RESUMEN
Background: Left ventricular noncompaction (LVNC) cardiomyopathy is a disorder that can be complicated by heart failure, arrhythmias, thromboembolism, and sudden cardiac death. The aim of this study is to clarify the genetic landscape of LVNC in a large cohort of well-phenotyped Russian patients with LVNC, including 48 families (n=214). Methods: All index patients underwent clinical examination and genetic analysis, as well as family members who agreed to participate in the clinical study and/or in the genetic testing. The genetic testing included next generation sequencing and genetic classification according to ACMG guidelines. Results: A total of 55 alleles of 54 pathogenic and likely pathogenic variants in 24 genes were identified, with the largest number in the MYH7 and TTN genes. A significant proportion of variants -8 of 54 (14.8%) -have not been described earlier in other populations and may be specific to LVNC patients in Russia. In LVNC patients, the presence of each subsequent variant is associated with increased odds of having more severe LVNC subtypes than isolated LVNC with preserved ejection fraction. The corresponding odds ratio is 2.77 (1.37 -7.37; p <0.001) per variant after adjustment for sex, age, and family. Conclusion: Overall, the genetic analysis of LVNC patients, accompanied by cardiomyopathy-related family history analysis, resulted in a high diagnostic yield of 89.6%. These results suggest that genetic screening should be applied to the diagnosis and prognosis of LVNC patients.
RESUMEN
Variants of the MYH7 gene have been associated with a number of primary cardiac conditions, including left ventricular noncompaction cardiomyopathy (LVNC). Most cases of MYH7-related diseases are associated with such variant types as missense substitutions and in-frame indels. Thus, truncating variants in MYH7 (MYH7tv) and associated mechanism of haploinsufficiency are usually considered not pathogenic in these disorders. However, recent large-scale studies demonstrated evidence of the significance of MYH7tv for LVNC and gave rise to an assumption that haploinsufficiency may be the causal mechanism for LVNC. In this article, we present a family with isolated LVNC and a heterozygous splice variant of the MYH7 gene, analyze possible consequences of this variant and conclude that not all variants that are predicted truncating really act through haploinsufficiency. This study can highlight the importance of a precise assessment of MYH7 splicing variants and their participation in the development of LVNC.
Asunto(s)
Cardiomiopatías , No Compactación Aislada del Miocardio Ventricular , Humanos , No Compactación Aislada del Miocardio Ventricular/genética , Mutación , Corazón , Mutación Missense , Cadenas Pesadas de Miosina/genética , Miosinas Cardíacas/genéticaRESUMEN
Mutations in DES, encoding desmin protein, are associated with different kinds of skeletal and/or cardiac myopathies. However, it is unknown, whether DES mutations are associated with left ventricular hypertrabeculation (LVHT). Here, we performed a clinical examination and subsequent genetic analysis in a family, with two individuals presenting LVHT with conduction disease and skeletal myopathy. The genetic analysis revealed a novel small in-frame deletion within the DES gene, p.Q113_L115del, affecting the α-helical rod domain. Immunohistochemistry analysis of explanted myocardial tissue from the index patient revealed an abnormal cytoplasmic accumulation of desmin and a degraded sarcomeric structure. Cell transfection experiments with wild-type and mutant desmin verified the cytoplasmic aggregation and accumulation of mutant desmin. Cotransfection experiments were performed to model the heterozygous state of the patients and revealed a dominant negative effect of the mutant desmin on filament assembly. DES:p.Q113_L115del is classified as a pathogenic mutation associated with dilated cardiomyopathy with prominent LVHT.