Myh2 encodes MyHCIIa, a myosin heavy chain found in fast type 2A fibers. It plays a crucial role in muscle function and is involved in muscle-related biological processes. Genetic models, such as gene knockout (KO) or conditional knockout (CKO) mouse models, can be valuable for studying its functions [1,3,4].

Pathogenic variants in MYH2 have been implicated in various myopathies. In an autosomal-dominant inheritance pattern, a novel splice-site variant MYH2 c.5673 + 1G>C was detected in a family with a slowly progressive, predominantly proximal myopathy, and this variant affects splicing, resulting in novel transcripts [1]. MYH2 myopathy can present with features like chronic progressive external ophthalmoplegia (CPEO), muscle weakness, esophageal reflux, proptosis, and characteristic muscle MRI findings, and is associated with novel mutations [2]. Recessive MYH2 mutations can lead to early-onset myopathy with complete loss of type 2A fibers, while some cases with recessive genotypes may present with phenotypes typical of dominant forms [3]. Neonates with MYH2 myopathy may show hypotonia, dysphagia, dysmorphic features, and specific muscle biopsy findings [4]. An adult patient with MYH2-myopathy due to two heterozygous pathogenic variants presented a novel myopathological phenotype including filamentous tangles with nemaline rods [5].

In conclusion, Myh2 is essential for normal muscle function. Studies using genetic models, although not explicitly detailed in the provided references, could potentially further clarify its role. The identification of MYH2-related myopathies and their associated mutations from the references contributes to understanding the molecular mechanisms of these muscle-related diseases, which may aid in the development of diagnostic and treatment strategies for myopathies.