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.

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.

Pompe disease is a neuromuscular disorder caused by a deficiency of the enzyme acid alpha-glucosidase (GAA), which leads to lysosomal glycogen accumulation and progressive development of muscle weakness. Two distinct isoforms have been identified. In the infantile form, the weakness is often severe and leads to motor difficulties from the first few months of life. In adult patients, the progression is slower but can still lead to significant loss of mobility. The current inherent difficulties of the disease lie in both early diagnosis and the use of biomarkers. Given that this is a multifactorial disease, a number of components may exert an influence on the disease process; from the degree of pre-ERT (enzyme replacement therapy) muscle damage to the damaged autophagic system and the different pathways involved. What methodology should be employed to study the complex characteristics of Pompe disease? Our approach relies on the application of genetic and epigenetic knowledge, with a progression from proteomics to transcriptomics. It is also becoming increasingly evident that artificial intelligence is a significant area of interest. The objective of this study is to conduct a comprehensive review of the existing literature on the known data and complications associated with the disease in patients with disorders attributed to Pompe 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.

This case report describes a 22-year-old woman with a phenotype compatible with Gaucher disease, characterized by hepatomegaly, splenomegaly, and thrombocytopenia. β-glucocerebrosidase activity was lower than reference values, making further genetic testing necessary. Sanger sequencing of the GBA1 gene revealed the presence of the pathogenic variant p.N409S in apparent homozygosity. Plasma glucosylsphingosine (Lyso-Gb1) testing provided further biochemical support for the diagnosis. Family screening, by Sanger sequencing, showed that the father is a heterozygous carrier of the p.N409S variant, while the mother and brother do not have any variants in the GBA1 gene. The absence of the maternal variant suggested the possible presence, in the proband, of a second structural alteration that could not be detected by traditional Sanger sequencing. As a result, an analysis was performed using Multiplex Ligation–dependent Probe Amplification (MLPA), which documented a large heterozygous deletion involving exon 6 in both the proband and her mother, allowing us to define a mutational pattern consisting of p.Asn409Ser in trans with an exon deletion. This case report demonstrates the importance of an integrated diagnostic approach in the analysis of genetic diseases, in which clinical evaluation, biochemical tests and molecular techniques complement each other. The combination of family studies and methods complementary to Sanger sequencing, such as analyses for the detection of structural rearrangements, is essential for accurate genotypic characterization. This approach is essential not only for the correct interpretation of the genetic pattern, but also for providing appropriate genetic counselling and defining optimal clinical management of the patient.