Cardiomyopathy associated with the Ala143Thr variant of the <i>α-galactosidase A</i> gene.

Abstract

To investigate whether the Ala143Thr variant of the <i>α-galactosidase A</i> gene (A143T/<i>GLA</i>), with conflicting interpretations of pathogenicity, is associated with Fabry cardiomyopathy. The index patient, a woman in her 60s with cardiomyopathy, was screened for variants in 59 cardiomyopathy-related genes. A143T/<i>GLA</i>, the only rare variant found, was screened in 10 relatives. GLA activity and lyso-Gb3 levels were measured and echocardiography was performed in 8 of 9 subjects carrying A143T/<i>GLA</i>. Cardiac magnetic resonance (CMR) imaging and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/CT (PET/CT) were performed in four adult A143T/<i>GLA</i> carriers. Endomyocardial biopsy was obtained from two adult A143T/<i>GLA</i> carrying sons of the index patient. The index patient and her elder son had a pacemaker implantation because of sick sinus syndrome and atrioventricular block. GLA activities were decreased to 25%-40% of normal in both sons and one granddaughter. Lyso-Gb3 levels were elevated in both sons. In CMR, the index patient and her two sons had left ventricular (LV) hypertrophy and/or dilatation. The elder son had late gadolinium enhancement, high CMR-derived T1 time and positive FDG signal in PET/CT in the basal inferolateral LV wall. The younger son had low T1 time and the mother had positive FDG signal in PET/CT in the basal inferolateral LV wall. Endomyocardial biopsy of both sons showed myocardial accumulation compatible with glycolipids in light and electron microscopy, staining with anti-Gb3 antibody available for the younger son. Five female relatives with A143T/<i>GLA</i> had no cardiomyopathy in cardiac imaging. A143T/<i>GLA</i> is likely a late-onset Fabry cardiomyopathy causing variant with incomplete penetrance.