Background Serum IgA and IgM levels in cohorts of adults with hemochromatosis are not reported.

Methods We compiled serum IgA and IgM levels at diagnosis of hemochromatosis in probands with HFE p.C282Y (rs1800562) homozygosity, investigated associations of IgA and IgM with clinical and other laboratory characteristics, and compared mean IgA and IgM of probands with combined/weighted means of published adult European cohorts not selected for hemochromatosis.

Results There were 73 probands (36 men, 37 women; mean age 51 ± 13 y). Fifty probands (68.5%) had human leukocyte antigen (HLA)-A*03. Mean IgA ± standard deviation [95% confidence interval] was 2.11 ± 1.06 g/L [1.87, 2.35]. Mean IgM was 1.11 ± 0.75 g/L [0.94, 1.28]. IgM was inversely associated with age (Pearson’s r73 = –0.2733; p = 0.019). A multiple regression on IgA revealed no significant association with other characteristics. A regression on IgM revealed one positive association (daily alcohol intake; p = 0.036) and one negative association (age; p = 0.016). Mean IgA of male and female probands and corresponding mean IgA of Europeans in two cohorts (918 men, 458 women) did not differ significantly. Mean IgM of probands was lower than the mean IgM of Europeans in four cohorts (men 1.03 ± 0.84 g/L vs. 1.35 ± 0.55 g/L (n = 1084)), respectively (p <0.001); women 1.18 ± 0.67 g/L vs. 1.57 ± 0.68 g/L (n = 622), respectively (p <0.001)).

Conclusions Serum IgM levels of hemochromatosis probands with HFE p.C282Y homozygosity are positively associated with daily alcohol intake and inversely associated with age. Mean IgM levels of male and female probands are lower than those of European men and women not selected for hemochromatosis.

The authors have declared no competing interest.

This study did not receive any funding.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

This retrospective work was performed according to the principles of the Declaration of Helsinki [15]. The performance of this study was approved by the Western Institutional Review Board, Inc. (submission 2539985-44189619). Western Institutional Review Board, Inc. waived the need for obtaining informed consent from participants in this study under the United States Department of Health and Human Services, Office for Human Research Participants, regulation 45 CFR 46.101(b)(4). Informed consent was not required and thus was not obtained because this study involved retrospective chart reviews and analyses of observations recorded in routine medical care. Data analyzed in this study were not anonymized before the investigators accessed them because data were compiled from proband charts in an Alabama tertiary hematology center wherein JaCB and LFB diagnosed and treated all probands, consistent with Western Institutional Review Board, Inc. approval of this study. JaCB, JClB, and LFB had access to information that could identify individual probands during and after data collection. Data were compiled and analyzed during the interval 30 December 2018 - 3 June 2020. All data in this report are displayed in a manner that maintains proband anonymity in both the present results and the corresponding dataset [16].

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