Genetic analysis of a pedigree affected with X-linked adrenoleukodystrophy / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with X-linked adrenoleukodystrophy presenting as spastic paraplegia of the lower limbs.@*METHODS@#Genomic DNA was extracted from peripheral blood samples of the patient and his mother. Potential variant was detected with a panel for genes associated with spastic paraplegia. Candidate variant was verified by PCR and Sanger sequencing.@*RESULTS@#Both the proband and his mother presented with walking difficulty. A previously known variant, c.623T to A (p.V208E), was identified in the ABCD1 gene mapped on chromosome X in both.@*CONCLUSION@#X-link adrenoleukodystrophy should be taken into account as a possible diagnosis for this pedigree.

A novel missense mutation resulting in X-linked adrenoleukodystrophy in female heterozygotes of a Chinese family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify ABCD1 gene mutation in a Chinese family with three heterozygous female patients.</p><p><b>METHODS</b>Four fragments covering the entire coding sequence of the ABCD1 gene from one of the female patients were amplified by reverse transcription-PCR. The PCR products were directly sequenced. The result of sequencing was confirmed by restriction enzyme digestion of PCR products from genomic DNA. Human ABCD1 gene and ALD protein were aligned with those of rat, monkey, mouse and cattle by Clustal X 1.83. Softwares of Motif Scan, TMpred and ESYpred3D were used to predict the effect of the mutation on the structure of the ALD protein.</p><p><b>RESULTS</b>A novel missense mutation, CAC to CGC, was found at codon 283 of the ABCD1 gene from the patient, resulting in the replacement of histidine by arginine. This mutation abolished an Msl I site in the gene. Her son was free from this mutation. The mutated amino acid residue (283H) was highly conservative in evolution, and the mutation caused a dramatic change in the structure of the ALD protein.</p><p><b>CONCLUSION</b>Three female patients heterozygous for ABCD1 gene mutation were first reported in China, and a novel mutation, p.H283R, was identified in this X-ALD family.</p>

Prenatal diagnosis of X-linked adrenoleukodystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To make prenatal dignosis of X-linked adrenoleukodystrophy (ALD) for the prevention of the disease.</p><p><b>METHODS</b>Eighteen amniocenteses were performed on 17 suspected carriers of X-ALD during 18-30 gestation weeks. The very long chain fatty acids (VLCFAs) levels of cultured amniocytes were tested by gas chromatography-mass spectrometry (GC/MS). The plasma VLCFAs levels were measured in 8 of the 18 prenatal diagnosed children when they were born or after abortion. ABCD1 gene mutation analysis was carried out in 8 cases by PCR and sequencing. ALDP of amniocytes was tested by Western blotting in 2 cases from a family, one female, another male, and the VLCFAs of cultured amniocytes were increased in both of them.</p><p><b>RESULTS</b>Among the 18 fetuses, 10 were males and 8 were females. The VLCFAs levels of the cultured amniocytes were increased in 3 males and 4 females. The postnatal plasma VLCFAs were normal in 5 cases with normal VLCFAs levels of amniocytes, and increased in 3 cases with high VLCFAs levels of amniocytes. ABCD1 gene mutations were found in 4 cases with high VLCFAs levels of amniocytes, no mutation was found in other 4 cases with normal VLCFAs levels of amniocytes. ALDP of amniocytes could be detected in the female with high VLCFAs levels of amniocytes, and it could not be detected in the male with high VLCFAs levels of amniocytes. Three male fetuses with high VLCFAs levels of amniocytes were aborted. The others who were born were normal clinically so far.</p><p><b>CONCLUSION</b>The prenatal diagnosis is very important for the prevention of ALD. Amniocyte VLCFAs level analysis combined with ABCD1 gene mutation analysis and ALDP test could make a proper prenatal diagnosis.</p>

Avoiding the interference of ABCD1 pseudogenes in the molecular diagnosis of X-linked adrenoleukodystrophy by double amplification refractory mutation system / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To avoid the interference of ABCD1 pseudogenes, the amplification refractory mutation system (ARMS) was used to analyze the mutation of ABCD1 gene in the molecular diagnosis of X-linked adrenoleukodystrophy (ALD).</p><p><b>METHODS</b>The upstream primers (wild primer and mutation primer) were designed according to the principle of primer-design in ARMS. In addition, a common downstream primer was designed in the same way to discriminate ABCD1 gene from its prologous pseudogenes. The genomic DNA isolated from the peripheral blood leukocytes of the family members and normal controls was amplified by PCR.</p><p><b>RESULTS</b>In double ARMS, a specific product of 107bp could be amplified from genomic DNA of the patient with R617C mutation in ABCD1 gene and his mother, while the same product was not found when the genomic DNA of the patient's father and normal controls was used. Thus, the interference of ABCD1 pseudogenes in molecular diagnosis of ALD was excluded successfully at genomic DNA level.</p><p><b>CONCLUSION</b>Double ARMS is a quick and effective method to eliminate the interference of the pseudogenes in detecting ABCD1 gene mutations.</p>

Screening for carrier and prenatal diagnosis of X-linked adrenoleukodystrophy / 中华儿科杂志

<p><b>OBJECTIVE</b>X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder characterized by progressive demyelination of the central nervous system, adrenal cortex insufficiency and accumulation of saturated very long chain fatty acids (VLCFAs) in tissues and body fluids due to the impaired beta-oxidation in peroxisomes. X-ALD shows a wide range of phenotypic variation. Childhood cerebral form (CCER) is the most common phenotype with severe neurological symptoms and often the average interval from onset to total disability or death is 3 years. So far no effective treatment is available for the underlying defect. Screening for carriers of mutated relevant gene and prenatal diagnosis are very important for the prevention of the disease. In this study, the authors explored the method of carrier screening and prenatal diagnosis of X-ALD.</p><p><b>METHODS</b>The plasma VLCFAs levels of 83 suspected carriers for ALD were determined by using GC/MS and ABCD1 gene mutational analysis was performed in 31 of them. Amniocentesis was performed in 9 suspected carriers for ALD during 18 - 30 gestational weeks. The VLCFAs level of cultured amniocytes was tested with GC/MS. ABCD1 gene mutational analysis was performed on two cases (one was a male and the other a female) whose VLCFAs levels of amniocytes were found elevated. The plasma VLCFAs levels were measured in five of the nine prenatally diagnosed children when they were 1 day to 3.5 years old.</p><p><b>RESULTS</b>Fifty-one of 83 suspected carriers had high plasma VLCFAs levels; 29 of 31 suspected carriers showed ABCD1 gene mutation. Among the nine fetuses, four were males and five were females. The VLCFAs levels of the cultured amniocytes were high in two cases, one was female and the other a male. ABCD1 gene mutational analysis of these two cases showed a 871G > A (E291K) mutation and a 726G > A (W242X) mutation, respectively, which confirmed the biochemical result. The VLCFAs levels were normal in the rest of cases and five of them were confirmed by postnatal plasma VLCFAs assay.</p><p><b>CONCLUSION</b>The carrier screening and prenatal diagnosis are very important for prevention of the X-ALD. Only the combined use of plasma VLCFAs level analysis and ABCD1 gene mutational analysis could detect X-ALD carriers correctly. ABCD1 gene mutational analysis and postnatal plasma VLCFAs level test verified that amniocytes VLCFAs level analysis is a reliable prenatal diagnostic method for this disease.</p>

Prenatal molecular diagnosis of adrenoleukodystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To carry out prenatal diagnosis on two fetuses of different pedigrees with X-linked adrenoleukodystrophy (ALD).</p><p><b>METHODS</b>The amniotic fluid was obtained with the help of a clinical doctor and the genomic DNA was isolated from it. Maternal DNA contamination was excluded by fluorescent STR profiling, The R617G mutation found in the first pedigree was searched in genomic DNA of amniotic fluid cells (AFC) from fetus 1 by amplification refractory mutation system (ARMS) and dot DNA hybridization while the P534R mutation found in pedigree 2 was analyzed in the AFC genomic DNA of fetus 2 by restrictive digestion with Hae II and DNA direct sequencing.</p><p><b>RESULTS</b>A specific band (185 bp) was detected from the genomic DNA of the first fetus and his mother by using mutation primer in ARMS but not from that of the first fetus's father and unrelated controls. DNA dots were visualized only in the fetus 1 and carrier when using the mutation probe in DNA hybridization. In the other ALD family, the PCR product (506 bp) of the second fetus which spanned the site of P534R mutation could not be digested with Hae II and no mutation was detected in the ABCD1 gene from the genomic DNA of the fetus 2 by using DNA direct sequencing.</p><p><b>CONCLUSION</b>Fetus 1 had R617G mutation on his ABCD1 gene and he was an adrenoleukodystrophy hemizygote. Fetus 2 had no P534R mutation on his ABCD1 gene and he was a normal hemizygote.</p>

X-linked adrenoleukodystrophy ABCD1 gene mutation analysis in China / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate mutations of ABCD1 gene in X- linked adrenoleukodystrophy (ALD) patients in China.</p><p><b>METHODS</b>Polymerase chain reaction and DNA direct sequencing were employed to analyze the 10 exons of ABCD1 gene in 25 ALD patients.</p><p><b>RESULTS</b>Seventeen mutations in different exons (except exons 4, 9 and 10) were identified in 18 of 25 patients. Most of the mutations were missense mutations, including R182P, G266R, H283D, S404P, N509I, R518G, L520Q, Q556R, S606L and R617C, four (H283D, S40 4P, N509I, R518G) of 10 missense mutations were novel. Also identified were 3 nonsense mutations (W132X, W242X, W595X), 1 dinucleotides deletion mutation (1414 del AG) resulting in frameshift, and 1 base pair deletion at splice acceptor site (IVS5-6 del C). Two synonymous mutations (L516L and V349V) appeared simultaneously in 2 unrelated patients, and no other mutations could be found with them in all 10 exons screened.</p><p><b>CONCLUSION</b>There were no hot spot mutations in ABCD1 gene in China. Mutations in gene were found over 70% of patients with ALD in China. The ABCD1 gene mutations identified revealed no obvious correlation between the type of mutation and phenotype.</p>

Mutational analysis of three Chinese pedigrees with adrenoleukodystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the mutational genotype of three Chinese families with X-linked adrenoleukodystrophy (X-ALD: MIM#300100).</p><p><b>METHODS</b>Total RNA was extracted from the peripheral blood leukocytes of patients 1, 2 and the mother of patient 3, using RNA blood Mini kit (QIAGEN). After reverse transcription, cDNA was amplified in four overlapping segments. The PCR products were purified and directly sequenced. To confirm the mutations, the genomic DNA was isolated from the patients and their family members using DNA blood isolation kit (MO-BIO) and analyzed by PCR-restrictive digestion or amplification refractory mutation system.</p><p><b>RESULTS</b>Three distinct mutations were detected in the ABCD1 gene of the three pedigrees. A mutation of CCC-->CGC was detected at codon 534 of the ABCD1 gene from patient 1, resulting in the arginine for proline substitution. A change of GGG-->AGG was found at codon 266 of the second patient's gene, accompanied with the replacement of glycine by arginine. A mutation of CGC-->GGC was found at codon 617 in one ABCD1 allele of the third patient's mother, leading to the glycine for arginine substitution. The three mutations were confirmed through restriction analysis or amplification refractory mutation system.</p><p><b>CONCLUSION</b>Three ABCD1 gene missense mutations were detected in three unrelated Chinese families with X-linked adrenoleukodystrophy, one of which, the mutation (P534R), is novel in Chinese with ALD, and the other two G266R and R617G mutations, have been reported outside China.</p>

Analysis on mutation of adrenoleukodystrophy gene in exon 1 and exon 5 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To elucidate the molecular mechanism of X-linked adrenoleukodystrophy(ALD) in Chinese.</p><p><b>METHODS</b>Polymerase chain reaction in exon 1, exon 5 and their flanking sequences and direct DNA sequencing of ALD gene were performed in four patients, their mothers and twenty normal individuals as controls.</p><p><b>RESULTS</b>A splice mutation was identified in the interface of exon 5 and intron 5 (1875 G-->A). This splice mutation in 5' end of intron 5 might lead to abnormal splice in exon 5 and exon 6 and bring about unstable and abnormal ALD protein; the lignoceryl CoA ligase could not transport very long chain fatty acids (VLCFA) into peroxisome and could not function normally; consequently, defective beta-oxidation of VLCFA in peroxisome could result in an accumulation of VLCFAS in the central nervous system, adrenal gland and blood.</p><p><b>CONCLUSION</b>The splice mutation in 5' end of intron 5 leading to abnormal splice in exon 5 and exon 6 appears to be one of the causes of X-linked recessive adrenoleukodystrophy.</p>

Preliminary analysis of mutations in X-linked adrenoleukodystrophy gene(ABCD1) in Chinese patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the mutations in exon 6 of ABCD1 gene encoding adrenoleukodystrophy protein(ALDP) in Chinese X-linked adrenoleukodystrophy (ALD MIM 300100) patients.</p><p><b>METHODS</b>Genomic DNA from 14 unrelated patients and two patients' parents with X-linked ALD was extracted using standard procedures from the peripheral blood leukocytes. Polymerase chain reaction (PCR) and DNA direct sequencing were employed to analyze exon 6 of ABCD1 gene.</p><p><b>RESULTS</b>Three mutations in exon 6 were identified in 3 of 14 patients. One mutation was deleted 1 base pair at splice acceptor-site (1489-6 del C). It was not clear what the effect of this mutation is on the ALD protein, maybe induce splicing error. One missense mutation: T1559A(L520Q). These two patients' mothers were heterozygous. The third patient had a mutation: G1548A (L516 L), which is a known polymorphism. It was not a disease causing mutation, so there should be another mutation in this patient.</p><p><b>CONCLUSION</b>For the first time, mutations in ABCD1 are identified in Chinese ALD patients in the mainland of China. No major gene deletion or rearrangement is detected in exon 6. Despite many mutations having been identified in patients with these clinical phenotypes, the genotype-phenotype correlations have not been clarified, suggesting that other genetic or environmental factors may also be involved in determining phenotypic expression in ALD. Two carriers are also confirmed.</p>