A case of galactosialidosis with a homozygous Q49R point mutation

Infantile Galactosialidosis with Novel Mutation: An Early Presentation

Galactosialidosis (GS) is a rare lysosomal storage disorder. We reported here, the case of a 29-day-old boy who had increased body swelling, difficulty breathing, and petechiae on the trunk since birth. The antenatal history was unremarkable. Clinical laboratory findings included coarse facies, hepatosplenomegaly, gross ascites, thrombocytopenia, nephrotic range proteinuria, and bilateral hydronephrosis. The diagnostic challenge was resolved after genetic testing, which revealed GS with a novel homozygous c.1158dupA mutation.

Metabolic Cardiomyopathies and Cardiac Defects in Inherited Disorders of Carbohydrate Metabolism: A Systematic Review

Heart failure (HF) is a progressive chronic disease that remains a primary cause of death worldwide, affecting over 64 million patients. HF can be caused by cardiomyopathies and congenital cardiac defects with monogenic etiology. The number of genes and monogenic disorders linked to development of cardiac defects is constantly growing and includes inherited metabolic disorders (IMDs). Several IMDs affecting various metabolic pathways have been reported presenting cardiomyopathies and cardiac defects. Considering the pivotal role of sugar metabolism in cardiac tissue, including energy production, nucleic acid synthesis and glycosylation, it is not surprising that an increasing number of IMDs linked to carbohydrate metabolism are described with cardiac manifestations. In this systematic review, we offer a comprehensive overview of IMDs linked to carbohydrate metabolism presenting that present with cardiomyopathies, arrhythmogenic disorders and/or structural cardiac defects. We identified 58 IMDs presenting with cardiac complications: 3 defects of sugar/sugar-linked transporters (GLUT3, GLUT10, THTR1); 2 disorders of the pentose phosphate pathway (G6PDH, TALDO); 9 diseases of glycogen metabolism (GAA, GBE1, GDE, GYG1, GYS1, LAMP2, RBCK1, PRKAG2, G6PT1); 29 congenital disorders of glycosylation (ALG3, ALG6, ALG9, ALG12, ATP6V1A, ATP6V1E1, B3GALTL, B3GAT3, COG1, COG7, DOLK, DPM3, FKRP, FKTN, GMPPB, MPDU1, NPL, PGM1, PIGA, PIGL, PIGN, PIGO, PIGT, PIGV, PMM2, POMT1, POMT2, SRD5A3, XYLT2); 15 carbohydrate-linked lysosomal storage diseases (CTSA, GBA1, GLA, GLB1, HEXB, IDUA, IDS, SGSH, NAGLU, HGSNAT, GNS, GALNS, ARSB, GUSB, ARSK). With this systematic review we aim to raise awareness about the cardiac presentations in carbohydrate-linked IMDs and draw attention to carbohydrate-linked pathogenic mechanisms that may underlie cardiac complications.

A Turkish case of galactosialidosis with a new homozygous mutation in CTSA gene

Galactosialidosis is an autosamal reressive lysosomal storage disease caused by a combined deficiency of lysosomal β-galactosidase and neuraminidase, due to a primary defect in protective protein/cathepsin A. Three subtypes are recognized: the early infantile type, the late infantile type, and the juvenile/adult type. We report here a female patient with early infantile galactosialidosis who was born at 35 weeks of gestation. After birth she remained at the neonatal intensive care unit. Physical examination revealed, coarse facial features, hepatomegaly, cardiac murmur and diffuse hypotonia. The patient's mother had a past history of fetal hydrops history. The diagnosis of galactosialidosis was confirmed by decreased activity of β-galactosidase and undetectable neuraminidase activity in fibroblasts. Genetic examination revealed a new homozygous mutation (c.1284delG) in the CTSA gene.

Chemical chaperone treatment for galactosialidosis: Effect of NOEV on β-galactosidase activities in fibroblasts

INTRODUCTION

Galactosialidosis is a rare lysosomal storage disease caused by a combined deficiency of GM1 β-galactosidase (β-gal) and neuraminidase secondary to a defect of a lysosomal enzyme protective protein/cathepsin A (PPCA) and mutation in CTSA gene. Three subtypes are recognized: early infantile, late infantile, and juvenile/adult. There is no specific therapy for patients with galactosialidosis at this time.

OBJECTIVES

The aim of this study was to determine the chaperone effect of N-octyl-4-epi-β-valienamine (NOEV) on β-gal proteins in skin fibroblasts of PPCA-deficit patients.

METHODS

β-Gal and neuraminidase activities were measured for the diagnosis of the patients with galactosialidosis. Western blotting for PPCA protein and direct sequencing for CTSA gene were performed. Cultured skin fibroblast were treated with NOEV.

RESULTS

We report four novel patients with galactosialidosis: one had the early infantile form and the other three had the juvenile/adult form. We found that NOEV stabilized β-gal activity in lysate from cultured skin fibroblasts from these patients. Treatment with NOEV significantly enhanced β-gal activity in cultured skin fibroblasts in the absence of PPCA.

CONCLUSIONS

Our results indicate the possibility that NOEV chaperone therapy might have a beneficial effect, at least in part, for patients with galactosialidosis.

Galactosialidosis: review and analysis of CTSA gene mutations

Background

Mutations in the CTSA gene, that encodes the protective protein/cathepsin A or PPCA, lead to the secondary deficiency of β-galactosidase (GLB1) and neuraminidase 1 (NEU1), causing the lysosomal storage disorder galactosialidosis (GS). Few clinical cases of GS have been reported in the literature, the majority of them belonging to the juvenile/adult group of patients.

Methods

The correct nomenclature of mutations for this gene is discussed through the analysis of the three PPCA/CTSA isoforms available in the GenBank database. Phenotype-genotype correlation has been assessed by computational analysis and review of previously reported single amino acid substitutions.

Results

We report the clinical and mutational analyses of four cases with the rare infantile form of GS. We identified three novel nucleotide changes, two of them resulting in the missense mutations, c.347A>G (p.His116Arg), c.775T>C (p.Cys259Arg), and the third, c.1216C>T, resulting in the p.Gln406* stop codon, a type of mutation identified for the first time in GS. An Italian founder effect of the c.114delG mutation can be suggested according to the origin of the only three patients carrying this mutation reported here and in the literature.

Conclusions

In early reports mutations nomenclature was selected according to all CTSA isoforms (three different isoforms), thus generating a lot of confusion. In order to assist physicians in the interpretation of detected mutations, we mark the correct nomenclature for CTSA mutations. The complexity of pathology caused by the multifunctions of CTSA, and the very low numbers of mutations (only 23 overall) in relation to the length of the CTSA gene are discussed.

In addition, the in silico functional predictions of all reported missense mutations allowed us to closely predict the early infantile, late infantile and juvenile phenotypes, also disclosing different degrees of severity in the juvenile phenotype.