In this issue of the Journal, Brito et al. present a very interesting work1 based on data extracted from the Portuguese Registry of Hypertrophic Cardiomyopathy.2

Focusing on a non-mandatory question from this registry, concerning the exclusion of Anderson-Fabry disease in the differential diagnosis, the authors concluded that this entity is seldom studied in the workup of patients with unexplained left ventricular hypertrophy. According to their data, Fabry disease was recorded as excluded in only 27% of the patients included in the registry. Alpha-galactosidase A (α-Gal A) activity was assessed in 18% and GLA gene testing was only performed in 23% of cases. Among patients with potential red flags for Fabry disease (including concentric left ventricular hypertrophy, short or prolonged PR interval, intraventricular conduction disturbances or bradyarrhythmias requiring pacemaker implantation), fewer than half (47%) underwent specific tests (GLA gene testing and/or α-Gal A activity).

These results are even more striking if we note that only cardiology departments were included in the registry, which is totally voluntary, and that inclusion was not sequential. Bearing this in mind, there is a high probability of bias toward the inclusion of better-studied patients and a higher participation of centers with better overall performance in cardiomyopathies. This means that in real-world practice the rates of Fabry disease exclusion in these patients are probably even lower than reported here.

Portugal has some of the largest series of Fabry disease patients in Europe, and these numbers are mainly due to the systematic diagnostic workup performed in reference centers for lysosomal storage diseases.3–6 Although some geographic distribution patterns are clearly discernible, as can be expected from an X-linked genetic disease, it is essential to maintain general awareness of this disease, for which specific therapies are available that can modify prognosis. Since cardiac involvement is frequent and is sometimes the primary or sole manifestation of Fabry disease, all cardiologists should be constantly on the alert for the possibility of Fabry disease in the study of unexplained left ventricular hypertrophy. Early diagnosis and, if appropriate, initiation of enzyme replacement therapy can change the course of this disease and may improve both symptoms and prognosis. Furthermore, identification of an index case can help identify relatives affected by disease, who may also benefit from diagnostic workup, structured follow-up and early initiation of therapy, if indicated.

In an era of advanced imaging and readily available genetic testing, efforts should be made to ensure that red flags for Fabry disease in patients with left ventricular hypertrophy are identified and to encourage the use of dedicated tools for its exclusion. This paper has a clear message for all cardiologists: Fabry disease is something that must always be borne in mind in the study of patients with unexplained left ventricular hypertrophy.