Related Experiment Videos
Complementation analysis in patients with the clinical phenotype of a generalised peroxisomal disorder
1Division of Medical and Molecular Genetics, United Medical School, Guy's Hospital, London.
Insights
Generalised peroxisomal disorders (GPDs) like Zellweger syndrome involve peroxisome assembly failure. This study classifies GPD patients into complementation groups using biochemical and somatic cell hybridization methods.
Area of Science:
- Biochemistry
- Genetics
- Cell Biology
Background:
- Generalised peroxisomal disorders (GPDs) are a group of autosomal recessive diseases.
- These disorders result from a failure in the assembly of mature peroxisomes.
- Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), and infantile Refsum's disease (IRD) are key GPDs.
Purpose of the Study:
- To biochemically confirm diagnoses of GPDs in patients.
- To classify patients into complementation groups (CGs) using somatic cell hybridization.
- To investigate isolated peroxisomal beta-oxidation deficiencies.
Main Methods:
- Biochemical assays on skin fibroblasts: very long-chain fatty acids, plasmalogen biosynthesis, catalase solubility.
- Somatic cell hybridization experiments.
- Complementation analysis using beta-oxidation as a marker.
Main Results:
- Diagnoses confirmed for eight ZS and four IRD patients (GPD1-GPD12).
- Most GPD patients (six ZS, three IRD) belonged to CG-1.
- One patient (BOX-1) showed an isolated peroxisomal beta-oxidation deficiency, specifically of the bifunctional protein.
Conclusions:
- Biochemical and genetic classification of GPD patients is crucial for understanding disease mechanisms.
- Somatic cell hybridization effectively assigns patients to complementation groups.
- Identified distinct complementation groups for GPDs and isolated beta-oxidation defects.
Abstract:
The generalised peroxisomal disorders (GPDs) Zellweger syndrome (ZS), neonatal adrenoleucodystrophy (NALD), and infantile Refsum's disease (IRD) are autosomal recessive disorders associated with a failure to assemble mature peroxisomes. We confirmed the diagnosis of a GPD in eight ZS and four IRD patients (GPD1 to GPD12) biochemically by measuring very long chain fatty acids, plasmalogen biosynthesis, and catalase solubility in skin fibroblasts. One further patient (BOX-1) had the clinical phenotype of ZS, but biochemical investigations indicated an isolated deficiency of peroxisomal beta oxidation. To date a total of 10 complementation groups (CGs) for the GPDs and three further CGs for isolated beta oxidation deficiencies have been identified. Most GPD patients have been shown to belong to CG-1 (Baltimore classification); among the rarer groups, CG-4 and CG-8 predominate. We performed somatic cell hybridisation experiments on strains GPD-1 to GPD-12 using plasmalogen biosynthesis as a marker for correction and found that six ZS and three IRD patients, eight of whom were of UK origin, belonged to CG-1. Strain GPD-11, a patient of UK origin with an unusual biochemical phenotype, belonged to CG-8. Strains GPD-10 and GPD-12 were derived from ZS patients of Arabian and Pakistani origin and belonged to the rarer CGs 2 and 7, respectively. Furthermore, complementation analysis using beta oxidation as a marker showed that BOX-1 had an isolated deficiency of the bifunctional protein.