Genetic variations and humoral immune responses to myelin oligodendroglia glycoprotein in adult phenotypes of X-linked adrenoleukodystrophy
Department of Neurology, University of Bonn, Sigmund-Freud-Str. 20, 53105, Bonn, Germany. Journal of Neuroimmunology
(Impact Factor: 2.47).
03/2003; 135(1-2):148-53. DOI: 10.1016/S0165-5728(02)00445-9
The lack of phenotype/genotype association in X-linked adrenoleukodystrophy (X-ALD) has prompted the search for disease modifying factors. We previously demonstrated increased serum antibody responses against myelin oligodendrocyte glycoprotein (MOG) in various clinical phenotypes of X-ALD allowing speculations that myelin specific humoral immune responses might be involved in phenotype generation of X-ALD. In the present study, we investigated the possible association of (1) a naturally occurring variable number tandem repeat (vntr) polymorphism (C allele) in the 3' flanking region of the interleukin-6 gene (IL-6), previously demonstrated to modify the course of Alzheimer's disease, systemic lupus erythematodes and Multiple Sclerosis (MS), (2) a tetranucleotide repeat polymorphism (TAAA)(n) in the 3' flanking region of the MOG gene and (3) HLA class II alleles with adult clinical phenotypes and serum antibody responses to MOG in 70 adult X-ALD patients. HLA class II alleles, (TAAA)(n) MOG gene polymorphisms, and IL-6 C allele were not associated with clinical phenotypes. Anti-MOG antibodies were detectable in 17/54 X-ALD patients (31.5%). Anti-MOG antibodies were associated with the 226 bp (TAAA)(n) MOG gene polymorphism but not with distinct clinical phenotypes.
Available from: Johannes Berger
- "Several candidate genes have been suggested as potential modifiers: peroxisomal ABC-half transporters related to ABCD1 (ABCD2, ABCD3); Very long chain fatty acid elongation (ELOVL1- 6 ) and activation system (ACSVL1 and BG1  ); genes related to initiation or maintenance of inflammation (CD1A-E, HLA-locus, TNFa, MOG     ) and cystathionine beta-synthase involved in the methionine metabolism  . It is tempting to speculate that more than one genetic variation might modulate the X-ALD phenotype. "
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ABSTRACT: Strikingly variable clinical phenotypes can be found in X-linked adrenoleukodystrophy (X-ALD) even with the same ABCD1 mutation. ABCD2 is the closest homolog to ABCD1. Since ABCD2 overexpression complements the loss of ABCD1 in vivo and in vitro, we have investigated the possible role of the ABCD2 gene locus as determinant of X-ALD phenotypes. Sequence and segregation analysis of the ABCD2 gene, in a large X-ALD family with different phenotypes disclosed that the identical ABCD2 alleles were inherited in brothers affected by mild (noncerebral) versus severe (childhood cerebral) X-ALD phenotypes. Moreover, two independent association studies of ABCD2 polymorphisms and clinical phenotypes showed an even allele distribution in different X-ALD phenotypes and controls. Based on these findings ABCD2 can be excluded as a major modifier locus for clinical diversity in X-ALD. These findings are of particular importance for the attempt of pharmacological induction of ABCD2 as a possible therapeutic approach in X-ALD.
Available from: Ali Fatemi
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ABSTRACT: The purpose of this article is to review and evaluate the new information about X-linked adrenoleukodystrophy that has been reported in 2002 and 2003.
X-linked adrenoleukodystrophy has two distinct neurological phenotypes: adrenomyeloneuropathy, a non-inflammatory axonopathy mostly in adults, and an intensely inflammatory cerebral myelinopathy mostly in children. The two forms often co-occur in the same family. Heterozygous women and the X-linked adrenoleukodystrophy mouse model often have the adrenomyeloneuropathy phenotype. More than 500 distinct mutations in the defective gene (ABCD1) have been identified, and except in one unique family, do not correlate with the phenotype. Bone marrow transplantation is beneficial in patients with early cerebral involvement. A panel of brain neuroimaging studies aids the selection of patients for bone marrow transplantation. Lorenzo's oil administered to neurologically asymptomatic boys who are less than 6 years old and have a normal magnetic resonance imaging scan appears to reduce the probability of developing neurological abnormalities later in life.
Progress has been achieved in the delineation of the phenotypes, pathogenesis, diagnosis and prevention of X-linked adrenoleukodystrophy, and therapies are emerging.
Available from: hmg.oxfordjournals.org
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ABSTRACT: Childhood cerebral adrenoleukodystrophy (CCER), adrenomyeloneuropathy (AMN) and AMN with cerebral demyelination (AMN-C) are the main phenotypic variants of X-linked adrenoleukodystrophy (ALD). It is caused by mutations in the ABCD1 gene encoding a half-size peroxisomal transporter that has to dimerize to become functional. The biochemical hallmark of ALD is the accumulation of very-long-chain fatty acids (VLCFA) in plasma and tissues. However, there is no correlation between the ALD phenotype and the ABCD1 gene mutations or the accumulation of VLCFA in plasma and fibroblast from ALD patients. The absence of genotype-phenotype correlation suggests the existence of modifier genes. To elucidate the mechanisms underlying the phenotypic variability of ALD, we studied the expression of ABCD1, three other peroxisomal transporter genes of the same family (ABCD2, ABCD3 and ABCD4) and two VLCFA synthetase genes (VLCS and BG1) involved in VLCFA metabolism, as well as the VLCFA concentrations in the normal white matter (WM) from ALD patients with CCER, AMN-C and AMN phenotypes. This study shows that: (1) ABCD1 gene mutations leading to truncated ALD protein are unlikely to cause variation in the ALD phenotype; (2) accumulation of saturated VLCFA in normal-appearing WM correlates with ALD phenotype and (3) expression of the ABCD4 and BG1, but not of the ABCD2, ABCD3 and VLCS genes, tends to be correlated with the severity of the disease, acting early in the pathogenesis of ALD.
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