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Results for “Splicing mutations”

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At least 613 records · Page 34Linked to original sources
PubMed2001

[An acceptor-splice-site mutation responsible for complete androgen insensitivity syndrome].

OBJECTIVE: To study the molecular mechanism of androgen insensitivity syndrome (AIS) and the relationship among androgen receptor's molecular structure, function and clinical manifestation. METHODS: PCR-SSCP analysis was carried out to screen exons from B to H of androgen receptor(AR) gene in a cAIS patient for AR gene mutation; direct DNA sequencing of PCR product was performed to find out the location and the pattern of the mutation. RESULTS: A newly found point mutation G(3346) to T, which is located at intron 5-exon F acceptor splice site in the AR gene, was identified. CONCLUSION: Highly conserved GU-AG structure at splice site plays a crucial role in maintaining normal function of AR.

Adult↗
PubMed2003

A novel splice site mutation in the TRIM37 gene causes mulibrey nanism in a Turkish family with phenotypic heterogeneity.

Mulibrey nanism (muscle-liver-brain-eye nanism; MUL) is an autosomal recessively transmitted disease characterized by severe growth delays of prenatal onset caused by mutations in the TRIM37 gene. Recent studies on the subcellular localization revealed that the TRIM37 (KIAA0898) protein is located in peroxisomes. Therefore, MUL has been classified as a new peroxisomal disorder. Up to now, four mutations have been reported, all of which lead to frameshifts and truncated proteins. In this study, mutation screening was performed for the coding region of the TRIM37 gene in a Turkish family by means of RT-PCR and direct cDNA sequencing. We have identified a novel mutation resulting in a frameshift cosegregating within the family. Finally, we report on the presence of novel splice variants observed in lymphoblastoid cells and muscle tissue of normal subjects and patients.

Base Sequence↗
PubMed1991

Molecular heterogeneity at the phenylalanine hydroxylase locus in the population of the south-west of England.

The phenylalanine hydroxylase gene locus has been studied in 35 independent phenylketonuric families in the south-west of England using RFLP haplotype patterns and allele specific oligonucleotide probes. Haplotype 3 was the most common pattern on mutant chromosomes and there was strict linkage disequilibrium between this haplotype and the splice mutation in exon 12. The R408W mutation in exon 12 occurred on both haplotypes 1 and 2. The R126Q mutation in exon 7 was found only on a rare haplotype 28 pattern. No gene carried the R158Q mutation. More than 60% of mutant genes did not carry these four mutations which were originally described in other European populations. We suggest that the splice mutation arose as a single event and spread throughout northern Europe by population migration and admixture. In addition, we believe the haplotype/mutation associations seen in our population are a reflection of the mixed ancestry of the inhabitants of the British Isles.

Alleles↗
PubMed1999

Molecular studies of Japanese patients with group A xeroderma pigmentosum using polymerase chain reaction and restriction fragment length polymorphism and nonradioactive single strand conformation polymorphism analyses.

Xeroderma pigmentosum is an autosomal recessive disease characterized by extreme sensitivity of the skin to ultraviolet light, which results in a high incidence of early skin cancer. We report here the molecular analysis of the xeroderma pigmentosum group A complementing genes of five Japanese patients with group A xeroderma pigmentosum and their families, by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis, and by PCR and non-radioactive single strand conformation polymorphism (SSCP) analysis using the Pharmacia PhastSystem. Four of the five patients were found to be homozygous for a known splicing mutation of intron 3. One patient was found to be heterozygous for the splicing mutation of intron 3 and a known nonsense mutation of exon 6. This nonradioactive PCR-SSCP technique was as useful for the molecular diagnosis of patients with group A xeroderma pigmentosum as was PCR-RFLP analysis.

Adolescent↗
PubMed1992

De novo splice site mutation in the antithrombin III (AT3) gene causing recurrent venous thrombosis: demonstration of exon skipping by ectopic transcript analysis.

A single basepair substitution at conserved position -1 in the exon 3a donor splice site of the liver-expressed antithrombin III (AT3) gene was detected by PCR/direct sequencing in a patient with sporadic type 1 ATIII deficiency and recurrent venous thrombosis. The lesion, a heterozygous silent AAG----AAA transition at Lys 176 occurred de novo in the proposita. Ectopic transcript analysis of lymphocyte mRNA demonstrated the presence of an abnormally sized mRNA specific to the patient which was shown by cDNA sequencing to lack exon 3a. Oligonucleotide discriminant hybridization demonstrated the absence of any detectable transcript of normal length derived from the disease allele. These findings demonstrate the utility of ectopic transcript analysis in the characterization of defects of mRNA splicing.

Antithrombin III↗
PubMed1996

Expression of human foamy virus reverse transcriptase involves a spliced pol mRNA.

In human foamy virus (HFV) the reverse transcriptase is expressed independently of the Gag protein as a 127-kDa Pol precursor molecule. Evaluating the mechanism of Pol expression we identified a spliced mRNA which uses the main 5' splice donor and a splice acceptor site located in the gag gene. The significance of this spliced transcript for HFV Pol expression was studied by constructing a virus with a mutated splice acceptor site. This virus was unable to express detectable Pol proteins after transient transfection. Replication of the mutant was studied by a sensitive assay based on HFV transactivator-stimulated expression of an integrated lacZ gene under control of the HFV long terminal repeat. Whereas in the first 2 weeks after transfection the mutant replicated 3 to 5 order of magnitude less well than wild-type virus, extracellular titers obtained thereafter were similar to those of wild-type virus. This increase in replication competence was accompanied by a reversion of the mutated splice acceptor site. The results underlined the importance of the spliced pol transcript for HFV replication and pointed to a second mechanism of Pol expression. Indicator gene assays suggest that this other mechanism is likely to be a transactivator-dependent cryptic promoter in the gag gene which gives rise to Pol-encoding transcripts.

Animals↗
PubMed1995

High prevalence of nonsense, frame shift, and splice-site mutations in 16 patients with full-blown Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is a fully penetrant X-linked recessive disorder characterized by immunodeficiency, thrombocytopenia, and severe eczema. WAS is a life-threatening disease, with a poor quality of life and high mortality rate in childhood. The gene responsible for the disease has been localized to the proximal short arm of the X-chromosome and recently isolated through positional cloning and named WAS protein (WASP). We have characterized 17 WAS families. We have developed a rapid, nonradioactive screening protocol for identifying WASP gene alterations in genomic DNA. Our method allows simultaneous evaluation of single strand confirmation polymorphism and heteroduplex formation. We have identified 15 novel mutations that involve single basepair changes, or small insertions or deletions, all of which result in premature stop cordon, frame shift with secondary premature stop codon, or splice site defect. These studies document the considerable heterogeneity of the location of mutations in the WASP gene causing full-blown WAS and show the efficiency and rapidity of a screening approach for mutation identification in WAS that will be useful for carrier detection and prenatal diagnosis.

Base Sequence↗
PubMed1998

Familial Kallmann syndrome: a novel splice acceptor mutation in the KAL gene.

Kallmann syndrome is an inherited disease which is characterised by anosmia (inability to smell) and hypogonadotropic hypogonadism both of which are thought to occur as a result of a failure of correct neuronal migration. To date the only genetic lesions identified are mutations in the X-linked gene, KAL. We conducted a mutation screen of the KAL gene in a family with Kallmann syndrome. This identified a new mutation in the KAL gene which removed an acceptor site at the junction of exon 6/intron 5. Exon 6 of the KAL gene encodes the C-terminal portion of a fibronectin type III domain may be involved in axonal pathfinding. We presume that the described mutation would result in the removal of exon 6 resulting in a frame shift which terminates the protein prematurely. It has been proposed that both mental illness and vesico-ureteric reflux are associated with mutations in the KAL gene. However, results from the family presented here do not show an association between either trait and the KAL gene mutation.

Child↗
PubMed1993

Frameshift and splice-junction mutations in the sterol 27-hydroxylase gene cause cerebrotendinous xanthomatosis in Jews or Moroccan origin.

The sterol 27-hydroxylase (EC 1.14.13.15) catalyzes steps in the oxidation of sterol intermediates that form bile acids. Mutations in this gene give rise to the autosomal recessive disease cerebrotendinous xanthomatosis (CTX). CTX is characterized by tendon xanthomas, cataracts, a multitude of neurological manifestations, and premature atherosclerosis. A relatively high prevalence of the disease has been noted in Jews originating from Morocco. The major objectives of the present investigation were to determine the gene structure and characterize the common mutant alleles that cause CTX in Moroccan Jews. The gene contains nine exons and eight introns and encompasses at least 18.6 kb of DNA. The putative promoter region is rich in guanidine and cytosine residues and contains potential binding sites for the transcription factor Sp1 and the liver transcription factor, LF-B1. Blotting analysis revealed that the mutant alleles do not produce any detectable sterol 27-hydroxylase mRNA. No major gene rearrangements were found and single-strand conformational polymorphism followed by sequence analysis identified two underlying mutations: deletion of thymidine in exon 4 and a guanosine to adenosine substitution at the 3' splice acceptor site of intron 4 of the gene. The molecular characterization of CTX in Jews of Moroccan origin provides a definitive diagnosis of this treatable disease.

Adult↗
PubMed1998

A novel donor splice site mutation in the C1 inhibitor gene of a patient with type I hereditary angioneurotic edema.

We studied the molecular genetic basis of a C1 inhibitor deficiency in a patient with type I hereditary angioneurotic edema using both the polymerase chain reaction and nucleotide sequencing. A single nucleotide change (T-->A) at the GT 5' donor splice recognition motif in the seventh intron of the C1 inhibitor gene was detected. A restriction site analysis of the C1 inhibitor gene in the patient's family indicated that this mutation is correlated with a decreased level of C1 inhibitor activity. A northern blot analysis demonstrated C1 inhibitor mRNA to have a normal size, but its contents were reduced by about 50% compared with a normal subject. As the donor splice site is essential for an excising of the intron during mRNA processing, aberrant mRNA splicing may cause a rapid degradation of the transcript, thus resulting in the onset of hereditary angioneurotic edema.

Adult↗
PubMed1994

Complete androgen insensitivity due to a splice-site mutation in the androgen receptor gene and genetic screening with single-stranded conformation polymorphism.

OBJECTIVE: To characterize the genetic defect in a family with complete androgen insensitivity syndrome and to determine whether single-stranded conformation polymorphism (SSCP) can be used to detect subtle mutations in the androgen receptor (AR) gene. DESIGN: Amplification, subcloning where appropriate, and sequencing of the AR gene in members of the affected family and to use SSCP to differentiate rapidly mutant from normal alleles. SETTING: Reproductive endocrinology clinic and laboratory in a university hospital. PATIENTS: A family of which two sisters (46XY) have complete androgen insensitivity syndrome. RESULTS: A novel single base (G --> A) mutation in the exon G-intron 7 junction of the AR gene caused an abnormal donor splice site leading to complete androgen insensitivity in both affected siblings. Their mother was demonstrated to be the heterozygous carrier of this mutation while the other two males in the family carried the normal allele. Single-stranded conformation polymorphism proved useful for defining the normal, mutant, and heterozygous carrier status of each member of this family. CONCLUSIONS: This new mutation of the human AR gene illustrates the importance of exon G in receptor function. Single-stranded conformation polymorphism is a simple and rapid screening technique that can be used to detect unknown subtle mutations in the AR gene.

Adolescent↗
PubMed1992

Gaucher disease: A G+1----A+1 IVS2 splice donor site mutation causing exon 2 skipping in the acid beta-glucosidase mRNA.

Gaucher disease is the most frequent lysosomal storage disease and the most prevalent Jewish genetic disease. About 30 identified missense mutations are causal to the defective activity of acid beta-glucosidase in this disease. cDNAs were characterized from a moderately affected 9-year-old Ashkenazi Jewish Gaucher disease type 1 patient whose 80-year-old, enzyme-deficient, 1226G (Asn370----Ser [N370S]) homozygous grandfather was nearly asymptomatic. Sequence analyses revealed four populations of cDNAs with either the 1226G mutation, an exact exon 2 (delta EX2) deletion, a deletion of exon 2 and the first 115 bp of exon 3 (delta EX2-3), or a completely normal sequence. About 50% of the cDNAs were the delta EX2, the delta EX2-3, and the normal cDNAs, in a ratio of 6:3:1. Specific amplification and characterization of exon 2 and 5' and 3' intronic flanking sequences from the structural gene demonstrated clones with either the normal sequence or with a G+1----A+1 transition at the exon 2/intron 2 boundary. This mutation destroyed the splice donor consensus site (U1 binding site) for mRNA processing. This transition also was present at the corresponding exon/intron boundary of the highly homologous pseudogene. This new mutation, termed "IVS2 G+1----A+1," is the first splicing mutation described in Gaucher disease and accounted for about 3.4% of the Gaucher disease alleles in the Ashkenazi Jewish population. The occurrence of this "pseudogene"-type mutation in the structural gene indicates the role of acid beta-glucosidase pseudogene and structural gene rearrangements in the pathogenesis of this disease.

Aged↗
PubMed1990

Mutations affecting RNA splicing in man are detected more frequently in somatic than in germ cells.

The spectrum of DNA sequence alterations in the hypoxanthine-guanine phosphoribosyltransferase (hprt) gene of HPRTase-deficient T-lymphocytes isolated from the blood of healthy male donors was determined and compared with the spectrum found in patients suffering from genetic diseases (Lesch-Nyhan syndrome or gouty arthritis) associated with a mutation in the same gene. Most of the T-cell mutants still produced hprt mRNA which was converted into cDNA and used for DNA sequence analysis after amplification using the polymerase chain reaction (PCR). In 39% of the 31 analyzed T-cell mutants of normal donors 1 or 2 exons were completely or partially deleted from hprt mRNA, probably because of a mutation in a splice acceptor site. Among patients suffering from the Lesch-Nyhan syndrome or gouty arthritis, the class of splice mutations amounts only to 7%. These data suggest that carriers of splice mutations often do not show the characteristics of HPRTase deficiency associated with these genetic diseases, because correctly spliced hprt mRNA is still produced at a low level.

Arthritis, Gouty↗
PubMed1997

The alternative H-ras protein p19 displays properties of a negative regulator of p21Ras.

In previous work, we demonstrated that expression of mammalian H-ras genes is controlled by alternative splicing. Mutational analyses indicated that most H-ras premessenger RNA (pre-mRNA) is not processed into mRNA for the usual p21Ras protein, but is recognized instead for processing through an alternative pathway that would produce mRNA for a hypothetical p19Ras protein, which would be a truncated form of p21 with a different carboxyl-terminus. We have raised the possibility that p19 could be a negative regulator of p21, but only small amounts of mature p19 mRNA could be detected and we had no evidence that the protein could be made. We now show by transient and stable transfection experiments that p19 can be produced from complementary DNA (cDNA) expression vectors in human 293 cells, which express early adenoviral genes. However, p19 cDNA inhibited the formation of drug-selected colonies of Rat-1 cells and surviving colonies produced little p19. Colony formation and p19 expression were increased when the cDNA had mutations in the putative effector domain of p19 or when oncogenes believed to act downstream of p21Ras, such as adenoviral E1A, were included in the transfections. These results indicate that p19 can act as an inhibitor of p21. We also show that authentic p19 can be abundantly expressed in 293 cells from H-ras gene constructs with mutations favoring the alternative splicing pathway, which suggests that regulated splicing could support overproduction of p19 under natural conditions. Our work indicates that mutations abolishing alternative H-ras splicing may not only contribute to oncogenesis by increasing the production of p21, but also by interfering with the production of an antiproliferative H-ras activity.

Alternative Splicing↗