to unusual anti-IFN-γ IgG1 autoantibodies.

METHODS

IFN-γ production after ex vivo ConA stimulation of the patient's whole blood and isolated peripheral blood mononuclear cells was assessed. Anti-human IFN-γ antibodies were measured by Ig/Ig-subclass-specific ELISA. In vitro physiologic relevance and blocking capacity of IFN-γ-stimulation by patient's serum was analysed by flow cytometric assessment of cytokine-induced phosphorylation of pSTAT1(Y701).

RESULTS

Severely impaired IFN-γ production in the patient's whole blood but normal production in peripheral blood mononuclear cells in the absence of autologous serum was observed. High titre anti-IFN-γ antibodies of the IgG1 subclass could be demonstrated in the patient's serum by ELISA. Further, the addition of patient's serum to IFN-γ-stimulated immune cells showed inhibition of STAT1 phosphorylation.

CONCLUSIONS

IFN-γ autoantibodies of any IgG-isotype should be considered in patients with severe opportunistic infections independent of age at onset and ethnicity.