A novel complex allele and two new point mutations in type 2 (acute neuronopathic) Gaucher disease

Gaucher disease, the most prevalent inherited sphingolipidosis, is characterized by lipid laden histiocytes in the spleen, liver and bone marrow sinusoids of affected individuals. It results from deleterious mutations in the functional gene of glucocerebrosidase (acid beta-glucosidase, EC. 3.2.1.45) and is transmitted as an autosomal recessive trait. Three clinical forms of Gaucher disease have been described: Type 1 non-neuronopathic, type 2 acute neuronopathic, and type 3 subacute neuronopathic. In this report, we describe the identification and characterization of three novel mutations from two patients who died with type 2 Gaucher disease. Two heterozygous missense point mutations, one at cDNA nucleotide 238A (E41L) and the other at cDNA nucleotide 508T (R131C) were identified, both in the context of a cDNA nucleotide 1448C (L444P) mutation in the second allele. One of these L444P mutations was identified as a novel complex allele resulting from a crossover involving the glucocerebrosidase functional gene and pseudogene beginning between genomic nucleotides 5689 and 5723 and extending through the rest of the coding sequence. Based on the recent identification and sequence analysis of the metaxin gene and pseudogene contiguous with the glucocerebrosidase pseudogene and functional gene respectively, we have developed a PCR-based method for the analysis of the origin and extent of this recombination.