Myopathy with lactic acidosis is linked to chromosome 12q23.3-24.11 and caused by an intron mutation in the ISCU gene resulting in a splicing defect.

We describe the mapping and identification of the gene for hereditary myopathy with lactic acidosis (HML). HML is characterized by low physical performance, resulting in physical exertion that causes early exhaustion, dyspnoea and palpitations. Using an autosomal recessive mode of inheritance, we mapped the trait to chromosome 12q23.