In sickness and in health: when myasthenia gravis is a conjugal matter

Abstract

Objective: Genes and environment contribute to the multifactorial etiology of autoimmune diseases. Familial clusters of autoimmune diseases are often observed among first-degree relatives sharing the same genetic background and environmental exposure. Rarer is the occurrence of the same autoimmune diseases in non-consanguineous spouses. We hereinafter report two non-consanguineous spouses who developed one after the other AChR-positive myasthenia gravis.

Methods: This study has been approved by Catholic University Ethic Committee. The wife, previously affected by Graves-Basedow disease, was the first to be diagnosed with myasthenia gravis, basing on a generalized weakness and an anti-AChR-positive assay. The husband, who suffered from ulcerative colitis, 16 years after his wife diagnosis complained of a mild generalized weakness. Repetitive nerve stimulation test and anti-AChR assay were confirmed myasthenia gravis. In these spouses, myasthenia gravis was not associated with thymoma. Human leukocyte antigen (HLA) class II genotyping showed distinct associations, with the wife carrying the DRB1*03:01 DQB1*02:01 and the husband the DRB1*07 DQB102 alleles.

Results: The wife's haplotype is strongly associated with myasthenia gravis and thyroiditis whereas HLA DRB1*07 allele was found to be related both to late-onset myasthenia gravis and ulcerative colitis.

Conclusions: Compared with other autoimmune disorders, myasthenia gravis has a lower prevalence. The surveillance environmental exposure may greatly improve our knowledge of non-genetic drivers of autoimmunity.

Keywords: Environment; Gene expression studies; HLA association; Myasthenia; Risk factors in epidemiology.