The MELAS phenotype may not only be determined by heteroplasmy of causative mtDNA variants

摘要

I read with interest, the article by Chae et al. about a study of 32 paediatric patients with MELAS of whom 25 underwent next-generation sequencing (NGS) (1). It was concluded that heteroplasmy rates correlated inversely with age at onset and age at diagnosis (1). This raises the following comments and concerns.The main shortcoming of the study is that heteroplasmy rates were determined in blood lymphocytes, which are usually not severely affected in MELAS. Thus, heteroplasmy rates in blood lymphocytes may not represent heteroplasmy rates in other more severely affected tissues. This is why the results provided remain questionable. Heteroplasmy rates should also be determined in tissue such as buccal mucosa cells, hair follicles, urine epithelial cells, skin fibroblasts, or the skeletal muscle.