RT Journal Article SR Electronic T1 Custom pyrosequencing assay to detect short BRAF deletions in Langerhans cell histiocytic lesions JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 533 OP 536 DO 10.1136/jclinpath-2020-206974 VO 74 IS 8 A1 Fanélie Jouenne A1 Aurélie Sadoux A1 Gwenaël Lorillon A1 Baptiste Louveau A1 Emmanuelle Bugnet A1 Veronique Meignin A1 Samia Mourah A1 Abdellatif Tazi YR 2021 UL http://jcp.bmj.com/content/74/8/533.abstract AB Langerhans cell histiocytosis (LCH) is a rare inflammatory myeloid neoplastic disease driven by activating mutations in the mitogen-activating protein kinase signalling pathway, including the BRAF V600E mutation and BRAF deletions (BRAFdel). Next-generation sequencing and whole exome sequencing (WES) are valuable and powerful approaches for BRAFdel identification, but these techniques are costly and time consuming. Pyrosequencing is an alternative method that has the potential to rapidly and reliably identify gene deletions. We developed a custom pyrosequencing assay to detect the exon-12 BRAFdel in 18 biopsies from adult patients with LCH, which were all genotyped in parallel using Sanger sequencing and WES. A BRAFdel was detected in 7/18 (39%), 6/18 (33%) and 3/18 (17%) LCH lesions using WES, pyrosequencing and Sanger, respectively, with good concordance between the WES and pyrosequencing results (Kappa-coefficient=0.88). Therefore, our pyrosequencing assay is reliable and useful for detecting BRAFdel, particularly in BRAF V600E-negative LCH lesions, for which targeted treatment is indicated.