Phenotypic Expression and Outcomes in Patients with the p.Arg301Gln GLA Variant in Anderson-Fabry Disease

The p.Arg301Gln variant in the α -galactosidase A gene (GLA) has been poorly described in the literature. The few reports show controversial information, with both classical and nonclassical Anderson-Fabry Disease (AFD) presentation patterns. The aim of this study was to analyze the penetrance, clinical phenotype, and biochemical profile of an international cohort of patients carrying the p.Arg301Gln genetic variant in the GLA gene. This was an observational, international, and retrospective cohort case series study of patients carrying the p.Arg301Gln variant in the GLA gene associated with AFD disease. Forty-nine p.Arg301Gln GLA carriers, 41% male, were analyzed. The penetrance was 63% in the entire cohort and 1.5 times higher in men. The mean age of symptoms onset was 41 years; compared to women, men presented symptoms earlier and with a shorter delay to diagnosis. The typical clinical triad-cornea verticillate, neuropathic pain, and angiokeratomas-affected only 20% of the cohort, with no differences between genders. During follow-up, almost 20% of the patients presented some type of nonfatal cardiovascular and renal event (stroke, need for dialysis, heart failure, and arrhythmias requiring intracardiac devices), predominantly affecting men. Residual levels were the most common finding of α-GAL A enzyme activity, only a few women had a normal level; a small proportion of men had undetectable levels. The incidence of combined outcomes including all causes of death was 33%, and the cumulative incidence of all-cause mortality was 9% at the follow-up. Patients carrying the p.Arg301Gln GLA variant have a high penetrance, with predominantly cardiorenal involvement and clinical onset of the disease in middle age. Only a small proportion showed the classic clinical presentation of AFD. As in other X-linked diseases, males were more affected by severe cardiovascular and renal events. This genotype-phenotype correlation could be useful from a practical clinical point of view and for future decision making.

Genotype-phenotype correlation and allele dating analysis of a novel variant in hypertrophic cardiomyopathy: p.Arg652Lys in MYH7

Background/Introduction

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterised by increased left ventricle (LV) wall thickness caused by mutations in sarcomeric genes. Finding a causal mutation can help to better assess the proband's risk, as it allows the presence of the mutation to be evaluated in relatives and the follow-up to be focused on carriers.

Purpose

The objectives of the present study are to assess the genotype-phenotype correlation of a novel variant found in patients with HCM and explore the possibility of a founder effect in the Balearic Islands, Spain.

Methods

We performed an observational study with phenotype description and genotype correlation of patients with HCM in whom we found a novel variant in the MYH7 gene (NM_000257.4:c.1955G>A) which putatively causes a p.Arg652Lys missense protein change.

We did IBD/coalescent-based allele dating analysis of this novel variant.

Results

This previously non-described variant was found in twelve families with HCM. Out of those, 59 patients corresponding to 8 families were clinically characterized with a median follow-up of 63 months. Among them, 39 (66%) carry the variant. Twenty-five (64%) of carriers developed HCM. A median maximum LV wall thickness of 16.5 mm was described. The LV hypertrophy was asymmetric septal in 75% of cases, with LV outflow tract obstruction in 28%. The incidence of a composite of serious adverse cardiovascular events (sudden death, aborted sudden death, appropriate implantable cardiac defibrillator dis-charge, an embolic event, or admission for heart failure) was observed in five (20%) patients.

This p.Arg652Lys variant was classified as likely pathogenic (LP) and associated with the development of HCM for the following reasons: 1) It is found in patients with HCM, but not in controls, 2) There is evident segregation with HCM on the 8 families described, and 3) It is located in an active site of the protein where a variant in the same amino acid has already been clearly established as pathogenic (p.Arg652Gly).

Interestingly, the exclusive presence of the variant in our region could correspond to a founder effect in the Balearic Islands, Spain, which we have further investigated. IBD/coalescent-based allele dating analysis reveals that the origin of this allele is 96 generations away which would correspond to 1900–2400 years ago, when the Balearic Islands were already populated.

Conclusions

We can define the p.Arg652Lys variant in MYH7 as LP in HCM and a founder effect is in the Balearic Islands is highly probable due to the exclusive presence at the region and the dating analysis of it.

Funding Acknowledgement

Type of funding sources: None.

Genotype-Phenotype Correlation in Hypertrophic Cardiomyopathy: New Variant p.Arg652Lys in MYH7

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterised by increased left ventricle (LV) wall thickness caused by mutations in sarcomeric genes. Finding a causal mutation can help to better assess the proband’s risk, as it allows the presence of the mutation to be evaluated in relatives and the follow-up to be focused on carriers. We performed an observational study of patients with HCM due to the novel p.Arg652Lys variant in the MYH7 gene. Eight families and 59 patients are described in the follow-up for a median of 63 months, among whom 39 (66%) carry the variant. Twenty-five (64%) of carriers developed HCM. A median maximum LV wall thickness of 16.5 mm was described. The LV hypertrophy was asymmetric septal in 75% of cases, with LV outflow tract obstruction in 28%. The incidence of a composite of serious adverse cardiovascular events (sudden death, aborted sudden death, appropriate implantable cardiac defibrillator discharge, an embolic event, or admission for heart failure) was observed in five (20%) patients. Given the finding of the p.Arg652Lys variant in patients with HCM, but not in controls, with evident segregation in patients with HCM from eight families and the location in an active site of the protein, we can define this variant as likely pathogenic and associated with the development of HCM.

Detection and quantification of bar breakage harmonics evolutions in inverter-fed motors through the dragon transform

The problem of detecting and quantifying bar breakage harmonics in inverter-fed induction motors has not been solved by the time-frequency transforms present in the technical literature. The paper proposes a new transform, called dragon transform, to solve this problem. The dragon atoms are defined with shapes perfectly adapted to the harmonic trajectories in the time-frequency plane, no matter how complex they are, enabling the precise tracing of the harmonics to be detected. A quantification method is also proposed, which obtains for the first time in the technical literature, the time evolutions of the harmonic amplitudes during a complex transient such as the start-up and the steady state of an inverter-fed motor. The transform performance is validated testing the induction motor under different load levels.