Identification of the molecular defect in patients with peroxisomal mosaicism using a novel method involving culturing of cells at 40°C: Implications for other inborn errors of metabolism
✍ Scribed by Jeannette Gootjes; Frank Schmohl; Petra A.W. Mooijer; Conny Dekker; Hanna Mandel; Meral Topcu; Martina Huemer; M. von Schütz; Thorsten Marquardt; Jan A. Smeitink; Hans R. Waterham; Ronald J.A. Wanders
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 428 KB
- Volume
- 24
- Category
- Article
- ISSN
- 1059-7794
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✦ Synopsis
Communicated by Johannes Zschocke
The peroxisome biogenesis disorders (PBDs), which comprise Zellweger syndrome (ZS), neonatal adrenoleukodystrophy, and infantile Refsum disease (IRD), represent a spectrum of disease severity, with ZS being the most severe, and IRD the least severe disorder. The PBDs are caused by mutations in one of the at least 12 different PEX genes encoding proteins involved in the biogenesis of peroxisomes. We report the biochemical characteristics and molecular basis of a subset of atypical PBD patients. These patients were characterized by abnormal peroxisomal plasma metabolites, but otherwise normal to very mildly abnormal peroxisomal parameters in cultured skin fibroblasts, including a mosaic catalase immunofluorescence pattern in fibroblasts. Since this latter feature made standard complementation analysis impossible, we developed a novel complementation technique in which fibroblasts were cultured at 401C, which exacerbates the defect in peroxisome biogenesis. Using this method, we were able to assign eight patients to complementation group 3 (CG3), followed by the identification of a single homozygous c.959C4T (p.S320F) mutation in their PEX12 gene. We also investigated various peroxisomal biochemical parameters in fibroblasts at 301C, 371C, and 401C, and found that all parameters showed a temperature-dependent behavior. The principle of culturing cells at elevated temperatures to exacerbate the defect in peroxisome biogenesis, and thereby preventing certain mutations from being missed, may well have a much wider applicability for a range of different inborn errors of metabolism. Hum Mutat 24: 130-139, 2004.