ABCMdb

ABCD1 p.Val222Leu

Predicted by SNAP2:	A: N (53%), C: N (93%), D: D (80%), E: D (75%), F: D (63%), G: D (71%), H: D (80%), I: N (87%), K: D (85%), L: N (82%), M: N (53%), N: D (71%), P: D (80%), Q: D (66%), R: D (85%), S: D (63%), T: D (53%), W: D (85%), Y: D (80%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, W: D, Y: D,

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[hide] Preferential expression of mutant ABCD1 allele is ... Orphanet J Rare Dis. 2012 Jan 26;7:10. doi: 10.1186/1750-1172-7-10. Salsano E, Tabano S, Sirchia SM, Colapietro P, Castellotti B, Gellera C, Rimoldi M, Pensato V, Mariotti C, Pareyson D, Miozzo M, Uziel G
Preferential expression of mutant ABCD1 allele is common in adrenoleukodystrophy female carriers but unrelated to clinical symptoms.
Orphanet J Rare Dis. 2012 Jan 26;7:10. doi: 10.1186/1750-1172-7-10., [PMID:22280810]

Abstract [show]
BACKGROUND: Approximately 20% of adrenoleukodystrophy (X-ALD) female carriers may develop clinical manifestations, typically consisting of progressive spastic gait, sensory deficits and bladder dysfunctions. A skewing in X Chromosome Inactivation (XCI), leading to the preferential expression of the X chromosome carrying the mutant ABCD1 allele, has been proposed as a mechanism influencing X-linked adrenoleukodystrophy (X-ALD) carrier phenotype, but reported data so far are conflicting. METHODS: To shed light into this topic we assessed the XCI pattern in peripheral blood mononuclear cells (PBMCs) of 30 X-ALD carriers. Since a frequent problem with XCI studies is the underestimation of skewing due to an incomplete sample digestion by restriction enzymes, leading to variable results, we developed a pyrosequencing assay to identify samples completely digested, on which to perform the XCI assay. Pyrosequencing was also used to quantify ABCD1 allele-specific expression. Moreover, very long-chain fatty acid (VLCFA) levels were determined in the same patients. RESULTS: We found severely (>/=90:10) or moderately (>/=75:25) skewed XCI in 23 out of 30 (77%) X-ALD carriers and proved that preferential XCI is mainly associated with the preferential expression of the mutant ABCD1 allele, irrespective of the manifestation of symptoms. The expression of mutant ABCD1 allele also correlates with plasma VLCFA concentrations. CONCLUSIONS: Our results indicate that preferential XCI leads to the favored expression of the mutant ABCD1 allele. This emerges as a general phenomenon in X-ALD carriers not related to the presence of symptoms. Our data support the postulated growth advantage of cells with the preferential expression of the mutant ABCD1 allele, but argue against the use of XCI pattern, ABCD1 allele-specific expression pattern and VLCFA plasma concentration as biomarkers to predict the development of symptoms in X-ALD carriers.

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No. Sentence Comment
53 All samples were tested in Table 1 Clinical Findings, Genotype, X-Chromosome Inactivation (XCI), ABCD1 Allele-Specific Expression (ASE) and Biochemical Findings (VLCFA plasma levels) of X-ALD carriers Nr of family, consultants Age (yrs) Presence of symptoms (age at onset, yrs) Mutations XCI pattern ABCD1 ASE (mut:wt) C26 (nv) C26/C22 (nv) C24/C22 (nv) F1 II-3 67 Yes (45) 410G > A W137X 97:03 84:16 1,09 (<0,75) 48 (<17) 1644 (<1100) F1 III-2 34 No 410G > A W137X 91:09 nd 0,58 (<0,75) 47 (<17) 1482 (<1100) F2 I-2 61 Yes (59) 427C > G P143A 71:29 93:07 0,85 (<0,75) 18 (<17) 1222 (<1100) F2 II-1 38 No 427C > G P143A 85:15 83:17 nd nd nd F2 II-2 35 No 427C > G P143A 76:24 77:23 nd nd nd F3 II-2 73 Yes (45) 428C > A P143H 60:40 38:62 1,45 (<1,50) 28 (<40) 700 (<820) F3 III.1 46 No 428C > A P143H 84:16 84:16 1,53 (<1,50) 40 (<40) 860 (<820) F3 III-2 50 No 428C > A P143H 83:17 75:25 1,75 (<1,50) 37 (<40) 733 (<820) F4 II-3 75 Yes (50) 652C > T; 664G > T P218S; V222L 81:19 82:18 1,57 (<0,75) 19 (<17) 1680 (<1100) F4 III-1 44 No 652C > T; 664G > T P218S; V222L 83:17 81:19 2,38 (<1,50) 53 (<40) 1424 (<820) F4 III-3 45 Yes (29) 652C > T; 664G > T P218S; V222L 89:11 82:18 1,00 (<0,75) 36 (<17) 1611 (<1100) F5 II-1 55 Yes (54) 1202G > A R401Q 98:02 82:18 1,96 (<1,50) 38 (<40) 1031 (<820) F6 II-1 76 Yes (58) 1727T > C L576P 73:27 76:24 2,10 (<0,75) 21 (<17) 1039 (<1100) F7 I-2 72 No 1772G > A R591Q n/a n/a 1,23 (<1,5) 16 (<40) 798 (<820) F7 II-1 44 Yes (34) 1772G > A R591Q 96:04 97:03 2,7 (<1,50) 56 (<40) 957 (<820) F8 II-1 62 Yes (40) 1992G > A W664X 83:17 82:18 3,08 (<1,50) 56 (<40) 1132 (<820) F9 II-1 63 No 293C > T S98L 83:17 93:07 1,82 (<1,50) 37 (<40) 888 (<820) F9 II-3 57 No 293C > T S98L 79:21 75:25 1,99 (<1,50) 42 (<40) 913 (<820) F9 III-2 20 No 293C > T S98L 75:25 61:39 2,65 (<1,50) 46 (<40) 1149 (<820) F10 I-2 63 No 443A > G N148S 86:14 42:58 2,16 (<1,50) 42 (<40) 788 (<820) F10 II-2 40 No 443A > G N148S 96:04 84:16 2,17 (<1,50) 43 (<40) 757 (<820) F11 III-1 67 No 1165C > T R389C 52:48 72:28 0,7 (<1,50) 13 (<40) 572 (<820) F11 III-3 64 No 1165C > T R389C 78:22 34:66 1,1 (<1,50) 16 (<40) 823 (<820) F11 III-5 49 No 1165C > T R389C 98:02 20:80 1,05 (<1,50) 16 (<40) 848 (<820) F11 III-6 46 No 1165C > T R389C 71:29 74:26 1,30 (<1,50) 18 (<40) 1000 (<820) F11 V-1 26 No 1165C > T R389C 57:43 58:42 0,68 (<1,50) 14 (<40) 663 (<820) F12 I-2 53 No 1211C > A S404X 95:05 09:91 nd nd nd F13 I-2 60 No del. ex8-10 n/a 76:24 nd nd nd nd duplicate and one male DNA sample was included in each experiment as a control for enzymatic digestion. Login to comment