Genetic analysis of monoallelic double MYH7 mutations responsible for familial hypertrophic cardiomyopathy

Myocardial contractility characteristics of hypertrophic cardiomyopathy patients with and without sarcomere mutation

Hypertrophic cardiomyopathy (HCM) patients with sarcomere mutations have an increased risk of heart failure and left ventricular (LV) systolic dysfunction. We hypothesize that sarcomere mutation carriers have abnormal myocardial contractility before LV dysfunction. Therefore, we aimed to associate myocardial contractility with identified sarcomere mutations and predict genotyped HCM patients with sarcomere mutation by three-dimensional speckle tracking imaging (3D-STI). A retrospective analysis of 117 HCM patients identified 32 genotype-positive (G +) and 85 genotype-negative (G-) patients. Genotype-positive patients had higher globe circumferential strain (GCS), globe longitudinal strain (GLS), and globe radial strain (GRS) (p < 0.05), and multivariate logistic regression revealed that these variables were associated with a positive genetic status (p < 0.05). After the propensity matches other possible influencing factors, we developed three models, named Model GCS, Model GLS, and Model GRS, which could identified genotype-positive HCM patients with excellent performance (AUC of 0.855, 0.833, and 0.870 respectively, all p < 0.001). Genotype-positive HCM patients show a higher myocardial hyper-contractility status than patients without sarcomere mutations. When combined with clinical and echocardiographic markers, the 3D-STI parameters can effectively identify the likelihood of genotype-positive HCM.

MYH7 in cardiomyopathy and skeletal muscle myopathy

Myosin heavy chain gene 7 (MYH7), a sarcomeric gene encoding the myosin heavy chain (myosin-7), has attracted considerable interest as a result of its fundamental functions in cardiac and skeletal muscle contraction and numerous nucleotide variations of MYH7 are closely related to cardiomyopathy and skeletal muscle myopathy. These disorders display significantly inter- and intra-familial variability, sometimes developing complex phenotypes, including both cardiomyopathy and skeletal myopathy. Here, we review the current understanding on MYH7 with the aim to better clarify how mutations in MYH7 affect the structure and physiologic function of sarcomere, thus resulting in cardiomyopathy and skeletal muscle myopathy. Importantly, the latest advances on diagnosis, research models in vivo and in vitro and therapy for precise clinical application have made great progress and have epoch-making significance. All the great advance is discussed here.

Phenotype variation of hypertrophic cardiomyopathy in carriers of the p.Arg870His pathogenic variant in the MYH7 gene

The review analyzes variability of clinical manifestations of p.Arg870His in the MYH7 gene, which is repeatedly registered in patients with hypertrophic cardiomyopathy (HCM). The analysis involves the data from scientific publications obtained as a search result in the PubMed, СlinVar, and eLibrary.ru databases, as well as authors’ own results. A wide range of phenotypic manifestations have been revealed in carriers of p.Arg870His, from the asymptomatic to severe course, rapid progression, and early death. The review considers possible factors that modify the effect of the pathogenic variant (i.e. dosage of the pathogenic variant, the presence of other unfavorable genetic variants, etc.). The importance of accumulating information on the clinical features of HCM in the carriers of specific gene variants is emphasized in order to clarify their pathogenicity and to identify factors modifying the clinical outcome, which is important for the choice of the treatment strategy for HCM.

Genetic variant affecting the myosin light chain 2 related to familial hypertrophic cardiomyopathy

Familial hypertrophic cardiomyopathy (FHCM) is a genetic disease characterized by left ventricle (LV) or interventricular septum hypertrophy. FHCM is a common heart disease (affecting 1 out of 500 individuals) associated with genetic variants in genes related to the sarcomere, including the MYL2 (myosin light chain 2) gene that is affected in 1 to 3% of the cases. As described in this report, the genetic mutation p.Gly87Ala, rs 397516399 in the MYL2 gene is likely pathogenic. Reported here is the case of a 37-year-old Colombian man with asymmetric septal hypertrophic cardiomyopathy and ventricular tachycardia. The man had progressive symptomatology, a family history of FHCM with a dominant inheritance pattern, a mother and 2 brothers with FHCM, and 2 brothers who died suddenly before the age of 35. A molecular panel of 17 genes for hypertrophic cardiomyopathy identified a heterozygous variant, p.Gly87Ala, of the MYL2 gene. This variant can be found in Ensembl, dbSNP, and ClinVar, where it has conflicting interpretations: it either has an uncertain significance or it is likely pathogenic. This is the first report of a Colombian case of FHCM secondary to a mutation in the MYL2 gene, highlighting the importance of molecular diagnosis, genetic counseling, and bioinformatic analysis in these patients.