Spinal Muscular Atrophy (SMA) is a neuromuscular disease that results from production of a non-working form of the SMN (Survival of Motor Neuron) protein produced by the SMN gene. There are three types of SMA, numbered I, II, and III. Type I, also called Werdnig-Hoffman disease, is the most severe form and is almost always fatal before the age of 2 years. Hydroxyurea is a drug that has been shown to increase the amount of working SMN protein produced by certain cells in culture. The purpose of this trial is to test the safety and efficacy of hydroxyurea in treating Type I SMA patients.

Participation in our research will require regular visits to Stanford to be seen by our Primary Investigator over a period of at least 7 months (one month of observation before beginning six months of treatment with either hydroxyurea or placebo). At some of these visits, your son or daughter will have tests done to measure their muscle strength. We will also perform frequent blood work to monitor your child’s safety and monitor the amount of SMN protein and a certain kind of SMN RNA (the molecule that makes SMN protein).

Ages Eligible for Study:  up to  2 Years,  Genders Eligible for Study:  Both

Criteria

Inclusion Criteria:

• Clinical diagnosis of Type I SMA (never achieved independent sitting)
• Laboratory confirmation of homozygous deletion of the SMN1 gene (genetic diagnosis of SMA)
• Onset of the disease within the first 6 months of life
• Enrollment within 6 months of diagnosis
• Less than 2 years of age

Exclusion Criteria:

• Known hematological disorders (anemia, thrombocytopenia, etc.), severe systemic disorders or birth defects (heart, lung, kidneys, etc.), or neurological diseases other than SMA
• Severe birth asphyxia
• Participation in other clinical trials testing drugs against SMA at the time of enrollment into our study
• Patient is currently receiving full-time respiratory support