MOLECULAR ANALYSIS OF GAUCHER DISEASE - SCREENING OF PATIENTS IN THE MONTREAL QUEBEC REGION

Gaucher disease, the most prevalent lysosomal storage disease, is an autosomal recessive sphingolipidosis resulting from deficient glucocerebrosidase activity. Genomic DNA of the structural gene of glucocerebrosidase from normal individuals and fifteen unrelated patients with the three clinical forms of Gaucher disease from the Montreal/Quebec region were amplified by the polymerase chain reaction technique. Allele-specific oligonucleotide dot blot hybridization and restriction fragment length polymorphism were used to screen for five of the mutations [mutations 120, 370, 415, 444 (Nci), and 463] in exons 5, 9, and 10 of glucocerebrosidase gene. It was noted that all of the patients had at least one of the known mutant alleles. However, 9 patients (9/15 = 60%) had an unknown allele. Mutation 370 in exon 9 was present in the heteroallelic form in eight out of the nine patients with type 1 Gaucher disease, but was present in none of the six patients with type 2 or type 3 Gaucher disease. The Nci mutation in exon 10 was present in the heteroallelic form in three patients with type 1 Gaucher disease and in either the heteroallelic or homoallelic form in all of the six patients with type 2 or type 3 Gaucher disease. The 415/Nci mutations were found in a mildly affected 29-year-old patient with type 1 Gaucher disease, as well as in an infant with the type 2 form. These findings demonstrate the clinical and molecular genetic heterogeneities of Gaucher disease, the presence of unknown Gaucher allele(s) in most (60%) of the patients surveyed, and the occasional inexplicable lack of phenotype-genotype correlation among some patients. It also suggests that other genetic factor(s) may be implicated in determining the phenotypic expression of Gaucher disease.