ABSTRACT. 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.

Keywords: Gaucher disease, glucocerebrosidase, mutation, pseudogene, complex allele.

Reprint requests to: Francis Y.M. Choy, Ph.D., Department of Biology, University of Victoria, P.O. Box 3020, Victoria, B.C. V8W 3N5, CANADA, phone: (250) 721-7095, fax: (250) 721-7120, email: fchoy@uvic.ca.

ABSTRACT. Sixty patients diagnosed with hereditary hemochromatosis with grade 3 or 4 hepatic iron overload and 18 patients diagnosed with hereditary hemochromatosis who had less than grade 3 hepatic iron overload were examined for the HFE gene mutations, 845A (C282Y) and 187G (H63D). Control samples were obtained from 109 randomly selected individuals. Fifty-six of 60 unrelated hereditary hemochromatosis patients (93%) with grade 3 or 4 hepatic iron deposition were homozygous for the C282Y mutation. Fourteen of the 18 hereditary hemochromatosis patients with <3+ iron deposition (76%) were homozygous for the C282Y mutation. Three of 8 patients who were heterozygous for the C282Y mutation were also heterozygous for the H63D mutation. Thirty-one of 109 control individuals were heterozygous for the C282Y mutation and 27 were heterozygous for the H63D mutation. Our finding that 93% of hereditary hemochromatosis patients who fulfil standard diagnostic criteria are homozygous for the C282Y mutation provides clear evidence that this mutation is strongly associated with hereditary hemochromatosis. The allele frequency of 14% for the C282Y mutation in our control population is the highest reported and supports the hypothesis of a Celtic origin for the hereditary hemochromatosis gene.

Keywords: Hemochromatosis, HFE, C282Y, H63D, Ireland.

Reprint requests to: John Crowe, M.D.,Ph.D., Liver Unit, Mater Misericordiae Hospital, Eccles Street, Dublin 7, IRELAND, phone: 353-1-8211337, fax: 353-1-8034770, e-mail: giunit@mater.ie.

ABSTRACT. The C282Y mutation in the HFE gene is the main mutation causing hemochromatosis, and C282Y frequencies have been reported for various European populations. The aim of this review is to compile the Y allele frequencies of the C282Y mutation for twenty European populations. The most elevated value (6.88%) is observed in residual Celtic populations in UK and France, in accordance to the hypothesis of Simon et al. concerning a Celtic origin of the hereditary hemochromatosis mutation.

Keywords: Hereditary hemochromatosis, C282Y mutation, Celtic origin.

Reprint requests to: Professor Gérard Lucotte, Laboratoire de Neurogénétique Moléculaire (Service de Neurologie), Hôpital Maison Blanche, 45 rue Cognacq-Jay, 51092 Reims Cédex, FRANCE, phone: 39727106, fax: 39727927.