Sasson Sarah C, Corbett Alastair, McLachlan Andrew J, Chen R, Adelstein S A, Riminton Sean, Limaye Sandhya
Nuffield Department of Medicine, Experimental Medicine Division, University of Oxford, Level 5, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
Department of Neurology, Concord Hospital, Sydney, Australia.
J Med Case Rep. 2019 Nov 20;13(1):338. doi: 10.1186/s13256-019-2285-3.
Myotonic dystrophy type 1 is an autosomal dominant disorder characterized by muscle weakness, myotonia, cataracts, and cardiac conduction defects; it is associated with expansions of cytosine-thymine-guanine repeats in the myotonic dystrophy protein kinase. Hypogammaglobulinemia is a lesser known association of myotonic dystrophy type 1 and the underlying pathogenesis of immunoglobulin G depletion remains unclear.
Here we report a kindred of two members (a 62-year-old white woman and a 30-year-old white man; mother and son) with myotonic dystrophy type 1-associated hypogammaglobulinemia associated with altered intravenous immunoglobulin elimination kinetics and reduced half-life. There was no history of systemic immunosuppression or renal or gastrointestinal protein loss in either patient, and no underlying case for a secondary immunodeficiency could be found. One patient required fortnightly intravenous immunoglobulin to maintain adequate trough immunoglobulin G levels.
Ongoing study of myotonic dystrophy type 1-associated hypogammaglobulinemia using contemporary tools of genomic medicine may help to further delineate the pathogenesis of this entity.
1型强直性肌营养不良是一种常染色体显性疾病，其特征为肌肉无力、肌强直、白内障和心脏传导缺陷；它与强直性肌营养不良蛋白激酶中胞嘧啶-胸腺嘧啶-鸟嘌呤重复序列的扩增有关。低丙种球蛋白血症是1型强直性肌营养不良鲜为人知的一种关联情况，而免疫球蛋白G缺乏的潜在发病机制仍不清楚。
在此，我们报告一个由两名成员（一名62岁白人女性和一名30岁白人男性；母亲和儿子）组成的家系，他们患有与1型强直性肌营养不良相关的低丙种球蛋白血症，伴有静脉注射免疫球蛋白清除动力学改变和半衰期缩短。两名患者均无全身免疫抑制病史，也无肾脏或胃肠道蛋白质丢失情况，且未发现继发性免疫缺陷的潜在病因。一名患者需要每两周静脉注射一次免疫球蛋白，以维持足够的免疫球蛋白G谷浓度水平。
使用当代基因组医学工具对1型强直性肌营养不良相关低丙种球蛋白血症进行持续研究，可能有助于进一步阐明该病症的发病机制。
