Early biomarkers of disease in hypertrophic cardiomyopathy: does telomere length matter?

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Biomedical Research Institute of Murcia (IMIB-Arrixaca) Introduction Hypertrophic cardiomyopathy (HCM) is the leading cause of sudden death in people under 35 years of age. (1) The variability of the phenotype together with its incomplete penetrance has been an obstacle to a complete understanding of the clinical spectrum and consequences of the disease. In recent years, there has been increasing interest in telomeric shortening and several authors have linked it to age-related diseases and HCM. (2, 3) Our aim was to study whether telomere length could affect the age at presentation and the severity of the HCM phenotype in genetic carriers. Methods Measurement of telomere length in circulating leukocytes (LTLc) was performed in 96 patients carrying a mutation in MYBPC3 causing HCM [58 affected (24 severely affected), 38 unaffected]. The variants included were c.2308+1G>A, p.Pro108Alafs*9, p.Arg891Alafs*160 and p.Glu258Lys, all considered founder mutations in our region. Peripheral venous blood samples were obtained from patients at the Inherited Heart Diseases Unit and stored at -80 ºC after informed consent had been signed by all participants. For telomere length analysis, a telomeric restriction fragment (TRF) assay was performed using the TeloTAGGGTelomereLenghtAssay kit (Roche, 12209136001) according to the manufacturer's protocol with slight modifications. Results Our results show a lower LTLc in those affected patients with a more severe HCM phenotype compared to the affected and unaffected group (p=0.023) independently of age and sex, which are two variables that affect LTLc. Similarly, a shorter telomere length was associated with greater severity of the phenotype, with patients presenting a larger left atrial size (p=0.032), septal size (p=0.023) and greater obstruction (p=0.044). The presence of atrial fibrillation (p=0.039) and sudden death (p=0.024) was also higher in patients with shorter telomeres. Conclusions Telomere length is a variable that influences the expression of the phenotype in HCM patients carrying a MYBPC3 variant. This is an observation that supports the thesis of numerous publications linking HCM and other age-related diseases, sometimes called telomeropathies,(2) to telomere shortening. It has also been linked to non-hereditary conditions(3). This fact sheds some light on the complex phenotypic variability present in HCM, raising LTL as a promising prognostic biomarker of the disease, as has already been suggested by other authors.(4, 5, 6).Workflow in the telomere legth analysisClinical associations of LTLc