ISSN:1059-7794    

DOI:10.1002/humu.1380010202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe present an update on mutations and polymorphisms in the human X chromosome located pyruvate dehydrogenase E1α gene. A total of 20 different mutations are tabulated. The mutations include deletions, insertions, and point mutations. Certain sequences seem particularly prone to mutation. Most of the mutations are found in exons 10 and 11. Furthermore, four of the mutations are seen in unrelated patients. Little is known about how the mutations affect the structure or function of the pyruvate dehydrogenase complex. © 1992 Wiley‐Liss,

ISSN:1059-7794    

DOI:10.1002/humu.1380010203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMucopolysaccharidosis type I (MPS‐I) is an autosomal recessive genetic disease caused by a deficiency of the glycosidase α‐L‐iduronidase which is required for the lysosomal degradation of the glycosaminoglycans heparan sulfate and dermatan sulfate. Patients with MPS‐I store these partially degraded glycosaminoglycans in their lysosomes. MPS‐I patients have a wide range of clinical presentations, that makes it difficult to predict patient phenotype which is needed for genetic counselling and also impedes the selection and evaluation of patients undergoing therapy such as bone marrow transplantation. We report the presence of a common mutation accounting for 31% of MPS‐I alleles in a study of 64 MPS‐I patients. The mutation was originally detected by chemical cleavage and then direct PCR sequencing. The mutation is a single base substitution that introduces a stop codon at position 402 (W402X) of the α‐L‐iduronidase protein and is associated with an extremely severe clinical phenotype in homozygotes. Patients who are compound heterozygotes having one allele carrying the W402X mutation have a wide range of clinical phenotypes. Based on polymorphisms within the α‐L‐iduronidase gene, W402X is associated with three different haplotypes, implying that there is more than one origin for the mutation or that intragenic recombination has occurred. W402X introduces a MaeI restriction endonuclease site into MPS‐I alleles enabling its simple detection, which should make possible the assessment of the efficacy of bone marrow transplantation in MPS‐I patients homozygous for W

ISSN:1059-7794    

DOI:10.1002/humu.1380010204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA representative multicenter cysic fibrosis (CF) mutation analysis on about half of all known cystic fibrosis patients of the 5 East German Länder is reported. Analyses for 17 mutations, among them DeltaF508, R553X, G542X, S549R, N, I, G551D, S1255X, R347P, H, and Y122X, were performed. As expected, the ΔF508 mutation in exon 10 of the CFTR gene is the major gene alteration causing CF in our patients. However, in comparison to studies from Western Germany, a significantly lower percentage of just over 60% is found in our patients, resembling data obtained from slavonic populations. The severe phenotype of cystic fibrosis is most frequently associated with homozygosity for the ΔF508 mutation. No particular allele association could be found with the intermediate and mild phenotypes of this disease. The next most frequent of the investigated mutations in R553X (13.3% of non‐ΔF chromosome) followed by R347P (9.2%) and G542X (4.4%). © 1992 Wiley‐L

ISSN:1059-7794    

DOI:10.1002/humu.1380010205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractDeficiency of cystathionine β‐synthase (CBS) causes the most common form of inherited homocystinuria. We developed a simple CBS expression system inE. colito screen for pathogenic mutations in affected individuals. Portions of patient cDNAs were amplified by PCR and used to replace the corresponding segments of normal human CBS cDNA in the bacterial expression plasmid pHCS3. Hybrid CBS was expressed inE. coliand the segments of patient's cDNA which extinguished CBS activity were sequenced to identify the mutation. The first study of a pyridoxine‐responsive patient using this screen revealed that of the clones which contained either the middle or the 3′‐portion of his cDNA, about half were devoid of catalytic activity. Subsequent sequencing of the affected segments confirmed a compound heterozygosity for a maternal T833→C transition (I278T) and for a paternal A→C transversion in the intron 11 splice acceptor. The latter mutation leads to an in‐frame deletion of exon 12 (nt 1224‐1358, amino acids W408 to G453). This bacterial expression system proved to be a rapid screening method for localizing pathogenic mutations in CBS, allowing us to sequence the affected portions of mutant cDNA within 7–10 days of harvesting cultured fibroblasts. © 1

ISSN:1059-7794    

DOI:10.1002/humu.1380010206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis study describes a patient with a thalassemia intermedia‐like phenotype in whom β‐globin gene sequencing detected a novel abnormal hemoglobin (Hb) due to a T‐C substitution at codon 114 of the β‐globin gene arising as a de novo mutation. The abnormal variant was designated Hb Brescia after the place of birth of the propositus. Normal sequences were detected at the in trans β‐globin locus. In addition, α‐globin gene analysis detected a triple α‐globin locus which was inherited from the father. The T‐C change at position 114 of the β‐globin gene results in a leucine to proline substitution (Leu‐Pro) in the G‐helix. The resulting Hb tetramer is highly unstable and precipitates forming inclusion bodies in the peripheral red blood cells. Moreover, the Leu‐Pro substitution interferes negatively with the four α1β1contact points of the G‐helix most likely adversely affecting the αβ dimer formation. The very severe phenotype presented by our patient is unusual in a heterozygote for an unstable Hb variant and may be explained by the coinheriance of the triple α

ISSN:1059-7794    

DOI:10.1002/humu.1380010207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe genetic defects responsible for most phenylketonuria (PKU) and hyperphenylalaninemia (HPA) cases are located in the phenylalanine hydroxylase (PAH) gene. Approximately 50–60 mutations have been reported in Caucasians and are reflected in a wide range of clinical severities. Most mutations are linked to specific haplotypes, as defined by eight polymorphic restriction sites in the PAH gene. We hypothesized that there is at least one mild mutation linked to haplotype 12 in the Swedish PKU/HPA population, since 7 of 8 patients carrying haplotype 12 had mild HPA. Sequence analysis revealed a C‐to‐G transversion at the second base of codon 322, resulting in a substitution of glycine for alanine, in four mutant haplotype 12 genes, and a G‐to‐A transition at the second base of codon 408, resulting in a substitution of glutamine for arginine, in another three mutant haplotype 12 genes. These mutations segregated with mutant haplotype 12 alleles in nuclear families but were not present on normal or other mutant alleles. Both mutations were tested in a eukaryotic expression system in which enzyme activities of different mutant PAH enzymes reflect the relative severities of the mutations, although these in vitro activities cannot be translated directly into in vivo hepatic activities. The A322G mutant PAH had about 75% and the R408Q mutant PAH about 55% of the wild‐type PAH enzyme activity. These in vitro activities are the highest reported for mutant PAH enzymes produced in the same expression system. The A322G and R408Q mutations should therefore be the mildest PAH mutations yet identified and expressed, a conclusion supported by the finding of these mutations in only very mildly affected patients. © 1992 Wil

ISSN:1059-7794    

DOI:10.1002/humu.1380010208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractComplete sequence analysis of 194 human phenylalanine hydroxylase genes from PKU patients originating from West Germany and Bulgaria revealed 13 different mutations within exon 7 of the gene. Four of these mutations (T238P: ACT → CCT; L242F: CTC → TTC; R252G: CGG → GGG; and 1043Δ11: nt 1043–nt 1053 deleted) have so far not been described in the literature. Including these new mutations at least 21 different gene lesions and one sequence polymorphism exist for exon 7. Despite this large number unbiased calculation of the mutation frequency/exon size ratio does not provide conclusive evidence that exon 7 is a hot spot for disease causing mutations. Extensive screening during our experiments also failed to demonstrate the existence of excessive polymorphism in this part of the gene. It might therefore be speculated that the functional importance of the highly conserved exon 7 sequence accounts for the clustering of observed mutations which result in clinically manifest PKU. In addition we report our experience in regard to the resolution capacity of denaturing gradient gel electrophoresis (DGGE), a nonradioactive technique for the rapid screening of unknown mutations in exon 7. © 1992 Wiley

ISSN:1059-7794    

DOI:10.1002/humu.1380010209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractMutations at the phenylalanine hydroxylase (PAH) locus are the major cause of hyperphenylalaninemia. We have previously described four mutations (M1V, IVS12nt1, R408W, and S349P) at the PAH locus in French Canadians with ancestry in eastern Quebec. Here we report (1) identification of another mutation, on a haplotype 9 chromosome, which converts codon 65 from isoleucine (ATT) to threonine (ACT), (2) expression analysis of the I65T mutation in COS cells demonstrating 75% loss of both immunoreactive protein and enzyme activity, and (3) expression analysis of the most prevalent PKU allele (M1V) in eastern Quebec, showing nondetectable levels of PAH protein and activity, a finding compatible with a mutation in the traslation initiation codon. Homozygosity for M1V and codominant inheritance of I65T/R408W were both associated with classical phenylketonuria. © 1992 Wiley‐Liss, I

ISSN:1059-7794    

DOI:10.1002/humu.1380010210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractIllegitimately transcribed phenylalanine hydroxylase mRNA was amplified using the polymerase chain reaction from both fibroblasts and Epstein‐Barr virus‐transformed lymphocytes. This method was used to study mutations of this gene in patients with phenylketonuria and known point mutations were easily detected. Illegitimate transcription was successful studying splicing defects and it was found that the previously described mutation which changes G to A at the 5′ donor site of intron 7 causes exon 7 to be spliced out. © 1992 Wiley‐L

ISSN:1059-7794    

DOI:10.1002/humu.1380010211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY