Laing early-onset distal myopathy with subsarcolemmal hyaline bodies caused by a novel variant in the MYH7 gene

Luís Negrão 1, Rita Machado 1, Miguel Lourenço 2, Ana Fernandez-Marmiesse 3,4, Olinda Rebelo 1

1 Neuromuscular Disease Unit, Neurology Department, Coimbra University and Hospital Centre, Coimbra, Portugal; 2 Neurology Department, Hospital de Santo Espírito da Ilha Terceira, Angra do Heroísmo, Portugal; 3 Unit for the Diagnosis and Treatment of Congenital Metabolic Diseases, Clinical University Hospital of Santiago de Compostela, Health Research Institute of Santiago de Compostela, Santiago de Compostela, Spain; 4 Genomes & Disease Group, Molecular Medicine and Chronic Diseases Research Centre (CiMUS), Santiago de Compostela University – IDIS, Santiago de Compostela, Spain

Myopathies caused by MYH7 gene mutations are clinically and pathologically heterogeneous and, until recently, difficult to diagnose. The availability of NGS panels for hereditary neuromuscular diseases changed our insight regarding their frequency and allowed a better perception of the different phenotypes and morphological abnormalities associated. 

We present a male Portuguese patient with the classical phenotype of Laing early-onset distal myopathy (MPD1) beginning at 6 years of age, very slowly progressive, and with a mild to moderate impact on daily life by the age of 56. Muscle biopsy showed a myopathic pattern with hyaline bodies and cores. The NGS panel for structural myopathies identified a novel missense heterozygous variant, c.T4652C (p.Leu1551Pro), in the exon 34 of the MYH7 gene.

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