Italian Anderson Fabry Disease Cardiovascular Registry

1. Introduction

Anderson-Fabry Disease (AFD) is a multisystemic lysosomal storage disorder with X-linked inheritance (Online Mendelian Inheritance in Man [OMIM] number 301500) caused by a total or partial deficiency of the enzyme α-galactosidase A (α-Gal A), encoded by the GLA gene (Xq22.1). The deficiency of α-Gal A leads to the accumulation of neutral glycosphingolipids, particularly globotriaosylceramide (Gb3) and galactosylceramide, in various cell types and tissues. The continuous accumulation of these molecules results in progressive cellular dysfunction, triggering inflammatory and pro-fibrotic phenomena that cause organ dysfunction.

The clinical manifestations and age of onset of the disease are highly variable, and symptoms/signs often appear only after a degree of irreversible damage has already occurred. The classic form of AFD is the most severe clinical phenotype and predominantly affects males with null or minimal residual enzymatic activity (<1% of normal values). Symptoms begin early during childhood or adolescence and include acroparesthesias, angiokeratomas, telangiectasias, gastrointestinal disturbances, corneal alterations (cornea verticillata), proteinuria, renal insufficiency, hypo/hyperhidrosis, and hearing loss. Later in adulthood, progressive cardiac and cerebrovascular involvement may occur.

Patients with atypical or late-onset variants generally develop the disease later (from the third to the seventh decade of life) compared to those with the classic form. The clinical picture is generally dominated by the involvement of a single organ, most frequently the heart. The measurement of residual enzymatic activity of α-Gal A is sufficient to establish a diagnosis in males. However, it is important to identify the specific genetic mutation to determine the disease phenotype and exclude benign polymorphisms that may cause reduced enzymatic activity levels. In females, genetic diagnosis is indispensable, as residual enzymatic activity often falls within the normal range.

The treatment of AFD is based on compensating for the deficient enzymatic activity through enzyme replacement therapy (ERT) and managing the disease's symptoms and complications. More recently, an oral chaperone therapy capable of increasing residual enzymatic activity has been approved, though it is only effective for certain mutation types. Given the multisystemic involvement in AFD patients, longitudinal multispecialty evaluation is necessary, including cardiology, nephrology, neurology, dermatology, ophthalmology, and otorhinolaryngology assessments.