Plasmalogen Biosynthesis

Principle Of Method: Growing cells are incubated for 18h with [14C]-hexadecanol and [3H]-hexadecylglycerol. (The former molecule is a precursor for the peroxisomal part of the plasmalogen biosynthesis pathway and the latter for the microsomal part). The cells are harvested, lipids extracted and the extracts subjected to TLC. An acid hydrolysis step converts the plasmalogens to aldehydes which are separated by a further TLC run. The aldehyde band is scraped off and counted. Results are expressed as a ratio [3H]:[14C], a high value indicating deficiency of peroxisomal plasmalogen biosynthesis.

Uses And Limitations Of The Method: The method is used for further confirmation of diagnosis of the generalised peroxisomal disorders, Zellweger syndrome, neonatal adrenoleucodystrophy (NALD) and infantile Refsum disease (IRD). It may be particularly useful for some cases of NALD and IRD where other methods have not given conclusive results. It is also the method of choice for diagnosis of rhizomelic chondrodysplasia punctata (RCDP) because of the marked deficiency obtained for affected patients. It can also be used for prenatal diagnosis using cultured chorionic villi or amniotic cells. It cannot be used for direct analysis of cells or tissues, nor for heterozygote detection.

Specimen Requirements: Fibroblasts cultured from a skin biopsy are needed. Biopsy material should be collected aseptically into a sterile bottle containing tissue culture medium (available from the laboratory), and sent at room temperature to arrive at the laboratory within 24 hours.

Biopsies for tissue culture should not be frozen.

Fibroblast cultures established in other laboratories should be sent in plastic 25 cm2 flasks filled with medium.

The Laboratory Recommends Use Of A Courier Service Or Royal Mail Special Delivery For Sending All Specimens To The Laboratory.

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