New insights into the correlation between genotype and cardiac phenotype in laminopathies
Authors: Dusi V , Angelini F , Elia S , Pidello S , Vairo A , Callegari M , Golzio P G , Castagno D , Ferraris F , Anselmino M , Giustetto C , Deaglio S , Mongini T , Raineri C , De Ferrari G M 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
Genotype-phenotype correlation and risk stratification for heart failure progression in patients with cardiolaminopathies are poorly defined.

Purpose
The primary aim of the present study is to characterize and correlate phenotype with genotype and sex. The secondary aim is to test the two main existing prognostic scores (the Arbustini and the Whabi score), both developed to predict ventricular arrhythmic events in cardiolaminopathies, for both major ventricular arrhythmias (MVA) and end-stage heart failure (ESHF).

Methods
This is a retrospective, single-center study, including patients with lamin (LMNA) and/or emerin (EMD) genetic variants. Data were collected from the first medical contact (FMC) to the last follow-up (FU).

Results
28 patients (57% male, 82% probands, 68% with a family history of sudden death) were included: 96% harbored LMNA heterozygous variants, 15% had non-missense variants, 11% had variant previously never described. Functionally, 50% were variant of undetermined significance (VUS, C3), the rest were either pathogenetic or likely pathogenic (C4/C5) variants. Median age at FMC was 41 years (IQR 30-55 years), median FU was 11 years (IQR 8-18 years). At FMC, all patients had cardiac involvement, 54% had muscle involvement. By the last FU, 54% developed atrial fibrillation, 43% atrioventricular block (AVB) &gt; I degree, 50% carried an implantable cardioverter defibrillator (21% with resynchronization), 50% had suffered at least one episode of MVA, 25% developed ESHF: 11% died due to refractory HF, 14% underwent heart transplantation (mean age 43.5 ± 9 years). The age of onset of the different types of cardiac phenotype was not influenced by sex.
The penetrance of atrioventricular (AV) conduction defects (Figure 1 Panel A) and of atrial tachyarrhythmias (Figure 1 Panel B) was higher and earlier in subjects with non-missense variants. Subjects with VUS, compared to those with pathogenetic/likely pathogenetic variants, showed a significantly lower and later penetrance of MVA (Figure 2 Panel A) and a later penetrance of non- sustained ventricular tachycardia (NSVT, Figure 2, Panel B), but not of AV conduction disturbances, atrial arrhythmias, or contractile dysfunction. Arbustini score at FMC proved to be a predictor of both MVA and ESHF, while Whabi score only predicted MVA.

Conclusions
In our series, the prevalence and the age of appearance of the different cardiac phenotypes of cardiolaminopathies were not influenced by sex, while the presence of VUS correlated with a lower risk of ventricular arrhythmias, but not of the other cardiac manifestations including contractile disfunction and heart failure. Our data suggest the importance of a close cardiac monitoring and of larger prospective studies even in patients with VUS. All patients developed a sever cardiac phenotype by the age of 60.