Objective:To summarize the characteristics of clinical, muscle pathology and gene mutation of late-onset reducing body myopathy caused by FHL1 gene mutation, in order to improve clinicians′ understanding of this disorder. Methods:The clinical, muscle pathology and muscle magnetic resonance imaging data of the proband from a family diagnosed as reducing body myopathy in Jiaozuo People′s Hospital in December 2021 were collected. Genetic tests and pedigree verification were conducted on the proband and her son.Results:The proband was a 59-year-old female with progressive, asymmetrical limb weakness and muscular atrophy. Her mother, sister and brother had similar symptoms. Electromyography showed myogenic and neurogenic damage. Muscle magnetic resonance imaging indicated that the lesion mainly involved the posterior muscles of the thigh and calf, as well as the gluteus maximus. The muscle pathology showed eosinophilic granular inclusion bodies and rimmed vacuoles in the muscle fibers of the lesion. The structure of myofibrils was disordered and abnormal protein deposition was observed. The gene sequencing showed the FHL1 gene p.C150S heterozygous variation. Conclusions:Late-onset reducing body myopathy is characterized by progressive asymmetric proximal limb muscle weakness, partially involving distal limb muscles and gluteus maximus. Muscle pathology shows the characteristic pathological changes of many kinds of myofibrillar myopathies. FHL1 gene mutation is an important basis for diagnosis.

Objective:To summarize the clinical, imaging, muscle pathological and gene mutational features of patients with late-onset mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS).Methods:Three patients with late-onset MELAS, admitted to Department of Neurology, Jiaozuo People's Hospital Affiliated of Xinxiang Medical University from January 1997 to December 2021 were chosen; all patients were screened for mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) mutations by second-generation gene sequencing. The clinical, imaging, muscle pathological and gene mutational features of patients with late-onset MELAS were analyzed retrospectively.Results:The main clinical manifestations of these late-onset MELAS patients included stroke-like attacks, headache, hearing and vision loss, cognitive decline and mental disorder. The muscle tension and muscle strength of both upper extremities in these 3 patients were normal. Increased muscle tension and active tendon reflexes, and positive pathological signs in both lower extremities were noted in 2 patients. Head MRI showed abnormal long T1 and long T2 signals in temporal occipital parietal cortex and subcortex in 3 patients, and CT showed calcification in bilateral globus pallidus in 1 patient. Ragged red fibers (RRF) and ragged blue fibers (RBF) were found in the muscle biopsies of 3 patients, and cytochrome oxidase (COX)-negative muscle fibers were found in 2 patients. MT-TL1 gene m.3243A>G mutation was detected in all 3 patients by genetic testing, among which mutation in the blood of 2 patients was 15% and 17%, respectively, and mutation in the muscle tissues of 1 patient was 73%. Conclusion:Muscle pathology indicates high RRF percentage in patients with late-onset MELAS; and m.3243A>G spot mutation is the most common mutation type in late-onset MELAS, and m.3243A>G mutation ratio in muscle tissues is obviously higher than that in blood.