ABCMdb

ABCD1 p.Ala626Thr

Predicted by SNAP2:	C: D (85%), D: D (95%), E: D (95%), F: D (95%), G: D (91%), H: D (95%), I: D (85%), K: D (95%), L: D (91%), M: D (91%), N: D (95%), P: D (95%), Q: D (95%), R: D (95%), S: D (91%), T: D (91%), V: D (85%), W: D (95%), Y: D (95%),
Predicted by PROVEAN:	C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, S: D, T: D, V: D, W: D, Y: D,

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[hide] Live cell FRET microscopy: homo- and heterodimeriz... J Biol Chem. 2007 Sep 14;282(37):26997-7005. Epub 2007 Jul 3. Hillebrand M, Verrier SE, Ohlenbusch A, Schafer A, Soling HD, Wouters FS, Gartner J
Live cell FRET microscopy: homo- and heterodimerization of two human peroxisomal ABC transporters, the adrenoleukodystrophy protein (ALDP, ABCD1) and PMP70 (ABCD3).
J Biol Chem. 2007 Sep 14;282(37):26997-7005. Epub 2007 Jul 3., [PMID:17609205]

Abstract [show]
The adrenoleukodystrophy protein (ALDP) and the 70-kDa peroxisomal membrane protein (PMP70) are half-ATP-binding cassette (ABC) transporters in the mammalian peroxisome membrane. Mutations in the gene encoding ALDP result in a devastating neurodegenerative disorder, X-linked adrenoleukodystrophy (X-ALD) that is associated with elevated levels of very long chain fatty acids because of impaired peroxisomal beta-oxidation. The interactions of peroxisomal ABC transporters, their role in the peroxisomal membrane, and their functions in disease pathogenesis are poorly understood. Studies on ABC transporters revealed that half-transporters have to dimerize to gain functionality. So far, conflicting observations are described for ALDP. By the use of in vitro methods (yeast two-hybrid and immunoprecipitation assays) on the one hand, it was shown that ALDP can form homodimers as well as heterodimers with PMP70 and ALDR, while on the other hand, it was demonstrated that ALDP and PMP70 exclusively homodimerize. To circumvent the problems of artificial interactions due to biochemical sample preparation in vitro, we investigated protein-protein interaction of ALDP in its physiological environment by FRET microscopy in intact living cells. The statistical relevance of FRET data was determined in two different ways using probability distribution shift analysis and Kolmogorov-Smirnov statistics. We demonstrate in vivo that ALDP and PMP70 form homodimers as well as ALDP/PMP70 heterodimers where ALDP homodimers predominate. Using C-terminal deletion constructs of ALDP, we demonstrate that the last 87 C-terminal amino acids harbor the most important protein domain mediating these interactions, and that the N-terminal transmembrane region of ALDP has an additional stabilization effect on ALDP homodimers. Loss of ALDP homo- or heterodimerization is highly relevant for understanding the disease mechanisms of X-ALD.

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244 They transfected fibroblasts from an X-ALD patient (A626T) with an ALDP construct carrying a myc epitope replacing amino acids 693-745. Login to comment
242 They transfected fibroblasts from an X-ALD patient (A626T) with an ALDP construct carrying a myc epitope replacing amino acids 693-745. Login to comment
243 They transfected fibroblasts from an X-ALD patient (A626T) with an ALDP construct carrying a myc epitope replacing amino acids 693-745. Login to comment

[hide] ABCD1 mutations and the X-linked adrenoleukodystro... Hum Mutat. 2001 Dec;18(6):499-515. Kemp S, Pujol A, Waterham HR, van Geel BM, Boehm CD, Raymond GV, Cutting GR, Wanders RJ, Moser HW
ABCD1 mutations and the X-linked adrenoleukodystrophy mutation database: role in diagnosis and clinical correlations.
Hum Mutat. 2001 Dec;18(6):499-515., [PMID:11748843]

Abstract [show]
X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene, which encodes a peroxisomal ABC half-transporter (ALDP) involved in the import of very long-chain fatty acids (VLCFA) into the peroxisome. The disease is characterized by a striking and unpredictable variation in phenotypic expression. Phenotypes include the rapidly progressive childhood cerebral form (CCALD), the milder adult form, adrenomyeloneuropathy (AMN), and variants without neurologic involvement. There is no apparent correlation between genotype and phenotype. In males, unambiguous diagnosis can be achieved by demonstration of elevated levels of VLCFA in plasma. In 15 to 20% of obligate heterozygotes, however, test results are false-negative. Therefore, mutation analysis is the only reliable method for the identification of heterozygotes. Since most X-ALD kindreds have a unique mutation, a great number of mutations have been identified in the ABCD1 gene in the last seven years. In order to catalog and facilitate the analysis of these mutations, we have established a mutation database for X-ALD ( http://www.x-ald.nl). In this review we report a detailed analysis of all 406 X-ALD mutations currently included in the database. Also, we present 47 novel mutations. In addition, we review the various X-ALD phenotypes, the different diagnostic tools, and the need for extended family screening for the identification of new patients.

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174 P560S 7 1678C>T n.d. # P560L 7 1679C>T Reduced P560L 7 1679C>T Reduced fs I588 7 1765delC n.d. # R591P 7 1772G>C Absent S606L 8 1817C>T Present E609K 8 1825G>A Absent E609K 8 1825G>A Absent R617C 8 1849C>T Absent R617H 8 1850G>A Absent R617H 8 1850G>A Absent A626T 9 1876G>A Absent A626T 9 1876G>A Absent A626D 9 1877C>A n.d. # E630G 9 1889A>G n.d. # C631Y 9 1892G>A n.d. # T632I 9 1895C>T n.d. # V635M 9 1903G>A n.d. # L654P 9 1961T>C Absent # R660W 9 1978C>T Absent fs L663 9 1988insT n.d. # fs L663 IVS 9 IVS9+1g>a n.d. # fs L663 IVS 9 IVS9-1g>a n.d. # H667D 10 1999C>G Absent # T668I 10 2003C>T Absent # T693M 10 2078C>T Present # exon1-5del 1-5 n.d. # The 47 mutations marked with a # are novel unique mutations reported for the first time in this paper. Login to comment

[hide] Adrenoleukodystrophy-related protein can compensat... Hum Mol Genet. 1999 May;8(5):907-13. Netik A, Forss-Petter S, Holzinger A, Molzer B, Unterrainer G, Berger J
Adrenoleukodystrophy-related protein can compensate functionally for adrenoleukodystrophy protein deficiency (X-ALD): implications for therapy.
Hum Mol Genet. 1999 May;8(5):907-13., [PMID:10196381]

Abstract [show]
Inherited defects in the peroxisomal ATP-binding cassette (ABC) transporter adrenoleukodystrophy protein (ALDP) lead to the lethal peroxisomal disorder X-linked adrenoleukodystrophy (X-ALD), for which no efficient treatment has been established so far. Three other peroxisomal ABC transporters currently are known: adrenoleukodystrophy-related protein (ALDRP), 70 kDa peroxisomal membrane protein (PMP70) and PMP70- related protein. By using transient and stable overexpression of human cDNAs encoding ALDP and its closest relative ALDRP, we could restore the impaired peroxisomal beta-oxidation in fibroblasts of X-ALD patients. The pathognomonic accumulation of very long chain fatty acids could also be prevented by overexpression of ALDRP in immortalized X-ALD cells. Immunofluorescence analysis demonstrated that the functional replacement of ALDP by ALDRP was not due to stabilization of the mutated ALDP itself. Moreover, we were able to restore the peroxisomal beta-oxidation defect in the liver of ALDP-deficient mice by stimulation of ALDRP and PMP70 gene expression through a dietary treatment with the peroxisome proliferator fenofibrate. These results suggest that a correction of the biochemical defect in X-ALD could be possible by drug-induced overexpression or ectopic expression of ALDRP.

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28 To investigate the influence of expression of ALDP and ALDRP on β-oxidation in an ALDP/ALDRP-deficient system, we used SV40-transformed skin fibroblasts from an X-ALD patient with the missense mutation A626T, which lack the punctate immunoreactive staining pattern characteristic for ALDP (23). Login to comment
113 11 with mutation A626T in ref. Login to comment
112 11 with mutation A626T in ref. Login to comment
29 To investigate the influence of expression of ALDP and ALDRP on b2;-oxidation in an ALDP/ALDRP-deficient system, we used SV40-transformed skin fibroblasts from an X-ALD patient with the missense mutation A626T, which lack the punctate immunoreactive staining pattern characteristic for ALDP (23). Login to comment

[hide] Co-expression of mutated and normal adrenoleukodys... Hum Mol Genet. 2000 Nov 1;9(18):2609-16. Unterrainer G, Molzer B, Forss-Petter S, Berger J
Co-expression of mutated and normal adrenoleukodystrophy protein reduces protein function: implications for gene therapy of X-linked adrenoleukodystrophy.
Hum Mol Genet. 2000 Nov 1;9(18):2609-16., [PMID:11063720]

Abstract [show]
Inherited defects in the X-chromosomal adrenoleukodystrophy (ALD; ABCD1) gene are the genetic cause of the severe neurodegenerative disorder X-linked adrenoleukodystrophy (X-ALD). Biochemically the accumulation of very long-chain fatty acids, caused by impaired peroxisomal beta-oxidation, is the pathognomonic characteristic of the disease. Due to the X-chromosomal inheritance of X-ALD no data are available to clarify the question whether mutated adrenoleukodystrophy proteins (ALDPs) can negatively influence normal ALDP function. Here we show that restoration of beta-oxidation in X-ALD fibroblasts following transient transfection with normal ALD cDNA is more effective in ALDP-deficient fibroblasts compared with fibroblasts expressing normal amounts of mutated ALDP. Furthermore, we utilized the HeLa Tet-on system to construct a stable HeLa cell line expressing a constant level of endogenous ALDP and doxycycline-inducible levels of mutated ALDP. The induction was doxycycline dosage-dependent and the ALDP correctly localized. Interestingly, although mutated ALDP increased >6-fold in a dosage-dependent manner the total amount of ALDP (mutated and normal) remained approximately even as demonstrated by western blot and flow cytometric analyses. Thus, apparently mutated and normal ALDP compete for integration into a limited number of sites in the peroxisomal membrane. Consequently, increased amounts of mutated ALDP resulted in decreased peroxisomal beta-oxidation and accumulation of very long-chain fatty acids. These findings have direct implications on future gene therapy approaches for treatment of X-ALD, since in some patients a non-functional endogenous protein could act in a dominant negative way or displace the introduced, normal protein.

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43 In accordance with these data, transient transfection of ALDP-deficient fibroblasts (A626T) with normal ALD cDNA resulted in restoration of β- oxidation. Login to comment
51 Transient transfection of normal ALD cDNA into X-ALD fibroblast cell lines: A626T lack detectable ALDP, whereas N148S, D194H and S312C cell lines produce stable, mutated ALDP. Login to comment
162 SV40-transformed X-ALD fibroblasts lacking ALDP (mutation A626T) were kindly provided by Drs Smith and Braiterman (Baltimore, MD) (32). Login to comment

[hide] X-linked adrenoleukodystrophy: ABCD1 de novo mutat... Mol Genet Metab. 2011 Sep-Oct;104(1-2):160-6. Epub 2011 Jun 22. Wang Y, Busin R, Reeves C, Bezman L, Raymond G, Toomer CJ, Watkins PA, Snowden A, Moser A, Naidu S, Bibat G, Hewson S, Tam K, Clarke JT, Charnas L, Stetten G, Karczeski B, Cutting G, Steinberg S
X-linked adrenoleukodystrophy: ABCD1 de novo mutations and mosaicism.
Mol Genet Metab. 2011 Sep-Oct;104(1-2):160-6. Epub 2011 Jun 22., [PMID:21700483]

Abstract [show]
X-linked adrenoleukodystrophy (X-ALD) is a progressive peroxisomal disorder affecting adrenal glands, testes and myelin stability that is caused by mutations in the ABCD1 (NM_000033) gene. Males with X-ALD may be diagnosed by the demonstration of elevated very long chain fatty acid (VLCFA) levels in plasma. In contrast, only 80% of female carriers have elevated plasma VLCFA; therefore targeted mutation analysis is the most effective means for carrier detection. Amongst 489 X-ALD families tested at Kennedy Krieger Institute, we identified 20 cases in which the ABCD1 mutation was de novo in the index case, indicating that the mutation arose in the maternal germ line and supporting a new mutation rate of at least 4.1% for this group. In addition, we identified 10 cases in which a de novo mutation arose in the mother or the grandmother of the index case. In two of these cases studies indicated that the mothers were low level gonosomal mosaics. In a third case biochemical, molecular and pedigree analysis indicated the mother was a gonadal mosaic. To the best of our knowledge mosaicism has not been previously reported in X-ALD. In addition, we identified one pedigree in which the maternal grandfather was mosaic for the familial ABCD1 mutation. Less than 1% of our patient population had evidence of gonadal or gonosomal mosaicism, suggesting it is a rare occurrence for this gene and its associated disorders. However, the residual maternal risk for having additional ovum carrying the mutant allele identified in an index case that appears to have a de novo mutation is at least 13%.

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90 Previously reported (Yes/No) Number of pedigrees reporteda CpG (Yes/No) 25 c.124delC ND No 1 N/A 5 c.279_280ins12bp (p.Leu93_Leu94insGluThrGlyLeu) ND No 1 No 6 c.410G>A (p.Trp137X) ND No 1 No 7 c.412_414delCTC (p.Leu139del) ND Yes 2 No 26 c.476del24 ND No 1 N/A 4 c.593C>G (p.Thr198Met) N/A No 1 Yes 8 c.695_696insG (p.Ala233fsX67) ND No 1 Yes 2 c.725G>A (p.Trp242X) Gonosomal No 1 No c.796G>A (p.Gly266Arg) ND Yes 23 Yes 27 c.797G>A (p.Gly266Gln) ND No 1 No 12 c.944C>A (p.Ser315X) ND No 1 Yes 13 c.1201C>T (p.Arg401Trp) ND Yes 12 Yes 14 c.1225-2A>G (splice defect) ND No 1 No 15 c.1390C>T (p.Arg464X) ND Yes 11 Yes 16 c.1553G>A (p.Arg518 Gln) ND Yes 20 Yes 17 c.1567C>T (p.Leu523Phe) ND No 1 No 18 c.1609C>T (p.Gln537X) ND No 1 No 28 c.1619T>G (p.Phe540Cys) ND No 1 No 19 c.1679C>T (p.Pro560Leu) ND Yes 20 Yes 29 c.1679C>T (p.Pro560Leu) ND Yes 20 Yes 20 exon3 to exon10 deletion ND Yesb 9 N/A 30 c.1781-1G>A ND No 1 No 21 c.1816T>C (p.Ser606Pro) ND Yes 3 No 31 c.1850G>A (p.Arg617His) ND Yes 20 Yes 22 c.1876G>A (p.Ala626Thr) ND Yes 10 Yes 23 c.1894A>C (p.Thr632Pro) ND No 2 No 1 c.1899C>A (p.Ser633Arg) Gonosomal Yes 2 Yes 24 c.1918 G>A (p.Glu640Lys) ND No 2 No 3 c.2030G>A (p.Gly677Asp) Gonadal No 1 Yes de novo mutation in male index case with childhood cerebral X-ALD;somatic and/or gonadal mosaicisim; de novo mutationND = none detected; N/A = not applicable; Color codes: in female carrier. Login to comment

[hide] Eight novel ABCD1 gene mutations and three polymor... Hum Mutat. 2001;18(1):52-60. Dvorakova L, Storkanova G, Unterrainer G, Hujova J, Kmoch S, Zeman J, Hrebicek M, Berger J
Eight novel ABCD1 gene mutations and three polymorphisms in patients with X-linked adrenoleukodystrophy: The first polymorphism causing an amino acid exchange.
Hum Mutat. 2001;18(1):52-60., [PMID:11438993]

Abstract [show]
X-ALD is a neurological disorder associated with inherited defects in the ABCD1 (ALD) gene located on Xq28 and with impaired peroxisomal very long-chain fatty acid beta-oxidation. We examined the ABCD1 gene in probands from 11 unrelated X-ALD Czech and Slovak families by the direct sequencing of cDNA or genomic PCR products. In 10 families there were 10 different mutations, eight of which were novel. The spectrum of mutations consists of six point mutations, three microdeletions (1bp, 2bp, 4 bp), and one large deletion (229bp). In the 11th family we detected two novel single-base pair substitutions in exon 1 (c.38 A>C and c.649 A>G), both causing amino acid exchanges (N13T and K217E). Expression studies revealed that only K217E is a deleterious mutation, because a plasmid encoding ALDP with K217E was ineffective in the restoration of defective beta-oxidation in X-ALD fibroblasts. The N13T amino acid exchange, on the other hand, did not affect ALDP function. Thus, N13T represents the first polymorphism causing an amino acid exchange in the ABCD1 gene. As this polymorphism was observed neither in 100 control alleles nor in 300 X-ALD patients who have been sequenced so far world-wide, it seems to be very rare or unique. Two additional novel polymorphisms were found by the sequencing of the ABCD1 gene from our patients: c.-59 C/T in the 5'untranslated region and c.2019 C/T (F673F) in exon 10. The frequencies of these two polymorphisms, were 11/150 and 2/150 control alleles, respectively.

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69 Cell Lines and Cell Culture SV40 transformed ALDP-deficient fibroblasts from a patient (mutation A626T) were kindly provided by Dr. K.D. Smith and Dr. L.T. Braiterman (Baltimore, MD; patient 11 in Watkins et al. [1995]). Login to comment

[hide] Altered expression of ALDP in X-linked adrenoleuko... Am J Hum Genet. 1995 Aug;57(2):292-301. Watkins PA, Gould SJ, Smith MA, Braiterman LT, Wei HM, Kok F, Moser AB, Moser HW, Smith KD
Altered expression of ALDP in X-linked adrenoleukodystrophy.
Am J Hum Genet. 1995 Aug;57(2):292-301., [PMID:7668254]

Abstract [show]
X-linked adrenoleukodystrophy (ALD) is a neurodegenerative disorder with variable phenotypic expression that is characterized by elevated plasma and tissue levels of very long-chain fatty acids. However, the product of the gene defective in ALD (ALDP) is a membrane transporter of the ATP-binding cassette family of proteins and is not related to enzymes known to activate or oxidize fatty acids. We generated an antibody that specifically recognizes the C-terminal 18 amino acids of ALDP and can detect ALDP by indirect immunofluorescence. To better understand the mechanism by which mutations in ALDP lead to disease, we used this antibody to examine the subcellular distribution and relative abundance of ALDP in skin fibroblasts from normal individuals and ALD patients. Punctate immunoreactive material typical of fibroblast peroxisomes was observed in cells from seven normal controls and eight non-ALD patients. Of 35 ALD patients tested, 17 had the childhood-onset cerebral form of the disease, 13 had the milder adult phenotype adrenomyeloneuropathy, 3 had adrenal insufficiency only, and 2 were affected fetuses. More than two-thirds (69%) of all patients studied showed no punctate immunoreactive material. There was no correlation between the immunofluorescence pattern and clinical phenotype. We determined the mutation in the ALD gene in 15 of these patients. Patients with either a deletion or frameshift mutation lacked ALDP immunoreactivity, as expected. Four of 11 patients with missense mutations were also immunonegative, indicating that these mutations affected the stability or localization of ALDP. In the seven immunopositive patients with missense mutations, correlation of the location and nature of the amino acid substitution may provide new insights into the function of this peroxisomal membrane protein. Furthermore, the study of female relatives of immunonegative ALD probands may aid in the assessment of heterozygote status.

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176 In 11 patients, missense mutations that occurred throughout the protein were found: within the transmembrane domains (patients 1, 3, and 4), within the ATP-binding domain (patients 8-12), and on either side of the ATP-binding Table 3 Mutational Analysis of the ALD Gene in IS Unrelated Patients ALDP Patient Phenotype Mutation Consequence Immunoreactivity 1 .................. CALD 825 A-GG K276E + 2.................. AMN 870-2AGAGE291,& 3 .................. CALD 872 G-C E291D 4 .................. AMN 1023 T-IC S342P+ 5 .................. AMN 1166 G-C R389H + 6 .................. CALD 1201 G-AA R401Q + 7 ........ CALD 1415-6 AAG FS@472 8 ........ AMN 1771 G-AA R591Q + 9 ........ Addison 1817 C-T S606L + 10 ................ AMN 1850 G-AA R617H 11 ................ CALD 1876 G-AA A626T 12 ................ Fetus 1884 G-C D629H + 13 ................ CALD 1932 C-UT Q645X 14 ................ AMN 1978 C-OT R660W 15 ........ AMN AExon7-10 Null Mutations in the ALD gene were determined, as described in Methods, in 15 of the ALD patients reported in table 2. Login to comment
178 In 11 patients, missense mutations that occurred throughout the protein were found: within the transmembrane domains (patients 1, 3, and 4), within the ATP-binding domain (patients 8-12), and on either side of the ATP-binding Table 3 Mutational Analysis of the ALD Gene in IS Unrelated Patients ALDP Patient Phenotype Mutation Consequence Immunoreactivity 1 .................. CALD 825 A-GG K276E + 2 .................. AMN 870-2 AGAG E291,& 3 .................. CALD 872 G-C E291D 4 .................. AMN 1023 T-IC S342P + 5 .................. AMN 1166 G-C R389H + 6 .................. CALD 1201 G-AA R401Q + 7 ........ CALD 1415-6 AAG FS@472 8 ........ AMN 1771 G-AA R591Q + 9 ........ Addison 1817 C-T S606L + 10 ................ AMN 1850 G-AA R617H 11 ................ CALD 1876 G-AA A626T 12 ................ Fetus 1884 G-C D629H + 13 ................ CALD 1932 C-UT Q645X 14 ................ AMN 1978 C-OT R660W 15 ........ AMN AExon7-10 Null Mutations in the ALD gene were determined, as described in Methods, in 15 of the ALD patients reported in table 2. Login to comment

[hide] Rat adrenoleukodystrophy-related (ALDR) gene: full... Biochim Biophys Acta. 2001 Jan 26;1517(2):257-69. Albet S, Bentejac M, Savary S, Gondcaille C, Netik A, Berger J, Szpirer C, Troffer-Charlier N, Bugaut M
Rat adrenoleukodystrophy-related (ALDR) gene: full-length cDNA sequence and new insight in expression.
Biochim Biophys Acta. 2001 Jan 26;1517(2):257-69., [PMID:11342107]

Abstract [show]
X-linked adrenoleukodystrophy (X-ALD) is an inherited demyelinating disorder due to mutations in the ALD gene, which encodes a peroxisomal ABC half-transporter (ALDP). It has been suggested that ALDP assembles with ALDRP (adrenoleukodystrophy-related protein), a close homologous half-transporter, to form a functional heterodimer. For the first time full-length ALDRP cDNA (5.5 kb) was cloned, and 5' and 3' RACE analysis revealed that alternative usage of polyadenylation sites generates the two transcripts of 3.0 and 5.5 kb observed in the rat in Northern blot analysis. Southern blotting and chromosomal mapping demonstrated one ALDR locus in the rat genome. Characterisation of the 3' flanking region suggested that an ID sequence might be responsible for high expression of the 5.5 kb ALDRP transcript in rat brain. ALDR gene expression was found to be high in the liver of rats before weaning and very low in adult rats; the reverse developmental regulation was observed in the brain. Fenofibrate, which is a potent inducer of the ALDR gene in the liver of adult rats, could not induce the ALDR gene in suckling rats. The exact significance of this result with regard to development of an efficient pharmacological gene therapy for X-ALD is discussed.

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72 11 with mutation A626T), kindly provided by Dr K.D. Smith and Dr L.T. Braiterman, were transfected by electroporation. Login to comment

[hide] X-linked adrenoleukodystrophy: genes, mutations, a... Neurochem Res. 1999 Apr;24(4):521-35. Smith KD, Kemp S, Braiterman LT, Lu JF, Wei HM, Geraghty M, Stetten G, Bergin JS, Pevsner J, Watkins PA
X-linked adrenoleukodystrophy: genes, mutations, and phenotypes.
Neurochem Res. 1999 Apr;24(4):521-35., [PMID:10227685]

Abstract [show]
X-linked adrenoleukodystrophy (X-ALD) is a complex and perplexing neurodegenerative disorder. The metabolic abnormality, elevated levels of very long-chain fatty acids in tissues and plasma, and the biochemical defect, reduced peroxisomal very long-chain acyl-CoA synthetase (VLCS) activity, are ubiquitous features of the disease. However, clinical manifestations are highly variable with regard to time of onset, site of initial pathology and rate of progression. In addition, the abnormal gene in X-ALD is not the gene for VLCS. Rather, it encodes a peroxisomal membrane protein with homology to the ATP-binding cassette (ABC) transmembrane transporter superfamily of proteins. The X-ALD protein (ALDP) is closely related to three other peroxisomal membrane ABC proteins. In this report we summarize all known X-ALD mutations and establish the lack of an X-ALD genotype/phenotype correlation. We compare the evolutionary relationships among peroxisomal ABC proteins, demonstrate that ALDP forms homodimers with itself and heterodimers with other peroxisomal ABC proteins and present cDNA complementation studies suggesting that the peroxisomal ABC proteins have overlapping functions. We also establish that there are at least two peroxisomal VLCS activities, one that is ALDP dependent and one that is ALDP independent. Finally, we discuss variable expression of the peroxisomal ABC proteins and ALDP independent VLCS in relation to the variable clinical presentations of X-ALD.

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175 Correction of C24:0 B-oxidation by ALDP Exon 10 Deletion Mutant Cell Line Normal A626T A626T A626T ; Construct none pcDNA3 pSK693myc pLB741 C24:0 nmol/hr/mg protein 0.87 0.10 0.17 0.18 Transfection Efficiency NA ND 37% 35% % Correction 53 59 Fibroblasts from an X-ALD patient (A626T) were transfected with the indicated plasmids by electroporation. Login to comment

[hide] Contiguous deletion of the X-linked adrenoleukodys... Am J Hum Genet. 2002 Jun;70(6):1520-31. Epub 2002 Apr 29. Corzo D, Gibson W, Johnson K, Mitchell G, LePage G, Cox GF, Casey R, Zeiss C, Tyson H, Cutting GR, Raymond GV, Smith KD, Watkins PA, Moser AB, Moser HW, Steinberg SJ
Contiguous deletion of the X-linked adrenoleukodystrophy gene (ABCD1) and DXS1357E: a novel neonatal phenotype similar to peroxisomal biogenesis disorders.
Am J Hum Genet. 2002 Jun;70(6):1520-31. Epub 2002 Apr 29., [PMID:11992258]

Abstract [show]
X-linked adrenoleukodystrophy (X-ALD) results from mutations in ABCD1. ABCD1 resides on Xq28 and encodes an integral peroxisomal membrane protein (ALD protein [ALDP]) that is of unknown function and that belongs to the ATP-binding cassette-transporter superfamily. Individuals with ABCD1 mutations accumulate very-long-chain fatty acids (VLCFA) (carbon length >22). Childhood cerebral X-ALD is the most devastating form of the disease. These children have the earliest onset (age 7.2 +/- 1.7 years) among the clinical phenotypes for ABCD1 mutations, but onset does not occur at <3 years of age. Individuals with either peroxisomal biogenesis disorders (PBD) or single-enzyme deficiencies (SED) in the peroxisomal beta-oxidation pathway--disorders such as acyl CoA oxidase deficiency and bifunctional protein deficiency--also accumulate VLCFA, but they present during the neonatal period. Until now, it has been possible to distinguish unequivocally between individuals with these autosomal recessively inherited syndromes and individuals with ABCD1 mutations, on the basis of the clinical presentation and measurement of other biochemical markers. We have identified three newborn boys who had clinical symptoms and initial biochemical results consistent with PBD or SED. In further study, however, we showed that they lacked ALDP, and we identified deletions that extended into the promoter region of ABCD1 and the neighboring gene, DXS1357E. Mutations in DXS1357E and the ABCD1 promoter region have not been described previously. We propose that the term "contiguous ABCD1 DXS1357E deletion syndrome" (CADDS) be used to identify this new contiguous-gene syndrome. The three patients with CADDS who are described here have important implications for genetic counseling, because individuals with CADDS may previously have been misdiagnosed as having an autosomal recessive PBD or SED

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83 Failure of Complementation Studies with X-ALD Fibroblasts to Correct the Defect Somatic-cell hybridization studies were performed with an ALDP immunonegative cell line derived from an individual with X-ALD and the ABCD1 mutation Nt1876GrA (A626T). Login to comment