Very long-chain fatty acids in Rett syndrome

Rett syndrome (RS), found exclusively in girls, is characterised by a global deceleration of psychomotor development, loss of acquired speech, loss of manual skills and subsequent deceleration of head growth. The cause of this syndrome is so far unknown. To date there are no biological markers for RS; clinical diagnostic criteria were proposed by the Rett Syndrome Diagnostic Criteria Work Group 1988. The first objective of this study was to assay the levels of very long-chain fatty acids (VLCFA), i.e. C22:0, C24:0, C26:0, by gas chromatography in sera of 30 girls with RS. The VLCFA levels in the studied group were lower than the reference range for healthy children and control group. VLCFA levels were again measured after 2 months of L-carnitine administration in the same groups. VLCFA levels had increased. It is possible that the low VLCFA levels have some relation to the lowered carnitine levels. It may be that low carnitine levels impede transportation to mitochondria, thus the oxidation of long-chain fatty acids is inhibited, and compensated to a certain extent by intensified beta-oxidation of VLCFA in the peroxisomal system. Raising carnitine levels could improve substrate delivery for mitochondrial beta-oxidation of long-chain fatty acids, thus reducing the use of VLCFA as substrates for beta-oxidation. We consider VLCFA to be secondary to the pathogenesis of RS, but the possible abnormalities in their levels may provide an insight into the development of this disease. Conclusion Very long-chain fatty acid and carnitine levels are decreased in Rett syndrome L-Carnitine administration increased very long-chain fatty acid levels in serum.