Identification of a novel recombinant allele in three unrelated Italian Gaucher patients: Implications for prognosis and genetic counseling

Gaucher disease (GD) results from deleterious mutations in the glucocerebrosidase gene. The relatively high frequency of some of these, especially at cDNA nucleotide 1226G (N370S) and at cDNA nucleotide 1448C (L444P), has led to the development of rapid screening techniques that can sometimes be misleading. In this report, we describe a novel rearrangement between the glucocerebrosidase gene and its pseudogene, identified as a consequence of a discrepancy between the genotype, homozygous for the common 1226G mutation, of an Italian patient with type 1 Gaucher disease, and the absence of the 1226G allele in her daughter. Additional investigations went on to reveal a novel recombinant allele beginning in intron 6 and extending through the rest of the coding sequence. Italian GD patients found homozygous for a specific mutation or with one or both alleles still unknown were further investigated and the novel recombinant allele was identified in an adult type 1 patient previously genotyped 1226G/1226G and in a young patient with an unknown genotype. The detection of this allele in three unrelated GD patients originating from the same geographic area in central Italy suggested a founder effect. This study emphasizes the implications of an accurate genotyping for the prognostic value of glucocerebrosidase genotype and reliable genetic counseling. (C) 2000 Academic Press.