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Molecular analysis of acid ceramidase deficiency in patients with Farber disease
Author(s) -
Bär Julia,
Linke Thomas,
Ferlinz Klaus,
Neumann Ulrich,
Schuchman Edward H.,
Sandhoff Konrad
Publication year - 2001
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.5
Subject(s) - sphingolipid , biology , exon , ceramide , biochemistry , point mutation , mutation , microbiology and biotechnology , exon skipping , gene , alternative splicing , apoptosis
Farber disease is a rare, autosomal recessively inherited sphingolipid storage disorder due to the deficient activity of lysosomal acid ceramidase, leading to the accumulation of ceramide in cells and tissues. Here we report the identification of six novel mutations in the acid ceramidase gene causing Farber disease: three point mutations resulting in single amino acid substitutions, one intronic splice site mutation resulting in exon skipping, and two point mutations also leading to occasional or complete exon skipping. Of interest, these latter two mutations occurred in adjacent nucleotides and led to abnormal splicing of the same exon. Expression of the mutated acid ceramidase cDNAs in COS‐1 cells and subsequent determination of acid ceramidase residual enzyme activity demonstrated that each of these mutations was the direct cause of the acid ceramidase deficiency in the respective patients. In contrast, two known polymorphisms had no effect on acid ceramidase activity. Metabolic labeling studies in fibroblasts of four patients showed that even though acid ceramidase precursor protein was synthesized in these individuals, rapid proteolysis of the mutated, mature acid ceramidase occurred within the lysosome. Hum Mutat 17:199–209, 2001. © 2001 Wiley‐Liss, Inc.