OBJECTIVE: To explore the genetic basis for a girl featuring epilepsy, developmental delay and regression. METHODS: Clinical data of the patient was collected. Activities of hexosaminidase A (Hex A) and hexosaminidase A&B (Hex A&B) in blood leukocytes were determined by using a fluorometric assay. Peripheral blood samples were collected from the proband and six members from her pedigree. Following extraction of genomic DNA, whole exome sequencing was carried out. Candidate variants were verified by Sanger sequencing. RESULTS: Enzymatic studies of the proband have shown reduced plasma Hex A and Hex A&B activities. Genetic testing revealed that she has carried c.1260_1263del and c.1601G>C heterozygous compound variants of the HEXB gene. Her mother, brother and sister were heterozygous carriers of c.1260_1263del, while her father, mother, three brothers and sister did not carry the c.1601G>C variant, suggesting that it has a de novo origin. Increased eosinophils were discovered upon cytological examination of peripheral blood and bone marrow samples. CONCLUSION The compound heterozygous variants of c.1260_1263del and c.1601G>C of the HEXB gene probably underlay the Sandhoff disease in this child. Eosinophilia may be noted in infantile Sandhoff disease.
Child ; Eosinophilia/genetics* ; Female ; Genetic Testing ; Hexosaminidase A/genetics* ; Hexosaminidase B/genetics* ; Humans ; Male ; Mutation ; Pedigree ; Sandhoff Disease/genetics*

A boy, aged 5 years, attended the hospital due to progressive psychomotor regression for 2.5 years. Motor function regression was the main manifestation in the early stage, and brain MRI and whole-exome sequencing (WES) of the family showed no abnormalities. After the age of 4 years and 9 months, the boy developed cognitive function regression, and brain MRI showed cerebellar atrophy. The reanalysis of WES results revealed a compound heterozygous mutation, [NM_000520, c.784C>T(p.His262Tyr]), c.1412C>T(p.Pro471Leu)], in the HEXA gene. The enzyme activity detection showed a significant reduction in the level of β-hexosaminidase encoded by this gene. The boy was diagnosed with juvenile Tay-Sachs disease (TSD). TSD has strong clinical heterogeneity, and cerebellar atrophy may be an important clue for the diagnosis of juvenile TSD. The reanalysis of genetic data when appropriate based on disease evolution may improve the positive rate of WES.
Atrophy ; Humans ; Magnetic Resonance Imaging ; Male ; Mutation ; Tay-Sachs Disease/genetics*

OBJECTIVE: To detect potential mutations of HEXB gene in an infant with Sandhoff disease (SD). METHODS: Genomic DNA was extracted from peripheral blood sample of the infant. All coding exons (exons 1 to 14) and splicing sites of the HEXB gene were subjected to PCR amplification and direct sequencing.PubMed Protein BLAST system was employed to analyze cross-species conservation of the mutant amino acid. PubMed BLAST CD-search was performed to identify functional domains destroyed by thecandidate mutations. Impact of the mutations was analyzed with software including PolyPhen-2, Mutation Taster and SIFT. Whole-exome sequencing was carried out to identify additional mutations. RESULTS: The infant was found to carry compound heterozygous mutations c.1652G>A(p.Cys551Tyr) and c.1389C>G (p.Tyr463*) of the HEXB gene. The c.1389C>G (p.Tyr463*) mutation may lead to destruction of two functional domains in β subunit of the Hex protein. The c.1652G>A(p.Cys551Tyr) mutation, unreported previously,was predicted to be probably damaging by Bioinformatic analysis. CONCLUSION Compound heterozygous mutations c.1652G>A(p.Cys551Tyr) and c.1389C>G (p.Tyr463*) in the HEXB gene probably underlie the disease in this patient.
DNA Mutational Analysis ; Exons ; Heterozygote ; Humans ; Infant ; Mutation ; Polymerase Chain Reaction ; Sandhoff Disease ; genetics ; beta-Hexosaminidase beta Chain ; genetics

Infants with Sandhoff disease typically appear normal until 3–6 months of age. As the disease progresses, they present with symptoms such as loss of motor skills, exaggerated startle response to loud noise, seizures, visual loss, and paralysis. We encountered a rare case of a 22-month-old girl with Sandhoff disease characterized by progressive motor weakness and dysphagia, who initially showed signs of aspiration at 20 months of age. The major problems related to dysphagia were oromotor dysfunction and abnormal feeding posture. Within 3 months of identification of difficulty in swallowing, the patient showed a significant decrease in food intake, with rapid deterioration of nutritional status. We report our case with a review of the literature.
Deglutition Disorders ; Deglutition* ; Eating ; Female ; Humans ; Infant ; Motor Skills ; Noise ; Nutritional Status ; Paralysis ; Posture ; Reflex, Startle ; Sandhoff Disease* ; Seizures

Tay-Sachs disease (TSD) is an autosomal recessive neurodegenerative disorder caused by mutations in the HEXA gene resulting in a deficiency of β-hexosaminidase A (HEX A) enzyme. To our knowledge, TSD has never been reported in Thai population. We describe the first case of classic infantile TSD in a 2-year-old Thai boy who presented with first episode of seizure and neuroregression since 9 months of age. Hyperacusis, progressive macrocephaly and macular cherry red spots were also detected during examination. Brain MRI revealed hyperintensity in the basal ganglion on T1-weighted and partial corpus callosum agenesis. Measurement of β-hexosaminidase activity in the patient leukocytes showed low total β-hexosaminidase (62.6 normal 801+/-190 nmol/mg protein/hr) and low %HEX A (7.57 normal 55-72%HEX A) activity compatible with TSD. Mutation analysis of the HEXA gene revealed compound heterozygous of a novel frameshift mutation (c.1207delG or p.E403SfsX20) in exon 11 which was inherited from the mother and a previously described missense mutation (c.1510C>T or p.R504C) in exon 13 which was inherited from the father, respectively. Conclusion. We report a clinical, biochemical and molecular analysis in the first case of genetically confirmed classic infantile TSD in Thailand.
Tay-Sachs Disease

OBJECTIVETo explore the clinical features and molecular mutation of HEXB gene in a case with juvenile Sandhoff disease.

METHODWe retrospectively reviewed the clinical, neuroimaging and biochemical findings in this Chinese child with juvenile Sandhoff disease. Hexosaminidase A and hexosaminidase A & B activities were measured in blood leukocytes by fluorometric assay. HEXB gene molecular analysis was performed by PCR and direct sequencing.

RESULTThe 9-year-old boy was admitted for psychomotor regression. He presented slowly progressive gait disorder and dysarthria during the last three years. Cranial MRI revealed a marked cerebellar atrophy with normal intensity in the thalamus and basal ganglia. Brain MRS showed normal in the thalamus and basal ganglia. Hexosaminidase A was 69.5 (mg·h) [normal controls 150-360 nmol/(mg·h)], hexosaminidase A & B activity was 119 nmol/(mg·h)[normal controls 600-3 500 nmol/(mg·h)], confirming the diagnosis of Sandhoff disease. The patient was a compound heterozygote for a novel deletion mutation c.1404delT (p. P468P fsX62) and a reported mutation c.1509-26G>A.

CONCLUSIONThe clinical features of juvenile Sandhoff disease include ataxia, dysarthria and cerebellar atrophy. The enzyme assay and molecular analysis of HEXB gene can confirm the diagnosis of Sandhoff disease. The novel mutation c.1404delT(p. P468P fsX62) is a disease-related mutation.

Brain ; diagnostic imaging ; pathology ; Cerebellar Ataxia ; diagnosis ; enzymology ; genetics ; Child ; DNA Mutational Analysis ; Heterozygote ; Hexosaminidase A ; blood ; metabolism ; Hexosaminidase B ; blood ; metabolism ; Humans ; Leukocytes ; enzymology ; Magnetic Resonance Imaging ; Male ; Mutation ; Radiography ; Retrospective Studies ; Sandhoff Disease ; diagnosis ; enzymology ; genetics ; beta-Hexosaminidase beta Chain ; genetics

OBJECTIVETo investigate the phenotype and genotype of a Chinese boy and his family affected by infantile Sandhoff disease.

METHODSThe proband, a boy, was the first child born to a non-consanguineous couple. He showed startle reaction after birth and progressive psychomotor regression from the age of 8 months. From the age of 16 months, he presented seizures. When he was admitted at 17 months old, severe mental retardation and weakness were observed. Fundus examination revealed bilateral cherry-red spots in the macula and optic atrophy. Cranial MRI revealed abnormal signals in the thalamus, basal ganglia and white matter. Enzymatic assay and genetic testing were performed for the diagnosis. His mother visited us at 18 weeks of pregnancy seeking for prenatal diagnosis. HEXB gene diagnosis to the fetus was performed by direct sequencing.

RESULTSSignificant deficient total β-hexosaminidase (A and B) activity in peripheral leucocytes of the patient (0.0 nmol/h/mg compared with normal control, 41.9 to 135.1 nmol/h/mg) supported the diagnosis of Sandhoff disease. On his HEXB gene, two mutations were found. c.1645G-A (p.G549R) was novel. c.IVS7-48T was a reported mutation. Now, the patient was 2 years and 3 months old, with progressive general failure, severe epilepsy, blindness and hypermyotonia. Subsequently, the mother visited us at 18 weeks of pregnancy seeking for prenatal diagnosis. HEXB gene analysis of the amniocytes was performed by direct sequencing. Both of the two mutations were not detected from cultured amniocytes. The result revealed that the fetus was not affected by Sandhoff disease. A healthy girl, the sibling of the proband, was born in term. Postnatal enzyme analysis and genetic analysis of the cord blood cells confirmed the prenatal diagnosis.

CONCLUSIONOne novel mutation on HEXB gene was identified. Prenatal diagnosis to the fetus of this family was performed by amniocytes gene analysis.

Adult ; Amniotic Fluid ; cytology ; Child, Preschool ; DNA Mutational Analysis ; Female ; Genetic Testing ; Humans ; Male ; Mutation ; Pregnancy ; Prenatal Diagnosis ; Sandhoff Disease ; diagnosis ; genetics ; beta-Hexosaminidase beta Chain ; genetics

Tay-Sachs Disease (TSD), the most common form of GM(2) gangliosidosis, is an autosomal recessive inborn lysosomal glycosphingolipid storage disease which is resulted from the mutations that affect the alpha-subunit locus on chromosome 15 and cause a severe deficiency of hexosaminidase A. It is characterized by normal motor development in the first few months of life, followed by progressive weakness and loss of motor skills beginning around 6 months of life. Neurodegeneration is relentless and manifested as relentless motor and mental deterioration, beginning with motor incoordination, mental obtundation leading to muscular flaccidity, blindness, and increasing dementia, with death occurring by the age of 4 or 5 years. We report a successful anesthetic management in a patient with Tay-Sachs Diseases for tracheostomy and feeding gastrostomy.
Ataxia ; Blindness ; Chromosomes, Human, Pair 15 ; Dementia ; Gangliosidoses ; Gastrostomy ; Hexosaminidase A ; Hexosaminidases ; Humans ; Motor Skills ; Muscle Hypotonia ; Tay-Sachs Disease* ; Tracheostomy

Sandhoff disease is a rare autosomal recessive metabolic disease presenting bilateral optic atrophy and a cherry red spot in the macula. This case report presents the characteristics of a patient with Sandhoff disease as assessed by ophthalmic, neuroimaging, and laboratory procedures. Ophthalmologic examination revealed that the patient could not fixate her eyes on objects nor follow moving targets. A pale optic disc and a cherry red spot in the macula were seen in both eyes. Low signal intensity at the thalamus and high signal intensity at the cerebral white matter were noted in a T2-weighted brain MR image. A lysosomal enzyme assay using fibroblasts showed the marked reduction of both total beta-hexosaminidases, A and B. Based on the above clinical manifestations and laboratory findings, we diagnosed the patient as having Sandhoff disease.
Atrophy ; Cerebral Cortex/*pathology ; Child, Preschool ; Female ; Humans ; Isoenzymes/deficiency ; Lipid Metabolism, Inborn Errors/*diagnosis/enzymology ; Magnetic Resonance Imaging ; Ocular Motility Disorders/*diagnosis ; Optic Disk/*pathology ; Retinal Diseases/*diagnosis ; Sandhoff Disease/*diagnosis/enzymology ; Thalamus/pathology ; beta-N-Acetylhexosaminidase/deficiency

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*