FISHing Tips: What Every Clinician Should Know About 1p19q Analysis in Gliomas Using Fluorescence in situ Hybridisation

1p19q co-deletion is a chromosomal alteration associated with primary brain tumours of oligodendroglial histology. It is an established predictive and prognostic biomarker that informs whether patients are offered radiotherapy, chemotherapy or both. In the near future, 1p19q co-deletion status may also be incorporated into the reclassification of gliomas. Analysis is commonly carried out using fluorescence in situ hybridisation (FISH) because it is a reliable and validated laboratory technique. The result is generally considered to be dichotomous (1p19q co-deletion present or absent), but there are subtleties in interpretation that are of clinical relevance. Separate centres may interpret certain chromosome deletion patterns differently. Pivotal trials in mixed and pure anaplastic oligodendrogliomas have used slightly different FISH probe ratios as the cut-off for chromosome deletion. Here we review the clinical implications of this variability and review the process of 1p19q co-deletion assessment using FISH in gliomas from a clinician's perspective. We also consider common alternative methods of analysis

Reduced response of Cystathionine Beta-Synthase (CBS) to S-Adenosylmethionine (SAM): Identification and functional analysis of CBS gene mutations in Homocystinuria patients

Item does not contain fulltextA reduced response of cystathionine beta-synthase (CBS) to its allosteric activator S-adenosylmethionine (SAM) has been reported to be a cause of CBS dysfunction in homocystinuria patients. In this work we performed a retrospective analysis of fibroblast data from 62 homocystinuria patients and found that 13 of them presented a disturbed SAM activation. Their genotypic background was identified and the corresponding CBS mutant proteins were produced in E. coli. Nine distinct mutations were detected in 22 independent alleles: the novel mutations p.K269del, p.P427L, p.S500L and p.L540Q; and the previously described mutations p.P49L, p.C165Rfs*2, p.I278T, p.R336H and p.D444N. Expression levels and residual enzyme activities, determined in the soluble fraction of E. coli lysates, strongly correlated with the localization of the affected amino acid residue. C-terminal mutations lead to activities in the range of the wild-type CBS and to oligomeric forms migrating faster than tetramers, suggesting an abnormal conformation that might be responsible for the lack of SAM activation. Mutations in the catalytic core were associated with low protein expression levels, decreased enzyme activities and a higher content of high molecular mass forms. Furthermore, the absence of SAM activation found in the patients' fibroblasts was confirmed for all but one of the characterized recombinant proteins (p.P49L). Our study experimentally supports a deficient regulation of CBS by SAM as a frequently found mechanism in CBS deficiency, which should be considered not only as a valuable diagnostic tool but also as a potential target for the development of new therapeutic approaches in classical homocystinuria

UK 2022 Consensus on Normal Tissue Dose-Volume Constraints for Oligometastatic, Primary Lung and Hepatocellular Carcinoma Stereotactic Ablative Radiotherapy

The use of stereotactic ablative radiotherapy (SABR) in the UK has expanded over the past decade, in part as the result of several UK clinical trials and a recent NHS England Commissioning through Evaluation programme. A UK SABR Consortium consensus for normal tissue constraints for SABR was published in 2017, based on the existing literature at the time. The published literature regarding SABR has increased in volume over the past 5 years and multiple UK centres are currently working to develop new SABR services. A review and update of the previous consensus is therefore appropriate and timely. It is hoped that this document will provide a useful resource to facilitate safe and consistent SABR practice