Novel characterization of a breakpoint in F8: an individualized approach to gene analysis when PCR and MLPA results contradict. (27th January 2015)

• Record Type: Journal Article
• Authors: Pezeshkpoor, B.; Theophilus, B. D. M.; Guilliatt, A. M.; Oldenburg, J.; Williams, M. D.; El‐Maarri, O.
• Is Part Of: Haemophilia. Volume 21:Number 3(2015:May)
• Page Start: 392
• Page End: 397
• Publication Date: 2015-01-27
• Subjects: Hemophilia -- Periodicals; 616.1572005
• DOI: 10.1111/hae.12606
• Languages: English
• ISSNs: 1351-8216

Abstract

<abstract abstract-type="main" id="hae12606-abs-0001"> <title>Summary</title> <p>Haemophilia A is an X‐linked bleeding disorder caused by heterogeneous mutations in the <italic>F8</italic> gene. Two inversion hotspots in intron 22 and intron 1, as well as point mutations, small insertions and deletions in the <italic>F8</italic> gene account for causal mutations leading to severe haemophilia A. Rarely, novel molecular mechanisms lead to a haemophilia A phenotype which cannot be completely characterized by routine molecular diagnostic methods. Here, we characterized the molecular abnormality in a boy with a severe haemophilia A phenotype. On investigation by PCR and DNA sequencing, exon 18 of <italic>F8</italic> repeatedly failed to amplify. However, analysis by multiplex ligation‐dependent probe amplification demonstrated the presence of exon 18 sequence, suggesting a more complex rearrangement than a single exon deletion. The analysis of exon 18 and its flanking regions by inverse PCR revealed a complex mutation comprising insertions of extragenic sequences from Xq28 along with a partial duplication of exon 18. Based on the successful analysis and characterization of the familial breakpoint, we developed a PCR‐based diagnostic approach to detect this defect in family members in whom no diagnostic test could be offered until this time.</p> </abstract>