Utility of measuring very long-chain fatty-acyl carnitines in dried blood spots for newborn screening of X-linked Adrenoleukodystrophy.

We measured C24:0 and C26:0-carnitines in dried blood spots by flow injection analysis-tandem mass spectrometry method to evaluate whether they can be used as markers for newborn screening of X-linked Adrenoleukodystrophy (X-ALD). We found that C26:0-carnitine was 95.1% and 44.7% sensitive for identifying male X-ALD cases and heterozygous females, respectively. False negatives were found for C24:0-carnitine (11/82) and C26:0-carnitine (4/82). We conclude that C24:0 and C26:0-carnitines may not be reliable markers for X-ALD screening.

Deciphering the modifiers for phenotypic variability of X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD), an inborn error of peroxisomal ß-oxidation, is caused by defects in the ATP Binding Cassette Subfamily D Member 1 (ABCD1) gene. X-ALD patients may be asymptomatic or present with several clinical phenotypes varying from severe to mild, severe cerebral adrenoleuko-dystrophy to mild adrenomyeloneuropathy (AMN). Although most female heterozygotes present with AMN-like symptoms after 60 years of age, occasional cases of females with the cerebral form have been reported. Phenotypic variability has been described within the same kindreds and even among monozygotic twins. There is no association between the nature of ABCD1 mutation and the clinical phenotypes, and the molecular basis of phenotypic variability in X-ALD is yet to be resolved. Various genetic, epigenetic, and environmental influences are speculated to modify the disease onset and severity. In this review, we summarize the observations made in various studies investigating the potential modifying factors regulating the clinical manifestation of X-ALD, which could help understand the pathogenesis of the disease and develop suitable therapeutic strategies.