Sex-Specific Expression Patterns of MYH6 and MYH7 Gene Transcripts in Large Cohorts of Non-Failing and Failing Human...

The transcriptional regulation of MYH6 and MYH7 genes has been extensively investigated in healthy versus failing hearts; however, their expression dynamics in healthy human hearts across age and sex, particularly in the context of cardiovascular risk factors such as hypertension, remain poorly characterised. This study aimed to carry out a reanalysis of MYH6 and MYH7 transcript levels in a large cohort of non-failing human left ventricular samples, stratified by sex, age, and hypertensive status. Furthermore, we examined how age and sex influence gene expression differences between non-failing and failing hearts, the latter affected by dilated cardiomyopathy (DCM). Normalised expression values for MYH6 and MYH7 transcripts from both healthy and failing left ventricles were extracted using the GEO2R online analysis tool from the publicly available RNA-sequencing library GSE141910. This library provides transcriptomic profiles of left ventricular (LV) tissue from both healthy individuals and patients with cardiomyopathies. The Mann-Whitney U test was employed for pairwise comparisons between different groups stratified by sex, age, and hypertensive status. Statistical analysis demonstrates sex-specific differences in MYH6 and MYH7 expression in healthy left ventricles, with postmenopausal females (aged > 50 years) with hypertension emerging as a distinct group. Conversely, in end-stage DCM hearts, the expression levels of both myosin genes seemed to be primarily influenced by disease-related pathophysiological mechanisms rather than by sex or age. Comparison between healthy and failing hearts revealed a consistent and significant downregulation of MYH6 in all comparisons, irrespective of sex or age. On the other hand, MYH7 expression exhibited greater variability, particularly among males, with age and hypertensive status influencing its expression. The results underscore the importance of considering age, sex, and comorbidities in interpreting cardiac gene expression patterns and highlight potential regulatory divergence in contractile gene expression during cardiac remodelling.