IDENTIFICATION AND EXPRESSION OF 8 NOVEL MUTATIONS AMONG NON-JEWISH PATIENTS WITH CANAVAN DISEASE

Canavan disease is inherited as an autosomal recessive trait that is c aused by the deficiency of aspartoacylase (ASPA). The majority of pati ents with Canavan disease are from an Ashkenazi Jewish background. Mut ations in ASPA that lead to loss of enzymatic activity have been ident ified, and E285A and Y231X are the two predominant mutations that acco unt for 97% of the mutant chromosomes in Ashkenazi Jewish patients. Th e current study was aimed at finding the molecular basis of Canavan di sease in 25 independent patients of non-Jewish background. Eight novel and three previously characterized mutations accounted for 80% (40/50 ) of mutant chromosomes. The A305E missense mutation accounted for 48% (24/50) of mutant chromosomes in patients of western European descent , while the two predominant Jewish mutations each accounted for a sing le mutant chromosome. The eight novel mutations identified included 1- and 4-bp deletions (32 Delta T and 876 Delta AGAA, respectively) and I16T, G27R, D114E, G123E, C152Y, and R168C missense mutations. The hom ozygous 32 Delta T deletion was identified in the only known patient o f African-American origin with Canavan disease. The heterozygosity for 876 Delta AGAA mutation was identified in three independent patients from England. Six single-base changes leading to missense mutations we re identified in patients from Turkey (D114E, R168C), The Netherlands (I16T), Germany (G27R), Ireland (C152Y), and Canada (G123E). A PCR-bas ed protocol is described that was used to introduce mutations in wild- type cDNA. In vitro expression of mutant cDNA clones demonstrated that all of these mutations led to a deficiency of ASPA and should therefo re result in Canavan disease.