Canavan disease is an autosomal recessive progressive leukodystrophy that often leads to death in the first decade of life. Leukodystrophies are a group of rare genetic disorders that affect the central nervous system by disrupting the growth or maintenance of the myelin sheath that insulates nerve cells. Canavan disease is caused by a deficiency of the enzyme, aspartoacylase (ASPA). Canavan disease is more common in the Ashkenazi Jewish population where about 1 in 40 persons is estimated to be a carrier. This blood test identifies carriers and affected individuals for four mutations associated with Caravan disease: E285A, Y231X, 433-2A>G, and A305E. Couples who are both carriers have a one in four risk of having a child with Canavan disease. A305E is the Canavan mutation found among individuals of non-Ashkenazi Jewish ancestry. This test detects 98% of mutations responsible for Canavan disease in Ashkenazi Jews, and 60% of mutations in non-Jewish Caucasians.