What is the molecular analysis of B-cell differentiation in patients with immunoglobulin A deficiency (IgAD)?

Updated: May 15, 2018
  • Author: Marina Y Dolina, MD; Chief Editor: Michael A Kaliner, MD  more...
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Answer

Molecular analyses of B-cell differentiation in a small number of patients with selective or partial IgAD suggest that decreased expression level of alpha germline transcripts before a class switch might be critical for the pathogenesis of some patients with SIgAD. A case report from Japan described using reverse transcription polymerase chain reaction (RT-PCR) to separately evaluate alpha1 and alpha2 mRNAs and described a second case of alpha1 gene deletion, which manifested as a partial IgAD. [17] Another possible explanation is allelic variation in the heavy chain 3" regulatory region. A group in Canada evaluated HS1.2 allelic frequencies in 88 SIgAD patients and 101 controls, demonstrating a 39% homozygosity of the allele *1 in patients and 15% homozygosity in controls. [18]

In patients with a partial IgA deficiency, B-cell differentiation might be disturbed after a class switch. [19] The TACI receptor and 2 ligands (BAFF and APRIL) likely play a role in the pathogenesis of defective humoral immunity. BAFF is B-cell activating factor, and APRIL is a proliferation-inducing ligand. TACI is a tumor necrosis receptor superfamily member that is involved in lymphocyte maturation and survival. In mice, deletion of the sequences coding for TACI or BAFF (B-lymphocytestimulator [BLyS]) interfere with B-cell class switching and result in IgA deficiency.


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