A genetic disease that affects the brain and nerves which is caused by a recessive gene that causes abnormal lipid metabolism (it causes a deficiency in the enzyme beta-N-Acetylhexosaminidase A, which leads to an accumulation of ganglioside, which then damages and finally kills nerve cells). It occurs almost exclusively among people of eastern European Jewish ancestry (specifically, the Ashkenazi Jews). Neurologic problems appear early in an affected infant's development; deterioration starts around 3 months of age and the symptoms are obvious by 12 months of age. The disorder causes mental and physical retardation, blindness, convulsions and finally death when the child is between 2 and 5 years of age.