Myotonic dystrophy type 2 (MD2) is an autosomal dominant disorder characterized by myotonia and dystrophic muscle degeneration. Although it has been associated with hypogammaglobulinemia, it is not normally accompanied by clinically significant immunodeficiency.
We describe a case of fatal MD2 in an adult, who first presented with immune dysregulation, and who succumbed to rapid worsening of both conditions. We discuss relevant data, and review the literature of the muscular dystrophies and immunodeficiency.
The patient was referred to our clinic at the age of 34 for recurrent pneumonia since age 16, and an IgA deficiency. His immunodeficiency workup revealed low to absent immunoglobulins with essentially no specific antibodies, and low lymphocyte counts. Additional conditions included Type 1 diabetes, multiple other autoimmune disorders, granulomas of the skin and lungs, and subsequent opportunistic infections. He did not have thymoma. He then developed proximal muscle wasting and concomitant weight loss, and genetic testing revealed a characteristic MD2 genetic profile. Whole exome sequencing did not reveal a mutation in the Autoimmune Regulator (AIRE) gene, or any other significant mutations identified with primary immunodeficiency. The patient died due to complications of both MD2 and multiple infections.
While there have been reported associations of hypogammaglobulinemia with the muscular dystrophies, (perhaps due to increased catabolism of immunoglobulins), and decreased post-vaccination antibodies (particularly with MD1), we believe this is the first case of severe immunodeficiency associated with MD2. We hope to further examine a potential link between these conditions with a more targeted genomic analysis.