The inherited metabolic disorders (IMD) are a heterogeneous group of genetic diseases, most of which involve a single gene mutation resulting in an enzyme defect. In the majority of cases, the enzyme defect leads to the accumulation of substrates that are toxic and/or interfere with normal cellular function. Often times, patients may appear normal at birth but during infancy begin to exhibit disease manifestations, frequently including progressive neurological deterioration due to absent or abnormal brain myelination. The ultimate result is death in later infancy or childhood.