The less frequent genotype of AICDA in IgAD patients was AA, seen in 10.5% of the patients, which was much lower than the 30.8% in CVID patients and 38.2% in the controls.
The aim of this study was to investigate whether autoantibodies against BAFF (important B cell survival signal), APRIL (important plasma cell survival signal), or Interleukin-21 (important cytokine for immunoglobulin class switch) present an alternative mechanism for the development of the following primary antibody deficiencies (PADs): common variable immune deficiency (CVID) or selective IgA deficiency (sIgAD).
Moreover, spontaneous apoptosis of CD19(+) B cells from patients with CVID or IgAD was prevented by a combination of IL-21, IL-4, and anti-CD40 stimulation.
We show that a combination of IL-21, IL-4, and anti-CD40 stimulation induces class-switch recombination to IgG and IgA and differentiation of Ig-secreting cells, consisting of both surface IgG(+) (sIgG(+)) and sIgA(+) B cells and CD138(+) plasma cells, in patients with CVID or IgAD.
There are strong indications for involvement of genetic factors in development of the disease and the frequency of several extended major histocompatibility complex haplotypes (including HLA-A1, B8, DR3, DQ2) have previously been shown to be increased among Caucasian patients with IgAD.PCR was used to type HLA B, DR, and DQ alleles in 29 Iranian individuals with IgAD and 299 Swedish individuals with IgAD.The results indicate a strong association with the HLA B14, DR1 alleles in Iranian subjects and HLA B8, B12, B13, B14, B40, DR1, DR3, DR7, DQ2 and DQ5 alleles in Swedish subjects.Differences in HLA association of IgAD in Iran and Sweden confirm the notion of a genetic background of the disease and that multiple, potentially different genes within the MHC region might be involved in the pathogenesis of IgAD in different ethnic groups.
Recent studies in patients with late-onset hypogammaglobulinaemia and selective IgA deficiency showed that there may be a common denominator for these two syndromes, since there is a close association with polymorphic antigens of the MHC class III region.
An extended statistical analysis strengthened the hypothesis that selective IgA deficiency might be communicated by the distinct haplotype DRB1*0301, DQB1*02.
We aimed at evaluating the role of those MSH5 polymorphisms on IgAD susceptibility considering their linkage with other classically associated HLA markers, specifically DRB1*0102 and B*08-DRB1*03.
Our genome-wide association study (GWAS) meta-analysis of 1,635 patients with IgAD and 4,852 controls identified four new significant (P < 5 × 10<sup>-8</sup>) loci and association with a rare IFIH1 variant (p.Ile923Val).