Characterization of duplication breakpoints in the factor VIII gene

Zimmermann, Marcel; Oldenburg, Johannes; Müller, C. R.; Rost, S.

doi:10.1111/j.1538-7836.2010.04040.x

Cited by 33 publications

(52 citation statements)

References 34 publications

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“…73–74 In females, dosage analysis using MLPA can also be used to identify heterozygous partial or complete gene deletions or duplications. 75–76 F8 mutations may be detected in >50% of cases referred for “possible 2N VWD or hemophilia A”. 72 When F8 mutations are absent, VWF can be analysed.…”

Section: Differential Diagnosismentioning

confidence: 99%

von Willebrand disease

James

Goodeve

2011

Genetics in Medicine

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von Willebrand disease (VWD) is a common inherited bleeding disorder characterized by excessive mucocutaneous bleeding. Characteristic bleeding symptoms include epistaxis, easy bruising, oral cavity bleeding, menorrhagia, bleeding after dental extraction, surgery and/or childbirth and in severe cases, bleeding into joints and soft tissues. There are three subtypes: types 1 and 3 represent quantitative variants and type 2 is a group of four qualitative variants: 1) type 2A - characterized by defective von Willebrand factor (VWF) -dependent platelet adhesion because of decreased high molecular weight (HMW) VWF multimers, 2) type 2B - caused by pathologically increased VWF-platelet interactions, 3) type 2M - caused by decreased VWF-platelet interactions not based on the loss of HMW multimers and 4) type 2N - characterized by abnormal binding of VWF to FVIII. The diagnosis of VWD requires specialized assays of von Willebrand factor (VWF) and/or molecular genetic testing of VWF. Severe bleeding episodes can be prevented or controlled with intravenous infusions of virally-inactivated plasma-derived clotting factor concentrates containing both VWF and FVIII. Depending on the VWD type, mild bleeding episodes usually respond to intravenous or subcutaneous treatment with desmopressin, a vasopressin analog. Other treatments that can reduce symptoms include fibrinolytic inhibitors and hormones for menorrhagia.

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Section: Differential Diagnosismentioning

confidence: 99%

von Willebrand disease

James

Goodeve

2011

Genetics in Medicine

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“…In our index case, the characterization of duplication breakpoints is still in progress, with no sequencing information available. In the attempt to elucidate the possible mechanisms behind this rearrangement, we performed a bioinformatic analysis, as repetitive elements, such as short interspersed nuclear elements (SINEs), are known to be frequently involved in duplication mechanisms [10]. Both introns 1 and 6 harbor a SINE/AluY repeat with 87% homology at nucleotides 154 241 443–154 241 175 and 154 210 740–154 210 476, respectively (RefSeq NC_000023, on negative strand), according to RepeatMasker analysis.…”

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confidence: 99%

Aberrant F8 gene intron 1 inversion with concomitant duplication and deletion in a severe hemophilia A patient from Southern Italy

Sanna

Ceglia

Tarsitano

et al. 2013

Journal of Thrombosis and Haemostasis

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Intron 1 and intron 22 inversions (inv1 and inv22) represent the most prevalent mutations in the F8 gene (F8) (1-5% and 40-45%, respectively) causative of severe haemophilia A (HA) [1]. These alterations result from intrachromosomal recombination between intronic regions (int1h-1 and int22h-1, respectively) and their homologous extragenic copies in the telomeric position (int1h-2 and int22h-2/3, respectively) [1]. Inv1 causes an altered F8 structure with the translocation and inversion of the 5¢ region including exon 1 in the extragenic site, giving rise to two chimeric mRNAs: one containing the promoter and first exon of the F8 followed by some exons of the VBP1 gene; the other one formed by the promoter and coding sequences of the C6.1A gene joined to a part of the intron 1 and exons 2-26 of the F8 [2]. The clinical effect of this rearrangement is a severe phenotype with the absence of functional factor (F)VIII. According to literature data, the prevalence of inv1 ranges from 0% to 5% in severe HA patients from different countries [3,4]. In our cohort of 135 unrelated severe HA patients from Southern Italy, inv1 was found in four patients (2.9%) [5]. Here, we report the case of a severe HA patient, who showed an unusual pattern for inv1 associated with a complex gene rearrangement not described to date.The propositus is a Caucasian young male diagnosed with severe HA at the age of 1 year because of a positive family history. The causative F8 mutation in his affected uncle or the carrier status in his mother had not been previously searched for. The patient was treated with recombinant FVIII concentrates with no personal or family history of inhibitor development. We first analyzed the patient for both F8 inversions. This analysis excluded inv22 but showed a novel abnormal pattern for inv1, compared with those previously reported in literature, with two bands: one corresponding to the normal int1h-1 region (1908 bp) and the other corresponding to the band with the inversion of the int1h-1 sequence (1323 bp), as a heterozygous female, suggesting the presence of more than two copies of the int1h region (Fig. 1A). No bands of the int1h-2 region were detected, indicating a deletion within the homologous extragenic copy or a new rearrangement of sequences flanking the int1h-2 repeat not detectable by the PCR method used (Fig. 1A). We also investigated the presence of inv1 in his relatives: both mother and sister were carriers of the same aberrant pattern plus the 1191-bp fragment specific for the normal homologous extragenic int1h-2 sequence. The affected uncle was not available for molecular analysis. To confirm the direct diagnosis, linkage analysis was performed in this family, using intragenic (intron 18 BclI and intron 19 HindIII RFLP) and extragenic (DXS52 VNTR) polymorphisms, matching up with the same genetic profile. Furthermore, in the patient sequencing analysis of the F8, including all 26 exons, flanking intron/exon boundaries, promoter, 5¢ and 3¢ regions, did not reveal other mutations. In this family, a...

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“…7,8 Large duplications are associated with different severity of HA depending on the localization, length of exons involved, and on whether the duplications generate an in-frame or out-frame protein. 9,10 In a large HA cohort from Belgium undergoing diagnostic analysis, 11 two male patients with moderate and severe phenotypes were found with an abnormal band pattern of intron 22 inversion on Southern blotting (SB) and large duplications involving F8 gene exons 1-22 using MLPA. These cases were further analyzed using highresolution custom array comparative genomic hybridization (CGH).…”

Section: Introductionmentioning

confidence: 99%

Intron 22 homologous regions are implicated in exons 1–22 duplications of the F8 gene

et al. 2013

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The intron 22 inversion found in up to 50% of severe hemophilia A patients results from a recombination between three intron 22 homologous copies (int22h). This study evaluated the implication of these copies in the formation of extended duplications comprising exons 1-22 of the factor 8 (F8) gene and their association with hemophilia and mental retardation. Two hemophilic patients with moderate and severe phenotypes and a third nonhemophilic patient with developmental delay were studied. All exhibited a duplication of F8 gene exons 1-22 identified by multiplex ligation-dependent probe amplification along with abnormal patterns on Southern blotting and unexpected long-range PCR amplification. Breakpoint analysis using array comparative genomic hybridization was performed to delimit the extent of these rearrangements. These duplications were bounded on one side by the F8 intragenic int22h-1 repeat and on the other side by extragenic int22h-2 or int22h-3 copies. However, the simultaneous identification of a second duplication containing F8 gene exons 2-14 for the moderate patient and the classical intron 22 inversion for the severe patient are considered in this study as the genetic causal defects of hemophilia. This study shows that the well-known int22h copies are involved in extended duplications comprising F8 gene exons 1-22. These specific duplications are probably not responsible for hemophilia and intellectual disability, but should be carefully considered in genetic counseling, while continuing to investigate the causal mutation of hemophilia.

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Characterization of duplication breakpoints in the factor VIII gene

Cited by 33 publications

References 34 publications

von Willebrand disease

von Willebrand disease

Aberrant F8 gene intron 1 inversion with concomitant duplication and deletion in a severe hemophilia A patient from Southern Italy

Intron 22 homologous regions are implicated in exons 1–22 duplications of the F8 gene

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