Tay-Sachs disease in an Arab family due to c.78G>A HEXA nonsense mutation encoding a p.W26X early truncation enzyme peptide

Unusual case of Juvenile Tay-Sachs disease

Tay-Sachs disease (TSD) is a type 1 gangliosidosis (GM2) and caused by hexosaminidase A deficiency resulting in abnormal sphingolipid metabolism and deposition of precursors in different organs. It is a progressive neurodegenerative disorder transmitted in an autosomal-recessive manner. There is an accumulation of GM2 in neurocytes and retinal ganglions which result in progressive loss of neurological function and formation of the cherry-red spot which is the hallmark of TSD. We report the first case of juvenile TSD from Pakistan in a child with death of an older sibling without the diagnosis.

Presentation of central precocious puberty in two patients with Tay-Sachs disease

Tay-Sachs disease is an autosomal recessive type of lysosomal storage disorder. The disease is very rare in Turkey, with an incidence of 0.54/100,000. The clinical manifestations of Tay-Sachs disease include progressive developmental delay, seizures, deafness, blindness, spasticity, and dystonia, which are caused by the accumulation of gangliosides in the central nervous system. To date, only one case indicating the association between Tay-Sachs disease and central precocious puberty has been reported. Although the mechanism of this association is not clear, it is thought to be due to ganglioside accumulation in the central nervous system or the inhibition of the hypothalamic inhibiting pathway. Herein, we report two patients with genetically proven Tay-Sachs disease who developed central precocious puberty during follow-up. Pubertal development in patients affected by Tay-Sachs disease should be carefully assessed.

The first family with Tay-Sachs disease in Cyprus: Genetic analysis reveals a nonsense (c.78G>A) and a silent (c.1305C>T) mutation and allows preimplantation genetic diagnosis

Tay-Sachs disease (TSD) is a recessively inherited neurodegenerative disorder caused by mutations in the HEXA gene resulting in β-hexosaminidase A (HEX A) deficiency and neuronal accumulation of GM2 ganglioside. We describe the first patient with Tay-Sachs disease in the Cypriot population, a juvenile case which presented with developmental regression at the age of five. The diagnosis was confirmed by measurement of HEXA activity in plasma, peripheral leucocytes and fibroblasts. Sequencing the HEXA gene resulted in the identification of two previously described mutations: the nonsense mutation c.78G>A (p.Trp26X) and the silent mutation c.1305C>T (p.=). The silent mutation was reported once before in a juvenile TSD patient of West Indian origin with an unusually mild phenotype. The presence of this mutation in another juvenile TSD patient provides further evidence that it is a disease-causing mutation. Successful preimplantation genetic diagnosis (PGD) and prenatal follow-up were provided to the couple.

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First patient with Tay-Sachs disease (TSD) in the Cypriot population

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Silent mutation is a disease causing mutation.

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Successful preimplantation genetic diagnosis

Three novel mutations in Iranian patients with Tay-Sachs disease

BACKGROUND

Tay-Sachs disease (TSD), or GM2 gangliosidosis, is a lethal autosomal recessive neurodegenerative disorder, which is caused by a deficiency of beta-hexosaminidase A (HEXA), resulting in lysosomal accumulation of GM2 ganglioside. The aim of this study was to identify the TSD-causing mutations in an Iranian population.

METHODS

In this study, we examined 31 patients for TSD-causing mutations using PCR, followed by restriction enzyme digestion.

RESULTS

Molecular genetics analysis of DNA from 23 patients of TSD revealed mutations that has been previously reported, including four-base duplications c.1274_1277dupTATC in exon 11 and IVS2+1G>A, deletion TTAGGCAAGGGC in exon 10 as well as a few novel mutations, including C331G, which altered Gln>Glu in HEXB, A>G, T>C, and p.R510X in exon 14, which predicted a termination codon or nonsense mutation.

CONCLUSION

In conclusion, with the discovery of these novel mutations, the genotypic spectrum of Iranian patients with TSD disease has been extended and could facilitate definition of disease-related mutations.