Diagnostic challenges in metabolic myopathies

Introduction: Metabolic myopathies comprise a clinically etiological diverse group of disorders caused by defects in cellular energy metabolism including the breakdown of carbohydrates and fatty acids, which include glycogen storage diseases and fatty acid oxidation disorders. Their wide clinical spectrum ranges from infantile severe multisystemic disorders to adult-onset myopathies. To suspect in adults these disorders, clinical features such as exercise intolerance and recurrent myoglobinuria need investigation while another group presents fixed weakness and cardiomyopathy as a clinical pattern.

Areas covered: In metabolic myopathies, clinical manifestations are important to guide diagnostic tests used in order to lead to the correct diagnosis. The authors searched in literature the most recent techniques developed. The authors present an overview of the most common phenotypes of Pompe disease and what is currently known about the mechanism of ERT treatment. The most common disorders of lipid metabolism are overviewed, with their possible dietary or supplementary treatments.

Expert opinion: The clinical suspicion is the clue to conduct in depth investigations in suspected cases of metabolic myopathies that lead to the final diagnosis with biochemical molecular studies and often nowadays by the use of Next Generation Sequencing (NGS) to determine gene mutations.

Keywords: Pompe disease; biomarkers; carnitine; fatty acid oxidation; glycogenosis type 2; glycogenosis type 5; newborn screening; riboflavin.