The number of controls was insufficient compared to case.

GM2 gangliosidosis is an autosomal recessive subtype of Lysosomal Storage Diseases in which, Hexosaminidase A-B deficiency is caused by HEXA-B gene. HEXA deficiency is seen in Tay sachs and HEXB deficiency causes Sandhoff disease.

Infantile forms of Sandhoff and Tay sachs are often lethal and management of the patients is supportive including nutrition, hydration, seizure control and management of respiratory problems. Recent studies have suggested new methods of treatment, such as enzyme replacement therapy, bone marrow transplantation and substrate reduction therapy.

The first drug used in SRT was Miglustat. It was introduced in 1980 as an anti HIV agent and later, it was registered under the trademark of Zavesca in 2009 and was used in treatment of Gaucher and Niemann-Pick disease. Zavesca passes blood brain barrier, so causes reduction of cholesterol and glycosphingolipids CNS neurons and relief of neurologic manifestations. Improvements were seen in oculomotor function, cognition, swallowing, motor disturbances and psychological problems after treatment with Zavesca. No effect has been proved on visceral involvement. Weight loss during first year of treatment, diarrhea and dyspepsia are seen as side effects.

Studies on SRT in lysosomal storage disease have different results. Some show improvements in manifestations of Gausche, Sandhoff & Tay sachs disease, while others show no valuable benefit for this method of treatment.

Finding an effective treatment for these chronic diseases can improve quality of life for the patients and their families, and also reduce costs for healthcare services. The controversy persists and more studies are needed for judgment. So this study is done to evaluate the effect of Miglustat therapy in Sandhoff and Tay sachs disease, and is believed to help for further studies in this field.

This study is a case- control, open label clinical trial. Patients are all registered with diagnosis of Sandhoff and Tay sachs, and recruited at children's medical center Tehran-IRAN. Diagnosis is confirmed by enzyme level and genetic tests. Case group receive Miglustat therapy for 1 year and frequently assessed. Patients in control group are also assessed for 1 year without receiving Miglustat.

Patients are evaluated for neurologic examination, seizure, nasogastric tube insertion, aspiration pneumonia and quality of life at the beginning of study and every 3 months. Miglustat is considered as an Orphan drug so clinical trials about this drug are designed small and adjusted to limited population.

Variables in neurologic examination are Muscle tone, Muscular atrophy and contracture. motor function is scored according to "Gross Motor Function Classification System" (GMFCS) and quality of life is assessed by Infant Toddle Quality Of Life (ITQOL) questionnaire, with confirmed validity and stability.

Data gathered during frequent visits is registered in check lists and analyzed with SPSS version 18. Quantitative variables express with mean and standard deviation and qualitative variables with frequency and percentile. Analysis of variance for repeated measurements (ANOVA) and nonparametric freedman are tests using for comparisons of Outcomes. Sample size is calculated by formula for clinical trials with repeated measures.

Miglustat is FDA approved for Gaucher and Niemann pick diseases. All patients fill the informed consent and the nature of the study is explained to them. The information of participants is kept confidential. They are informed about side effects of the drug. If any cases at any time decides to exclude themselves from the study they are free to do so.

Inclusion Criteria:

• Clinically and enzymatically suspected infants of Sandhoff (SD)/Tay-Sachs (TSD) diseases followed confirmation by molecular study.

Exclusion Criteria:

• Renal impairment
• Loss of follow up
• Other systemic diseases
• Concomitant drug therapy which may affect neurological system function