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M Anvret

Publications and source records attributed to M Anvret.

At least 109 records · Page 6Linked to original sources
PubMed1992

On laboratory problems in diagnosing mild von Willebrand's disease.

By providing some examples of variations in the levels of von Willebrand factor antigen (vWF:Ag), ristocetin cofactor, and Factor VIII during one month, the authors wish to emphasize the difficulty of diagnosing mild forms of von Willebrand's disease (vWD), especially type I. In three of 15 normal female volunteers the vWF:Ag levels, on some sampling occasions, were so low (0.25-0.30 IU/mL, normal greater than 0.50 IU/mL) that the diagnosis of vWD type I might be made while on other occasions normal levels were obtained. The coefficients of variation (CV) for vWF:Ag in these three women were 12%, 25%, and 43%. However, CVs of similar magnitude were also observed for "non-diseased" males and females. The ratio F VIII/vWF:Ag also varied greatly. In the three women with suspected vWD it was 36%, 15%, and 34%. A representative level for the entire cycle of vWF:Ag and ristocetin cofactor seems to have been obtained in the follicular phase and therefore it is suggested that in order to make the diagnosis of vWD type I, at least in females, blood samples should be taken in this phase.

Adult↗
PubMed1992

Genetic and blood coagulation characterization of "Swedish" families with von Willebrand's disease types I and III: new aspects of heredity.

Twenty-five patients with von Willebrand's disease (vWD) type III were analysed with regard to blood coagulation variables and possible deletions. Nine of the probands and their families were further investigated with DNA linkage analyses. Different patterns of heredity can be suggested in our families with vWD type III, on the basis of blood coagulation analyses. The findings suggest homozygosity in five families and the possibility of compound heterozygosity or a new mutation in the proband in three families. The linkage analyses confirm the results of the coagulation analyses. The segregation of the von Willebrand factor (vWF) gene can be followed in the families, and carrier diagnosis can be made in several of the probands' relatives. The possibility of large deletions in the vWF gene of the probands and their parents was investigated with probes representing the whole vWF cDNA. No deletions were found.

Blood Coagulation↗
PubMed1992

Nonsense mutations of the von Willebrand factor gene in patients with von Willebrand disease type III and type I.

von Willebrand disease (vWD) is the most common inherited bleeding disorder in humans. The disease is caused by qualitative and quantitative abnormalities of the von Willebrand factor (vWF). Genomic DNA from 25 patients with vWD type III, the most severe form of the disease, was studied using PCR followed by restriction-enzyme analysis and direct sequencing of the products. Nonsense mutations (CGA----TGA) were detected in exons 28, 32, and 45 by screening of all the 11 CGA arginine codons of the vWF gene. Two patients were found to be homozygous and five heterozygous for the mutation. Both parents and some of the relatives of the homozygous patients carry the mutation. These are the first reported examples of homozygous point mutations associated with the severe form of vWD. In the three heterozygous probands, one of the parents carried the mutation and had vWD type I. Family studies including parents and family members with or without vWD type I indicated that these three heterozygous patients are likely to be compound heterozygous. Twenty-one individuals from these seven families with vWD type I were found to be heterozygous for the mutation.

Adolescent↗
PubMed1992

Genetics of the Rett syndrome.

The current knowledge concerning the inheritance of the Rett syndrome is reviewed. So far the main interest has been focused on the short arm of the X chromosome as the possible location for the gene for the Rett syndrome. There is, however, no conclusive evidence for such a location. The authors suggests that other possible gene locations also should be investigated.

Cytogenetics↗
PubMed1992

Examination of X chromosome markers in Rett syndrome: exclusion mapping with a novel variation on multilocus linkage analysis.

Rett syndrome is a neurologic disorder characterized by early normal development followed by regression, acquired deceleration of head growth, autism, ataxia, and stereotypic hand movements. The exclusive occurrence of the syndrome in females and the occurrence of a few familial cases with inheritance through maternal lines suggest that this disorder is most likely secondary to a mutation on the X chromosome. To address this hypothesis and to identify candidate regions for the Rett syndrome gene locus, genotypic analysis was performed in two families with maternally related affected half-sisters by using 63 DNA markers from the X chromosome. Maternal and paternal X chromosomes from the affected sisters were separated in somatic cell hybrids and were examined for concordance/discordance of maternal alleles at the tested loci. Thirty-six markers were informative in at least one of the two families, and 25 markers were informative in both families. Twenty loci were excluded as candidates for the Rett syndrome gene, on the basis of discordance for maternal alleles in the half-sisters. Nineteen of the loci studied were chosen for multipoint linkage analysis because they have been previously genetically mapped using a large number of meioses from reference families. Using the exclusion criterion of a lod score less than -2, we were able to exclude the region between the Duchenne muscular dystrophy locus and the DXS456 locus. This region extends from Xp21.2 to Xq21-q23. The use of the multipoint linkage analysis approach outlined in this study should allow the exclusion of additional regions of the X chromosome as new markers are analyzed. This in turn will result in a defined region of the X chromosome that should be searched for candidate sequences for the Rett syndrome gene in both familial and sporadic cases.

Alleles↗
PubMed1991

Identification of the most common mutation within the porphobilinogen deaminase gene in Swedish patients with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is a metabolic disorder characterized by a partial deficiency of the porphobilinogen deaminase (PBGD, EC 4.3.1.8) activity. Previous haplotype analysis combined with genealogical data suggested a common origin of the PBGD gene mutation in the AIP families originating from northern Sweden (Lappland), where the highest prevalence of the disease (1 in 1500) is observed. An AIP family from Lappland consisting of two patients and two unaffected subjects was investigated. The genomic DNA fragments of the PBGD gene were amplified by polymerase chain reaction (PCR) and directly sequenced, and the sequence of the coding region was compared with the normal sequence to identify the mutation. A base substitution, G to A, in exon 10 of the PBGD gene was identified. The mutation changes the codon for Trp198 to a stop codon (nonsense mutation) and creates a recognition site for the restriction enzyme Nhe I. Screening of 33 Swedish AIP families showed that 15 had this mutation. Genealogical data revealed that 12 of the 15 families were related to the northern family. This finding supports the hypothesis of a "founder effect" of the mutation in the families originating from Lappland. In addition, a method is described for detection of specific sequences in the genome by one-sided PCR using Taq polymerase. This method is simple, fast, and economical and can be substituted for hybridization analysis using allele-specific oligonucleotides.

Base Sequence↗
PubMed1991

[Diagnosis of cystic fibrosis with DNA techniques].

The extensive body of genetic and physical mapping data accumulated since the identification of the cystic fibrosis (CF) gene locus on chromosome 7 has made possible the molecular cloning of the gene. A deletion of three DNA base pairs, removing a phenylalanine residue from position 508 of the protein product, accounts for 40-85 per cent of CF mutations in most Western countries, the estimated figure for Sweden being 60 per cent. In the article are discussed findings for three additional mutations (G551D, R553X and G542X), only one allele out of 200 analysed having been found to manifest the R553X mutation alone. Also discussed are DNA techniques for detecting the common mutation, recent progress toward in vivo correction of the defect, and indications and possibilities for future screening programs.

Adult↗
PubMed1991

Aicardi syndrome: early neuroradiological manifestations and results of DNA studies in one patient.

A patient with Aicardi syndrome is presented. We report results of DNA analysis from the patient and her parents with probes mapped to Xp21.3-22.3 in an attempt to localize a deletion in this region. No signs of a microdeletion could be detected, using 5 different DNA markers. Further, it is suggested that a specific combination of cerebral abnormalities may be characteristic of the syndrome and that antenatal ultrasonographic diagnosis may be feasible.

Agenesis of Corpus Callosum↗
PubMed1991

Molecular analysis of 4p deletion associated with Wolf-Hirschhorn syndrome moving the "critical segment" towards the telomere.

We report molecular studies in 2 patients with Wolf-Hirschhorn syndrome, probing genomic DNA from the patients and their parents with markers that have been mapped to 4p16.3. One of the patients was heterozygous for alleles detected by probe F5.53, which maps to the centromeric end of the D4S10 locus, but hemizygous for loci located more distally. The region in common, which was deleted in both these patients, is within 4p16.3. This observation suggests that the gene(s) for Wolf syndrome may be contained within this region, and that the "critical segment" is located more distally than previous cytogenetic observations have suggested. Furthermore, we found that the deletion was of maternal origin in one patient, and of paternal origin in the other.

Abnormalities, Multiple↗
PubMed1991

Genetic heterogeneity of the porphobilinogen deaminase gene in Swedish families with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is an autosomal dominant metabolic disorder affecting the enzyme porphobilinogen (PBG) deaminase in the heme biosynthetic pathway. The highest prevalence of the disorder has been observed in Scandinavia, especially in northern Sweden (Lappland) where it occurs with a prevalence of 1 in 1500. Biochemical assays of the activity and concentration of PBG deaminase in red blood cells, haplotyping with 4 intragenic restriction fragment length polymorphisms (RFLPs) (MspI, PstI, BstNI, ApaLI) using the polymerase chain reaction (PCR) and screening for known base substitutions by oligonucleotide probes was performed in 28 Swedish AIP families. There was no close relationship between haplotype, biochemical findings (PBG deaminase activity, enzyme-linked immunosorbent assay [ELISA], and excess urinary excretion of delta-aminolevulinic acid or PBG), and a specific mutation. Three different haplotypes were identified. The haplotype 2/1/1/2 (MspI/PstI/BstNI/ApaLI; +/-/-/+) was found to be the most frequent among gene carriers (P less than 0.001). The disease segregated with the haplotype 2/1/1/2 in the 10 families originating from northern Sweden. All 28 families were screened for three known point mutations. Only one was found to carry one of these mutations. Thus, the genetic background of AIP is heterogeneous in Sweden.

Alleles↗
PubMed1991

Rett syndrome: exclusion mapping following the hypothesis of germinal mosaicism for new X-linked mutations.

The hypothesis of germinal mosaicism in the unaffected mother of two half-sisters affected with Rett syndrome is postulated to explain the unusual recurrence of this genetic disorder affecting only females (1/10,000); it might be caused by new X-linked mutations with lethality in male fetuses. The analysis of 34 X-linked restriction fragment length polymorphisms (RFLPs) in these two affected females and in their unaffected mother and half-brother, together with the reconstruction of phase for 15 informative RFLPs in somatic cell hybrids retaining a single X chromosome from each female, has made it possible to exclude some regions of the X chromosome as possible sites of the mutation(s) causing Rett syndrome.

Cell Line↗
PubMed1991

Evaluation of DNA-based diagnosis for haemophilia A.

Haemophilia A is an X-linked disorder affecting 1.7/10,000 males. Carrier detection in females and prenatal diagnosis of male foetuses is greatly improved by DNA-based diagnosis. This study describes the use of the polymerase chain reaction (PCR) and allele-specific oligonucleotides (ASO) in a clinical study comprising 190 individuals in 27 families. Prenatal diagnosis was performed in eight cases. Of three male fetuses, two were found to be affected and one unaffected. It is shown that 62% of women in the Swedish population are heterozygous for the intragenic BclI or XbaI polymorphisms and consequently a majority of them (53%) can be analysed in the PCR-based format. Using three intragenic polymorphisms, a combined heterozygosity of 64% was recorded in the females. If the extragenic loci DXS52 and DXS15 were used in addition, 97% of the women could be counselled by DNA-analysis. Our study demonstrates the usefulness of PCR-based analysis of the BclI- and the XbaI-polymorphisms in genetic counselling. The counselling of women with conflicting results between coagulation data and DNA-based linkage analysis is discussed.

Alleles↗
PubMed1991

B cell phenotype-dependent expression of the Epstein-Barr virus nuclear antigens EBNA-2 to EBNA-6: studies with somatic cell hybrids.

The expression of the transformation-associated Epstein-Barr virus (EBV)-encoded nuclear antigens (EBNAs) 1 to 6 and membrane protein LMP-1 was studied in a series of somatic cell hybrids derived from the fusion of the EBV-transformed lymphoblastoid cell line (LCL) KR-4, and the EBV-carrying Burkitt's lymphoma lines Daudi, P3HR-1 and Raji, with non-B cell lines of fibroblast, erythroid, myeloid and epithelial origin. Expression of EBNAs 2 to 6 was down-regulated in the hybrids in parallel with extinction of the B cell markers CD19, CD20, CD21, CD23, HLA class II, and surface or cytoplasmic immunoglobulin. LMP-1 was expressed independently of EBNA-2 in hybrids derived by the fusion of the LMP-1-positive KR-4 and P3HR-1 cell lines with epithelial and myeloid cells, respectively. LMP-1 was down-regulated in hybrids derived by the fusion of P3HR-1 with an erythroid cell line and in the hybrid between Raji and a mouse fibrosarcoma line. EBNA-1 was the only EBV antigen that was regularly expressed in the hybrids regardless of the dominating cellular phenotype. The autonomous expression of EBNA-1 suggests that its regulatory pathway is independent of phenotype-associated cellular or viral factors. In contrast, the expression of EBNAs 2 to 6 appears to require a B cell environment. EBNA-2 was shown to contribute to the regulation of LMP expression in B cells. We show that in LCL-carcinoma hybrids the dominating epithelial phenotype is permissive for LMP expression in the absence of EBNA-2.

Antigens, Viral↗