We previously reported that in childhood adrenoleukodystrophy (C-ALD) and adrenomyeloneuropathy (AMN), the peroxisomal fl-oxidation system for very long chain (>C22) fatty acids is defective. To further define the defect in these two forms of X chromosome-linked ALD, we examined the oxidation of [1-14C]lignoceric acid (n-tetracosanoic acid, C24:0) and [1-'4C]lignoceroyl-CoA (substrates for the first and second steps of f8-oxidation, respectively). The oxidation rates of lignoceric acid in C-ALD and AMN were 43% and 36% of control values, respectively, whereas the oxidation rate of lignoceroyl-CoA was 109% (C-ALD) and 106% (AMN) of control values, respectively. On the other hand, the oxidation rates of palmitic acid (n-hexadecanoic acid) and palmitoyl-CoA in C-ALD and AMN were similar to the control values. These results suggest that lignoceroyl-CoA ligase activity may be impaired in C-ALD and AMN. To identify the specific enzymatic deficiency and its subcellular localization in C-ALD and AMN, we established a modified procedure for the subcellular fractionation of cultured skin fibroblasts. Determination of acyl-CoA ligase activities provided direct evidence that lignoceroyl-CoA ligase is deficient in peroxisomes while it is normal in mitochondria and microsomes. Moreover, the normal oxidation of lignoceroyl-CoA as compared with the deficient oxidation of lignoceric acid in isolated peroxisomes also supports the conclusion that peroxisomal lignoceroyl-CoA ligase is impaired in both C-ALD and AMN. Palmitoyl-CoA ligase activity was found to be normal in peroxisomes as well as in mitochondria and microsomes. This normal peroxisomal palmitoyl-CoA ligase activity as compared with the deficient activity of lignoceroyl-CoA ligase in C-ALD and AMN suggests the presence of two separate acyl-CoA ligases for palmitic and lignoceric acids in peroxisomes. These data clearly demonstrate that the pathognomonic accumulation of very long chain fatty acids in C-ALD and AMN is due to a deficiency of peroxisomal very long chain (lignoceric acid) acyl-CoA ligase.The peroxisomal disorders represent a newly characterized group of inherited diseases (1, 2). In the adrenoleukodystrophies (ALD), three forms are recognized: childhood ALD (C-ALD; X chromosome-linked), adult ALD [adrenomyeloneuropathy (AMN); X chromosome-linked], and neonatal ALD (autosomal recessive). C-ALD is the most common form (3, 4) and usually appears between the ages of 4 and 8 years. It is characterized by central nervous system demyelination and adrenal cortical insufficiency. Death occurs during the first or second decade. AMN occurs mainly in adults, progresses more slowly, and affects the adrenal cortex, spinal cord, and peripheral nerves (5). The occurrence of both C-ALD and AMN within the same kindred suggests that these forms of ALD are different clinical manifestations of the same mutation (4). The identification of an identical biochemical defect in both would confirm this assumption. The neonatal form of ALD is a severe disorder that is evident in...

We have previously reported that the peroxisomal β‐oxidation system for very long chain fatty acids is defective in X‐linked childhood adrenoleukodystrophy [(1984) Proc. Natl. Acad. Sci. USA 81, 4203‐4207]. In order to elucidate the specific enzyme defect, we examined the oxidation of [1‐14C]lignoceric acid, [1‐14C]lignoceroyl‐CoA and (1‐14C)‐labelled α,β‐unsaturated lignoceroyl‐CoA (substrates for the 1st, 2nd, and 3rd steps of the β‐oxidation cycle, respectively). These studies suggest that the pathognomonic accumulation of very long chain fatty acids in X‐linked childhood ALD may be due to the defective activity of peroxisomal very long chain (lignoceroyl‐CoA) acyl‐CoA ligase.

No abstract

BackgroundMost previous studies of chromosomal mosaicism in IVF embryos were performed by fluorescence in situ hybridization (FISH) methods. While there are reports implicating chromosome aneuploidy in implantation failure following transfer and pregnancy loss by spontaneous miscarriage, the significance of mosaicism for the developmental potential of growing embryos is unknown. However, the low prevalence of chromosomal mosaicism in chorionic villus sampling and amniotic fluid specimens suggests the presence of selection against mosaic embryos for implantation and early pregnancy. The absence of evidence for selective allocation of abnormal cells to the trophectoderm (TE) of mosaic blastocysts permits these cells to be a good proxy for embryonic mosaicism detection by chromosomal microarrays (CMA). The purpose of this study was to establish the limits of detection and the prevalence of chromosome mosaicism in day 5/6 human embryos using CMA with TE biopsies.ResultsFrom reconstitution experiments we established log2 ratio thresholds for mosaicism detection. These studies indicated that chromosomal mosaicism at levels as low as between 25-37% can be consistently identified. Follow-up studies by FISH on non-transferred abnormal embryos confirmed the diagnostic accuracy of CMA testing. The number of cells in a TE biopsy can influence mosaicism detection.ConclusionsChromosomal microarrays can detect mosaicism in TE biopsies when present at levels as low as between 25-37% and the prevalence of day 5/6 blastocysts which were mosaic and had no other abnormalities reached 15% among a cohort of 551 embryos examined. Validated protocols for establishing detection thresholds for mosaicism are important to reduce the likelihood of transferring abnormal embryos.

We report on a mildly abnormal 5-year-old girl with seizures, psychomotor retardation, and areas of hyperpigmentation who had a supernumerary marker chromosome in fibroblasts which was identified as an i(5p). To our knowledge, this is the first reported case of tetrasomy 5p. She shares in common some, but not all, manifestations of the dup (5p) syndrome. Cytogenetic analysis of relatives showed that the phenotypically apparently normal mother, maternal grandmother, and a brother of the proband also had a marker chromosome in their lymphocytes which was unrelated to the i(5p).