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Fabry disease (FD) is an X-linked genetic disease due to pathogenic variants in GLA. The phenotype varies depending on the GLA variant, alpha-galactosidase residual activity, patient's age and gender and, for females, X chromosome inactivation. Over 1000 variants have been identified, many through screening protocols more susceptible to disclose non-pathogenic variants or variants of unknown significance (VUS). This, together with the non-specificity of some FD symptoms, challenges physicians attempting to interpret GLA variants. The traditional way to interpreting pathogenicity is based on a combined approach using allele frequencies, genomic databases, global and disease-specific clinical databases, and in silico tools proposed by the American College of Medical Genetics and Genomics. Here, a panel of FD specialists convened to study how expertise may compare with the traditional approach. Several GLA VUS, highly controversial in the literature (p.Ser126Gly, p.Ala143Thr, p.Asp313Tyr), were re-analyzed through reviews of patients' charts. The same was done for pathogenic GLA variants with some specificities. Our data suggest that input of geneticists and physicians with wide expertise in disease phenotypes, prevalence, inheritance, biomarkers, alleles frequencies, disease-specific databases, and literature greatly contribute to a more accurate interpretation of the pathogenicity of variants, bringing a significant additional value over the traditional approach., (© 2021 The Authors. Clinical Genetics published by John Wiley & Sons Ltd.)

Fabry disease (FD), a rare X-linked disease, can be treated with bi-monthly infusion of enzyme replacement therapy (ERT) to replace deficient α-galactosidase A (AGAL-A). ERT reduces symptoms, improves quality of life (QoL), and improves clinical signs and biochemical markers. ERT initiation in childhood could slow or stop progressive organ damage. Preventative treatment of FD from childhood is thought to avoid organ damage in later life, prompting a French expert working group to collaborate and produce recommendations for treating and monitoring children with FD. Organ involvement should be assessed by age 5 for asymptomatic boys (age 12-15 for asymptomatic girls), and immediately for children diagnosed via symptoms. The renal, cardiac, nervous and gastrointestinal systems should be assessed, as well as bone, skin, eyes, hearing, and QoL. The plasma biomarker globotriaosylsphingosine is also useful. ERT should be considered for symptomatic boys and girls with neuropathic pain, pathological albuminuria (≥3 mg/mmol creatinine), severe GI involvement and abdominal pain or cardiac involvement. ERT should be considered for asymptomatic boys from the age of 7. Organ involvement should be treated as needed. Early diagnosis and management of FD represents a promising strategy to reduce organ damage, morbidity and premature mortality in adulthood., (© 2019 The Authors. Clinical Genetics published by John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Fabry disease (FD) is an X-linked genetic disorder caused by the deficient activity of lysosomal α-galactosidase (α-Gal). While males are usually severely affected, clinical presentation in female patients may be more variable ranging from asymptomatic to, occasionally, as severely affected as male patients. The aim of this study was to evaluate the existence of skewed X-chromosome inactivation (XCI) in females with FD, its concordance between tissues, and its contribution to the phenotype. Fifty-six females with FD were enrolled. Clinical and biological work-up included two global scores [Mainz Severity Score Index (MSSI) and DS3], cardiac magnetic resonance imaging, measured glomerular filtration rate, and measurement of α-Gal activity. XCI was analyzed in four tissues using DNA methylation studies. Skewed XCI was found in 29% of the study population. A correlation was found in XCI patterns between blood and the other analyzed tissues although some punctual variability was detected. Significant differences in residual α-Gal levels, severity scores, progression of cardiomyopathy and deterioration of kidney function, depending on the direction and degree of skewing of XCI were evidenced. XCI significantly impacts the phenotype and natural history of FD in females., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Gaucher's disease (GD) is one of the most prevalent lysosomal storage disorders (LSDs) and a rare genetic disease for which specific therapy is now available. GD is an autosomal, recessive, inborn error of glycosphingolipid metabolism, due to a deficiency in the enzyme acid beta-glucosidase. Partial deficiency of acid beta-glucosidase is associated with parenchymal disease of the liver, spleen, and bone marrow with concomitant anemia and thrombocytopenia in non-neuronopathic, type 1 GD. Severe deficiency of glucocerebrosidase caused by severe mutations is additionally associated with neurological manifestations in the less common type 2 and type 3 GD subtypes. Outside of the Ashkenazi Jewish community, a high molecular diversity is observed. Clarification of genotype/phenotype relationship and the identification of modifier loci that impact on GD phenotypes remains a critical area for research. Enzyme replacement therapy (ERT) is proven to be safe and effective in the treatment of type 1 GD, establishing imiglucerase as the current standard of care. Amelioration of hepatosplenomegaly and of hematological manifestations is usually apparent within 6-12 months, whereas the bone disease responds more slowly. ERT cannot reverse the neurological deficits in type 2 or type 3 GD. Small molecule inhibitors of glucosylceramide synthase are being developed for substrate reduction therapy. Other potential therapeutic options such as chaperon-mediated enzyme enhancement therapy and gene therapy are being explored.

Fabry disease (FD, OMIM 301500) is an X-linked disorder of glycosphingolipid metabolism resulting from the deficient activity of alpha-galactosidase A, a lysosomal acid hydrolase, leading to progressive lysosomal accumulation of incompletely metabolized neutral glycosphingolipids. Cardiac involvement is frequent. The objective of this study was to characterize the cardiac abnormalities in male patients affected with classic Fabry disease and define the context in which the clinicians were able to make the diagnosis. Clinical evaluation, laboratory tests, electrocardiography (ECG) and echocardiography were performed in 20 hemizygous men (mean age 39 years, range 12-65 years). The context of diagnosis was obtained by review of patients' charts. Left ventricular hypertrophy (LVH) and/or concentric remodeling were found in 12 patients (60%). Structural changes in mitral and aortic valves were found in 25% and 10% of cases, respectively. The sensitivity of the ECG Romhilt-Estes score for LVH was high (80%). Short PR interval (40%), ST segment abnormalities and conduction delay were frequent on ECG. Left ventricular mass index, ECG scores for LVH and systolic pulmonary pressure correlated positively with age. There was no relation between classic vascular risk factors and coronary artery disease, transient ischemic attack (TIA) or stroke. Diagnosis of Fabry disease was frequently suggested by nephrologists, dermatologists or geneticists. Echocardiograph and ECG abnormalities are frequently observed in patients with Fabry disease. Cardiologists should be aware of the diagnosis of Fabry disease in patients presenting with LVH, concentric remodeling, mitral and aortic valve thickening on echocardiography, short PR interval and conduction defects on ECG.

Fabry disease (FD) is an X-linked recessive inborn error of glycosphingolipid metabolism. Among clinical symptoms, maculopapular skin lesions, known as angiokeratoma, most often appear on the lower abdomen, scrotum, and thighs, with a tendency toward bilateral symmetry. A 30-year-old male patient was referred to us for evaluation of a complex vascular and cutaneous malformation. Skin examination showed numerous angiokeratoma, which had developed only on the right part of the body, with a sharp delineation in the midline of the trunk. The diagnosis of FD was confirmed by demonstration of a decreased alpha-galactosidase A activity, and the patient was shown to be hemizygote for a missense mutation (R342Q) in the alpha-galactosidase A gene (GLA). This mutation was also demonstrated in DNA extracted from fibroblast cultures established from both affected and unaffected skin areas, thus excluding the hypothesis of somatic mosaicism or revertant mosaicism. Interestingly, the diagnosis of Klippel-Trénaunay-Weber syndrome (KTWS) was also made, through clinical and radiological investigations. This is the first report on the association between FD and KTWS. Karyotype analysis was normal. It is likely that the mixed vascular malformations of KTWS affecting capillary and venous systems have contributed to the unusual angiokeratoma distribution pattern observed in the patient.