Myh11, encoding smooth muscle myosin heavy chain, is selectively expressed in smooth muscle cells (SMCs) [3]. It is crucial for maintaining the contractility and structural integrity of smooth muscles, playing a role in normal physiological functions related to SMC activities.

Pathogenic variants in Myh11 have been linked to multiple disorders. In a mouse model with Myh11 K1256del, the aorta showed increased wall thickness, ultrastructural abnormalities, and reduced contractility, leading to aortic dissections and intramural haematomas when stimulated, suggesting that Myh11 is essential for aortic integrity and function [2]. Myh11 E1892D/E1892D mutant mice had augmented ascending aortic enlargement and increased elastic fragmentation after transverse aortic constriction (TAC), and male mutants had decreased cardiac function, indicating its role in aortic growth and cardiac response to pressure overload [3]. Also, in patients with MYH11 -variant visceral myopathy, routine histopathological and electron microscopy evaluations showed no myopathic morphological changes, but molecular genetic studies are still necessary for diagnosis [4]. In the context of acute myeloid leukemia with CBFB-MYH11, loss of chromosome X or Y and NRAS mutation were poor prognostic factors for relapse-free survival [1].

In conclusion, Myh11 is vital for maintaining the normal function of smooth muscles, especially in the aorta. Mouse models with Myh11 mutations have revealed its significance in aortic-related diseases. Additionally, in certain leukemia cases, the genetic context associated with MYH11 can influence prognosis. These findings enhance our understanding of the biological functions of Myh11 and its implications in disease.