Anderson–Fabry disease is a lysosomal storage disorder caused by mutations in the GLA gene, which encodes the enzyme α-galactosidase A. The GLA gene is located on the X-chromosome, causing an X-linked pathology: due to lyonization, female patients usually manifest a variable symptomatology, ranging from asymptomatic to severe phenotypes. The confirmation of the clinical diagnosis of Fabry disease, achieved by measuring α-galactosidase A activity, which is usually the first test used, shows differences between male and female patients. This assay is reliable in male patients with causative mutations in the GLA gene, in whom the enzymatic activity is lower than normal values; on the other hand, in female Fabry patients, the enzymatic activity is extremely variable between normal and pathological values. These fluctuations are also found in female patients’ blood levels of globotriaosylsphingosine (LysoGb3) for the same reason. In this paper, we present a retrospective study conducted in our laboratories on 827 Fabry patients with causative mutations in the GLA gene. Our results show that 100% of male patients had α-galactosidase A activity below the reference value, while more than 70% of female patients had normal values. It can also be observed that almost half of the female patients with pathogenic mutations in the GLA gene showed normal values of LysoGb3 in blood. Furthermore, in women, blood LysoGb3 values can vary over time, as we show in a clinical case presented in this paper. Both these tests could lead to missed diagnoses of Fabry disease in female patients, so the analysis of the GLA gene represents the main diagnostic test for Fabry disease in women to date.

Fabry disease (FD) is an X-linked lysosomal storage disease, caused by mutations in the GLA gene on the X chromosome, resulting in a deficiency of the lysosomal enzyme α-GAL. This leads to the progressive accumulation of Gb3 in cells, causing multi-systemic effects. FD has been classified as a subgroup of autoinflammatory diseases. NF-κB is a family of ubiquitous and inducible transcription factors that play critical roles in inflammation, in which the p65/p50 heterodimer is the most abundant. The glucocorticoid receptor (GR) represents the physiological antagonists in the inflammation process. A novel spliced variant of p65, named p65 iso5, which can bind the dexamethasone, enhancing GR activity, has been found. This study investigates the potential role of p65 iso5 in the inflammation of subjects with FD. We evaluated in peripheral blood mononuclear cells (PBMCs), from over 100 FD patients, the p65 iso5 mRNA level, and the protein expression. The results showed significantly lower p65 iso5 mRNA and protein expression levels compared to controls. These findings, along with the ability of p65 iso5 to bind dexamethasone and the regulation of the glucocorticoid response in the opposite way of p65, strongly suggest the involvement of p65 iso5 in the inflammatory response in FD.

Anderson–Fabry disease is a hereditary, progressive, multisystemic lysosomal storage disorder caused by a functional deficiency of the enzyme α-galactosidase A (α-GalA). This defect is due to mutations in the GLA gene, located in the long arm of the X chromosome (Xq21-22). Functional deficiency of the α-GalA enzyme leads to reduced degradation and accumulation of its substrates, predominantly globotriaosylceramide (Gb3), which accumulate in the lysosomes of numerous cell types, giving rise to the symptomatology. Clinical diagnosis can still be difficult today due to the peculiarities of the disease, which presents with clinical manifestations that overlap with those of other pathologies and a wide possibility of differential diagnoses, which lead to missed diagnoses, misdiagnosis, or a diagnostic delay. Patients with clinical suspicion of Fabry disease undergo a diagnostic workup that includes an evaluation of α-GALA enzyme activity, genetic analysis of the GLA gene, and the measurement of blood Lyso-Gb3, a soluble derivative of Gb3. In this paper, we describe four novel mutations identified in the GLA gene which are associated with absent or reduced α-GalA activity, pathological accumulation of the specific substrate, and characteristic clinical manifestations of Fabry disease. We identified two mutations (c.583insGAATA and p.Y207X) that result in the formation of a premature translation stop codon, resulting in a truncated protein and thus a completely non-functional enzyme. The other two identified gene alterations (p.G261C and c.786G>T, which determine p.W262C) are missense mutations that cause reduced α-GALA activity, the accumulation of blood Lyso-Gb3, and symptoms consistent with Fabry disease, and therefore may be associated with this disorder. The identification of these new mutations in patients with symptoms attributable to Fabry disease increases the molecular knowledge of the GLA gene and provides important support to the clinician, for a more accurate and timely diagnosis of the pathology.

Anderson–Fabry (or Fabry) disease is a rare lysosomal storage disorder caused by a functional deficiency of the enzyme alpha-galactosidase A. The partial or total defect of this lysosomal enzyme, which is caused by variants in the GLA gene, leads to the accumulation of glycosphingolipids, mainly globotriaosylceramide in the lysosomes of different cell types. The clinical presentation of Fabry disease is multisystemic and can vary depending on the specific genetic variants associated with the disease. To date, more than 1000 different variants have been identified in the human GLA gene, including missense and nonsense variants, as well as small and large insertions or deletions. The identification of novel variants in individuals exhibiting symptoms indicative of Fabry disease, expands the molecular comprehension of the GLA gene, providing invaluable insights to physicians in the diagnosis of the disease. In this article, we present the case of two members of the same family, mother and son, in whom a new pathogenic variant was identified. This variant has not been previously described in the literature and is not present in databases. The two family members presented with a number of typical clinical manifestations of the disease, including cornea verticillata, neuropathic pain, left ventricular hypertrophy, angiokeratomas and abdominal pain. The son, but not his mother, showed reduced alpha-galactosidase A activity, while high levels of Lyso-Gb3 in the blood, a specific substrate accumulation biomarker, were found in both. Sequencing of the GLA gene revealed the presence of a variant, c.484delT, which is characterised by the deletion of a single nucleotide, a thymine, in exon 3 of the gene. This results in a frameshift variant, which introduces a premature stop codon, thereby generating a truncated and consequently non-functional protein. Therefore, the clinical and laboratory data indicate that the novel p.W162Gfs*3 variant described herein is associated with the classical form of Fabry disease.

Gaucher disease is an autosomal recessive disorder caused by dysfunction of the enzyme glucocerebrosidase. The enzyme deficiency is mainly due to mutations in the GBA1 gene, and it is responsible for the accumulation of glucosylceramide within the lysosomes of monocyte macrophage-derived cells; causing the associated symptomatology. In this paper, we describe six new mutations identified in the GBA1 gene, which, in combination with other mutations already documented, lead to absent or reduced glucocerebrosidase activity, resulting in pathological accumulation of the specific substrate and the clinical manifestations associated with Gaucher disease. We have identified three mutations (c.1578_1581dup, c.1308dup, and Y492X) that determine the formation of a premature stop codon in the translation process and three missense mutations (C342F, M280L, and Q247R) that lead to amino acid changes in proteins, resulting in decreased glucocerebrosidase activity. These mutations were never observed in our group of healthy control subjects > 1500 individuals. The patients examined had several clinical manifestations, which included hepatosplenomegaly and bone and hematologic involvement; considering the absence of enzyme activity, this suggests that the new mutations described here are associated with type I Gaucher disease. The identification of new mutations in patients with symptoms referable to Gaucher disease increases the molecular knowledge related to the GBA1 gene and offers to clinicians significant support for the accurate diagnosis of the pathology.

Background: Multiplex Ligation Probe Amplification (MLPA) is a widely used technique for the diagnosis of lysosomal storage diseases (LSDs). It analyses over 40 DNA sequences in a single reaction, identifying copy number variations and large deletions/insertions in genes. The diagnostic process in LSDs starts with analysis of the missing or reduced enzyme, followed by genetic investigation and, if possible, a search for accumulated substrates. However, while genetic analysis using Sanger sequencing is excellent at detecting small genetic variations such as single-nucleotide variants (SNVs) and small insertions or deletions, it cannot detect large deletions or insertions. Methods: In the present study, a total of 800 patients with clinical suspicion of Fabry, Gaucher, or Pompe diseases were investigated. An enzyme assay was carried out on each patient, followed by genetic analysis using PCR, Sanger sequencing, and MLPA. Results: Nine patients with deficient or absent enzyme activity had Sanger sequencing results that could not confirm the molecular genetic diagnosis because either no mutation (Fabry) or only one mutation (Gaucher and Pompe) was identified. Subsequent analysis by MLPA identified two males with a hemizygous deletion and two females with a heterozygous deletion for FD. For PD, one female and two males had a heterozygous deletion. For GD, one male had a homozygous deletion and one female had a heterozygous deletion. The remaining patients were analyzed by MLPA with negative results. Conclusions: The results obtained suggest that MLPA should be used in combination with classical sequencing methods to ensure a correct and timely diagnosis of LSDs.