GM1 gangliosidosis is an autosomal recessive disorder caused by galactosidase beta1 (GLB1) gene variants which affect the activity of β-galactosidase (GLB). GLB dysfunction causes abnormalities in the degradation of GM1 and its accumulation in lysosome. This article reports the clinical and genetic features of a child with GM1 gangliosidosis. The girl, aged 2 years and 5 months, was referred to the hospital due to motor developmental regression for more than one year. Physical examination showed binocular deflection and horizontal nystagmus, but no abnormality was found on fundoscopy. The girl had increased muscular tone of the extremities, limitation of motion of the elbow, knee, and ankle joints, and hyperactive patellar tendon reflex. Blood biochemical examination showed a significant increase in aspartate aminotransferase. The 24-hour electroencephalographic monitoring detected frequent seizure attacks and diffuse θ wave activity, especially in the right hemisphere. Head magnetic resonance imaging showed thinner white matter in the periventricular region and diffuse high T2WI signal with unclear boundary. Three-dimensional reconstruction of white matter fiber tracts by diffusion tensor imaging showed smaller and thinner white matter fiber tracts, especially in the right hemisphere. Genetic analysis showed that the girl had compound heterozygous mutations of c.446C>T (p.Ser149Phe) and c.101T>C (p.Ile34Thr) in the GLB1 gene from her parents, among which c.101T>C (p.Ile34Thr) had not been reported in the literatures. The girl was finally diagnosed with GM1 gangliosidosis. Her conditions were not improved after antiepileptic treatment and rehabilitation training for 2 months.
Diffusion Tensor Imaging ; Female ; Gangliosidosis, GM1 ; genetics ; Humans ; Infant ; Mutation ; Virulence ; beta-Galactosidase ; genetics

OBJECTIVE: To explore the genetic cause for a child with growth retardation by next generation sequencing (NGS). METHODS: Clinical data of the patient was collected. Peripheral venous blood samples were taken from the neonate and his parents. Targeted capturing and NGS were carried out to detect mutations of genes associated with inborn errors of metabolism. Suspected mutations were validated by Sanger sequencing. RESULTS: The 15-month-old female patient was admitted to hospital for growth retardation for 4 months. Hypomyelination was found upon cranium MRI. Genetic testing revealed two novel insertional mutations in the GLB1 gene in the patient, namely c.2006-2007insT and c.475-476 insGGTCC. CONCLUSION The c.2006-2007insT and c.475-476 insGGTCC mutations of the GLB1 gene probably underlie the GM1 gangliosidosis resulting in the growth retardation in the child.
Female ; Gangliosidosis, GM1 ; genetics ; Humans ; Infant ; Infant, Newborn ; Mutation ; Pedigree ; beta-Galactosidase ; genetics

OBJECTIVE: To explore the genotype-phenotype correlation of a case with GM1-gangliosidosis caused by compound heterogenic variants in GLB1. METHODS: Genomic DNA was extracted from peripheral blood samples from the patient and her parents. Trio-based whole-exome sequencing (WES) was performed for the family and suspected mutation was verified by Sanger sequencing. RESULTS: The proband, a 2-year-3-month old Chinese girl, presented with psychomotor deterioration, absent speech, intellectual disabilities and behavior problem. Trio-based WES has identified compound heterozygosity for 2 variants in the GLB1 gene: NM_000404.2:c.1343A>T, p.Asp448Val and c.1064A>C, p.Gln355Pro (GRCh37/hg19),which was inherited from the mother and father, respectively. Homozygous or compound heterozygous pathogenic variants in GLB1, encoding β-galactosidase, are responsible for GM1-gangliosidosis,an autosomal recessive lysosomal storage disorder characterized by variable degrees of neurodegeneration and skeletal abnormalities. The p.Asp448Val variant has been classified as pathogenic for GM1 gangliosidosis in medical literatures for the reason that functional studies demonstrated that expression of the p.Asp448Val variant in COS-1 cells resulted in no detectable β-galactosidase activity compared to wild type GLB1. The p.Gln355Pro variant has not been reported in literatures or database. The variant is highly conserved residue (PM1), and was not found in either the Genome Aggregation Database or the 1000 Genomes Project (PM2) and was predicted to have a deleterious effect on the gene product by multiple in silico prediction tools (PP3). Next, the β-galactosidase activity of the patient's peripheral blood leukocytes was determined by fluorescent method. The result was 0.0 nmol/mg. It showed that the p.Gln355Pro variant also resulted in loss of β-galactosidase activity, thus the variant was classified into clinical pathogenic variant. CONCLUSION Our study expands the mutational spectrum of the GLB1 gene and provides genetic counseling for the family.
Asians/genetics* ; China ; Female ; G(M1) Ganglioside ; Gangliosidosis, GM1/genetics* ; Humans ; Mutation ; beta-Galactosidase/genetics*

Sphingolipidoses are a subgroup of lysosomal storage disorders. They are characterized by relentless progressive storage in affected organs and concomitant functional impairments. No overall screening procedure for these disorders is available. Their course and appearance, however, are usually characteristic and, together with relevant technical procedures such as magnetic resonance imaging (MRI), clinical neurophysiology, ophthalmologic examination, etc., a provisional diagnosis can be made, after which enzymatic diagnosis can close the gap in the diagnostic process. Subgroups of sphingolipidoses are grouped together, such as disorders with prominent hepatosplenomegaly (Niemann-Pick A, B and Gaucher disease) and disorders with central and peripheral demyelination (metachromic leukodystrophy and Krabbe disease). Farber disease and Fabry disease are unique in themselves. The last decade has seen hopeful progress in therapeutic strategies, especially for Gaucher disease. Therefore, emphasis of this review has been placed on these new developments.
Demyelinating Diseases ; Diagnosis ; Fabry Disease ; Farber Lipogranulomatosis ; Gangliosidoses, GM2 ; Gangliosidosis, GM1 ; Gaucher Disease ; Hope ; Leukodystrophy, Globoid Cell ; Magnetic Resonance Imaging ; Mass Screening ; Neurophysiology ; Niemann-Pick Diseases ; Sphingolipidoses*

Galactosialidosis is a lysosomal storage disease associated with a combined deficiency of beta-galactosidase and alpha-neuraminidase, secondary to a defect of another lysosomal protective protein. It is a neurodegenerative disorder clinically characterized by psychomotor deterioration, cerebellar ataxia, coarse facies, generalized bony deformity and organomegaly. Three phenotypic subtype are recognized:early infantile, late infantile and juvenile/adult type. We report a 13 months old boy with a late infantile galactosialidosis. He was presented with progressive mental regression and motor disturbance and observed cherry red spot, hearing loss, moderate dysostosis multiplex and vacuolated lymphocytes in peripheral blood. He showed only beta-galactosidase deficiency in the lymphocytes and was diagnosed as GM1-gangliosidosis type 1. However, further studies revealed the possible defect of alpha-neuraminidase suggesting that he was a case of galactosialidosis which was mimicking GM1-gangliosidosis type 1.
beta-Galactosidase ; Cathepsin A ; Cerebellar Ataxia ; Congenital Abnormalities ; Dysostoses ; Facies ; Gangliosidosis, GM1 ; Hearing Loss ; Humans ; Infant ; Lymphocytes ; Lysosomal Storage Diseases ; Male ; Mucolipidoses ; Neurodegenerative Diseases ; Prunus