| 1. |
- Halldén, Christer, et al.
(författare)
-
Investigation of disease-associated factors in haemophilia A patients without detectable mutations
- 2012
-
Ingår i: Haemophilia. - : Wiley-Blackwell Publishing Ltd. - 1351-8216 .- 1365-2516. ; 18:3, s. e132-e137
-
Tidskriftsartikel (refereegranskat)abstract
- To investigate disease causing mechanism in haemophilia A patients without detectable mutation. Screening for F8 mutations in 307 haemophilia A patients using: re-sequencing and inversion PCR, reverse transcription (RT-PCR) of mRNA, MLPA analysis, haplotyping using SNP and microsatellite markers. No F8 mutations were detected in 9 of the 307 patients (2.9%) using re-sequencing and inversion PCR. MLPA analysis detected duplication in exon 6 in one patient and RT-PCR showed no products for different regions of mRNA in four other patients, indicating failed transcription. No obvious associations were observed between the phenotypes of the nine patients, their F8 haplotypes and the putative mutations detected. The mutation-positive patients carrying the same haplotypes as the mutation-negative patients show a multitude of different mutations, emphasizing the lack of associations at the haplotype level. VWF mutation screening and factor V measurements ruled out type 2N VWD and combined factor V and VIII deficiencyrespectively. To further investigate a possible role for FVIII interacting factors the haplotypes/diplotypes of F2, F9, F10 and VWF were compared. The nine patients had no specific haplotype/diplotype combination in common that can explain disease. Duplications and faulty transcription contribute to the mutational spectrum of haemophilia A patients where conventional mutation screening fail to identify mutations.
|
|
| 2. |
|
|
| 3. |
- Kling, S., et al.
(författare)
-
Moderate haemophilia B in a female carrier caused by preferential inactivation of the paternal X chromosome
- 1991
-
Ingår i: European Journal of Haematology. - : Wiley. - 0902-4441 .- 1600-0609. ; 47:4, s. 257-261
-
Tidskriftsartikel (refereegranskat)abstract
- The case of a female with moderate haemophilia B is reported. She is the only affected member of her family, and factor IX RFLP analysis shows her to have inherited no maternal markers for polymorphisms located in the first intron and 8 Kb 3' of the polyadenylation signal (DdeI and HhaI, respectively). This clearly indicates a deletion involving at least the last 7 exons of the factor IX gene. Her other factor IX gene inherited from her healthy father is normal as her son is also healthy. This suggests the patient's haemophilia to be due to gross bias in the proportion of factor IX-producing cells with an inactive paternal X chromosome. Methylation studies on the 5' region of the PGK gene show that virtually all the patient's lymphocytes carry a hypermethylated and presumably an inactive paternal X chromosome. The reason for this bias in the activity of her two X chromosomes is not clear, as no chromosomal alterations were found.
|
|
| 4. |
- Kling, S., et al.
(författare)
-
Origin of mutation in sporadic cases of haemophilia-B
- 1992
-
Ingår i: European Journal of Haematology. - : Wiley. - 0902-4441 .- 1600-0609. ; 48:3, s. 142-145
-
Tidskriftsartikel (refereegranskat)abstract
- Of the 45 haemophilia-B patients registered at the haemophilia centre in Malmo, Sweden, 24 are the sole members of their families to be affected, and in 13 of these 24 cases, ascendant relatives are available for study. Detection of the gene defect showed the mutation to be de novo in the proband in 3 of these 13 cases, and inherited from a carrier mother in the remaining 10 cases. All 10 carrier mothers were shown to have de novo mutations, as the patients' grandfathers were phenotypically and/or haematologically normal, and the grandmothers were non-carriers. Seven restriction fragment length polymorphisms (RFLPs) of the factor IX gene were used to determine whether the de novo mutations of the 10 carrier mothers were of paternal or maternal origin. In 6/10 cases, the RFLP patterns were informative, and indicated the mutation to be of paternal origin.
|
|
| 5. |
|
|
| 6. |
- Knobe, Karin, et al.
(författare)
-
Functional analysis of the EGF-like domain mutations Pro55Ser and Pro55Leu, which cause mild hemophilia B.
- 2003
-
Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 1:4, s. 782-790
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the functional role of two mutations, Pro55Ser and Pro55Leu, located in the N-terminal Epidermal Growth Factor-like domain (EGF1) of coagulation factor (F) IX. Both mutations cause mild hemophilia B with habitual FIX coagulant activities of 10-12% and FIX antigen levels of 50%. We found that activation by FVIIa/TF and FXIa was normal for FIXPro55Ser, but resulted in proteolysis of FIXPro55Leu at Arg318-Ser319 with a concomitant loss of amidolytic activity, suggesting intramolecular communication between EGF1 and the serine protease domain in FIX. This was further supported by experiments using an anti-EGF1 monoclonal antibody. Activation of FX by FIXaPro55Ser was impaired in both the presence and the absence of phospholipid or FVIIIa, indicating that Pro55 is not directly involved in binding to FVIIIa. We also studied the effect of the two Pro55 mutations on Ca2+ affinity and found only small changes. Thus, the Pro55Ser mutation causes hemophilia primarily through to an impaired ability to activate FX whereas at least in vitro the Pro55Leu defect interferes with the activation of FIX.
|
|
| 7. |
- Knobe, Karin, et al.
(författare)
-
Functional Analysis of the Factor IX Epidermal Growth Factor-Like Domain Mutation Ile66Thr Associated with Mild Hemophilia B.
- 2006
-
Ingår i: Pathophysiology of Haemostasis and Thrombosis. - : S. Karger AG. - 1424-8832 .- 1424-8840. ; 35:5, s. 370-375
-
Tidskriftsartikel (refereegranskat)abstract
- he present study focused on the functional role of the mutation Ile66Thr located in the N-terminal epidermal growth factor-like domain of coagulation factor IX (FIX). This mutation causes mild hemophilia B with approximately 25% FIX coagulant activity and FIX antigen levels of around 90% of normal. In the 3-dimensional structure of porcine FIXa and in the subsequent 3-dimensional model of human FIXa that we have previously developed, residue 66 is exposed to the solvent and can be replaced by many amino acids, including Thr, without affecting the major folding/stability of the molecule. This is consistent with the basically normal antigen levels observed. We found that the FIX Ile66Thr mutant was activated to a normal extent by FVIIa/TF and FXIa. However, the ability of FIX Ile66Thr to activate FX was impaired in both the presence and absence of FVIIIa, indicating that Ile66 is not directly involved in the binding of FIX to FVIIIa.
|
|
| 8. |
- Knobe, Karin, et al.
(författare)
-
Why does the mutation G17736A/Val107Val (silent) in the F9 gene cause mild haemophilia B in five Swedish families?
- 2008
-
Ingår i: Haemophilia. - : Wiley. - 1351-8216 .- 1365-2516. ; May 4, s. 723-728
-
Tidskriftsartikel (refereegranskat)abstract
- The mutation G17736A/Val107Val (silent) was found in five of a total of 86 families with haemophilia B in Sweden. It is unlikely that five families with analogous clinical expression will have the same polymorphism, which is not found in other patients or normal subjects, or that they will be the only families in the population without any other causative mutation. All affected individuals in the five families were found to have factor IX (F9) coagulation activity 15-20 U dL(-1), corresponding F9 protein levels and the same clinical history of mild haemophilia. Lymphocyte mRNA was extracted from one of the haemophiliacs and from a healthy male. RT-PCR of the mRNA and subsequent PCR amplification produced cDNA fragments of the same length from the patient and the normal subject, indicating no exon skipping or retention of introns. Sequencing of cDNA from codon 68 in exon D to codon 180 in exon F revealed that the patient had the G17736A mutation but no other abnormalities. We conclude that G17736A/Val107Val causes mild haemophilia B. Although, exon skipping and retention of introns can be excluded as pathophysiological mechanisms, it is plausible that the studied mutation has more subtle effects on a splicing site or interferes with a splicing enhancer site. Also, changes to synonymous codons may reduce the translation rate and thereby alter F9 protein folding in vivo, which would explain the phenotype. Confirmation of these assumptions requires methods that are more sensitive than those available today, and our discussion illustrates the existing obstacles.
|
|
| 9. |
- Ljung, R., et al.
(författare)
-
Antenatal diagnosis of haemophilia B by amplification and electrophoresis of an exon fragment with a short deletion
- 1992
-
Ingår i: European Journal of Haematology. - 0902-4441. ; 49:4, s. 215-218
-
Tidskriftsartikel (refereegranskat)abstract
- Cartier identification and antenatal diagnosis were performed in 2 sisters by electrophoretic separation of the normal and abnormal bands obtained after amplification of a fragment of exon h in the factor IX gene. The mutation in the family had been characterised as an 8-base pair (bp) deletion in exon h. By amplification of a 326 bp fragment containing the site of deletion, the shorter 318 bp band of the haemophilia B gene could be separated by electrophoresis of the fragments. The comprehensive data collection at the Haemophila Centre is of vital importance in the genetic counselling of haemophilia families, and was a crucial step for the successful diagnoses in these sisters.
|
|
| 10. |
- Ljung, R. C R, et al.
(författare)
-
Origin of mutation in sporadic cases of haemophilia A
- 1999
-
Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048. ; 106:4, s. 870-874
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to define the origin of mutation in sporadic cases of severe haemophilia A. The series was composed of 31 families with sporadic severe haemophilia A in the geographical catchment area of the Malmo haemophilia centre. The mutation was characterized in 29/31 families: inversion type 1 (n = 11), inversion type 2 (n = 3), other inversion (n= 1), small or partial deletion (n = 6), insertion (n = 2), non-sense mutation (n = 4) and mis-sense mutation (n = 2). Of 29 probands, eight carried a de novo mutation, whereas the proband's mother was found to carry the mutation in 21/29 families. Of the 21 carrier mothers, 16 had de novo mutations (i.e. the proband's maternal grandfather and grandmother were non-carriers). Owing to the lack of samples from the grandparents, origin could not be determined in the remaining five families. Polymorphisms of the FVIII gene were used to determine whether the de novo mutation of the carrier mother was of paternal or maternal origin. In 15/16 cases the mutation was of paternal origin and in 1/16 cases of maternal origin. In the series as a whole, mutation frequency was 6-fold higher in males than in females, but no differences in the ratio of sex-specific mutations rates was found among different types of mutation.
|
|
