Tay-Sachs Disease Presenting as Refractory Epilepsy with Autistic Regression Secondary to a Novel Mutation in HEXA Gene
To the Editor: Tay-Sachs disease (TSD) is an autosomal recessive lysosomal storage disorder due to deficiency of beta hexosaminidase A enzyme. It is caused by mutations in HEXA gene . The prevalence of TSD in general population is 1 in 3,20,000 . We report a child with TSD presenting as autistic regression and refractory epilepsy due to novel mutation.
In the current case, the possible differential diagnosis considered were, Neuronal ceroid lipofuscinosis (NCL), Lafora body disease, mitochondrial disorders and gangliosidosis. Enzyme assay for NCL1 and 2 were normal. Axillary skin biopsy for negative inclusion bodies ruled out Lafora body disease. Mitochondrial disorders were ruled out as serum lactate and tandem mass spectrometry was normal. Enzyme assay showed deficiency of Beta Hexosaminidase A level; hence diagnosed as TSD.
The usual presentation of TSD is developmental delay followed by regression in the later part of the infancy. Examination usually shows large head with cherry red spot in the fundus. In this child regression started after 3 y of age predominantly the social interaction with refractory epilepsy, normal head size and without cherry red spot. There are more than 130 mutations identified in the HEXA gene . This phenotype has not been described previously in the literature. In the genetic testing, the novel mutation was found. In conclusion TSD should be considered as a differential diagnosis in a patient who present as autistic regression with epilepsy.
VKG: Revised and approved the manuscript for important intellectual content and will act as guarantor of the paper; VMS: Diagnosis, management and writing the manuscript; MB: Conducted laboratory tests and analyzed the data; AB: Supervision of the work and revision of manuscript.
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