The natural history of classic galactosemia: lessons from the GalNet registry.

BACKGROUND: Classic galactosemia is a rare inborn error of carbohydrate metabolism, caused by a severe deficiency of the enzyme galactose-1-phosphate uridylyltransferase (GALT). A galactose-restricted diet has proven to be very effective to treat the neonatal life-threatening manifestations and has been the cornerstone of treatment for this severe disease. However, burdensome complications occur despite a lifelong diet. For rare diseases, a patient disease specific registry is fundamental to monitor the lifespan pathology and to evaluate the safety and efficacy of potential therapies. In 2014, the international Galactosemias Network (GalNet) developed a web-based patient registry for this disease, the GalNet Registry. The aim was to delineate the natural history of classic galactosemia based on a large dataset of patients. METHODS: Observational data derived from 15 countries and 32 centers including 509 patients were acquired between December 2014 and July 2018. RESULTS: Most affected patients experienced neonatal manifestations (79.8%) and despite following a diet developed brain impairments (85.0%), primary ovarian insufficiency (79.7%) and a diminished bone mineral density (26.5%). Newborn screening, age at onset of dietary treatment, strictness of the galactose-restricted diet, p.Gln188Arg mutation and GALT enzyme activity influenced the clinical picture. Detection by newborn screening and commencement of diet in the first week of life were associated with a more favorable outcome. A homozygous p.Gln188Arg mutation, GALT enzyme activity of ≤ 1% and strict galactose restriction were associated with a less favorable outcome. CONCLUSION: This study describes the natural history of classic galactosemia based on the hitherto largest data set.

CAV3 gene sequence variations: National Genome Database and clinics.

INTRODUCTION: Caveolinopathies are a group of untreatable, degenerative muscle diseases associated with caveolin 3 (CAV3) gene mutations. OBJECTIVES: The goal of this study was to characterize the role of the CAV3 gene in patients with limb-girdle muscular dystrophy, hyperCKemia, cardiomyopathies, as well as utilization of the National Genome Database in clinical applications. MATERIALS AND METHODS: We sequenced the coding region and exon/intron boundaries of CAV3 gene in 81 neuromuscular disorder patients, a sample group from the National Genome Database, consisting of 97 individuals with cardiomyopathies, and also random selection of 100 persons. Immunohistochemical staining of muscle biopsy was performed to verify findings in one case, as the setup for the project was to use less invasive molecular biology methods. RESULTS: We identified three novel sequence variations (c.183C>G, p.S61R; c.220C>A, p.R74S; c.220C>T, p.R74C) and found evidence that one was associated with hypercreatine kinase-emia. Two previously reported mutations in families with limb-girdle muscular dystrophy were found. No mutations were identified in the cohort of patients with cardiomyopathies. DISCUSSION: CAV3 gene encodes muscle-specific protein with dominant negative type of missense mutations in it causing various phenotypes. Our study confirmed CAV3 gene involvement in neuromuscular disorders, but found no evidence in the group of patients with cardiomyopathies. Persons included in the National Genome Database could be screened for late onset Mendelian diseases.