Molecular diagnostics

Molecular diagnostics

Molecular diagnostics in Pathology uses molecular techniques to determine specific abnormalities in tumour cells. The pathologists and clinical molecular biologists (KMBP) at MUMC+ work closely together in this process. Tissues or cells collected from the patient are first examined histologically or cytologically by the pathologists. The genetic material (DNA or RNA) is then extracted from the tumour cells in the laboratory, after which molecular characteristics are determined using state-of-the-art laboratory techniques. Molecular determinations can also be performed on the basis of cell-free DNA (cfDNA) isolated from the patient's blood, for example when no tissue material from the patient is available, or in the context of disease course monitoring during therapy. The aim of these molecular studies is to achieve optimal diagnosis, prognosis and targeted therapy (personalised medicine).

The Pathology Department of the MUMC+ has considerable expertise in determining the presence or absence of molecular abnormalities in tumour cells. This concerns expertise regarding mutations in the (cf)DNA, in which one or several bases are changed, larger DNA fragments are copied or lost, but also regarding chromosomal changes such as translocations. At the RNA level, pathogenic changes can, for instance, be detected in the form of alternative RNA splicing transcripts, or fusion gene transcripts. There is thereby extensive knowledge on how change in gene(s) affect protein activity and molecular signalling cascades, and thus may determine tumour characteristics, in order to arrive at an optimal diagnosis and treatment plan on this basis. Direct consultation between doctor, pathologist and molecular biologist is of great importance here, and takes place, among other things, in the form of a Molecular Tumour Board (MTB) consultation, for which special, complex cases can be submitted.

 Overview of molecular techniques available:

  • Targeted DNA mutation/CNV analysis based on next generation sequencing (NGS) smMIPs panels, Idylla PCR, ddPCR
  • Broad DNA mutation/CNV analysis based on the TruSight Oncology 500 DNA NGS panel
  • Broad RNA fusion gene analysis based on the TruSight Oncology 500 RNA NGS panel
  • (quantitative real-time) PCR
  • In situ hybridisation
  • Fragment analysis
  • Clonality analysis based on LOH and/or NGS
  • Microsatellite analysis
  • B- and T-cell clonality analysis
  • Pyrosequencing and methylation research
  • Sanger sequencing
  • High resolution melting curve analysis (HRM)

Information for doctors:

  • The presence of the DNA changes is determined using PCR-based analysis methods and associated readout systems. Despite the fact that these determinations can be performed routinely, the determinations are often laborious, also in terms of interpretation of the data. Hence, you should take into account a period until the results are obtained as indicated in the document Molecular Diagnostics Pathology processing times.
  • For each individual determination, clear (quality) criteria have been established that absolutely must be met before we can arrive at a reliable result. Among other things, a test may have to be performed several times per patient before a reliable result can be issued. This may delay the issuance of a result. On the other hand, a test may give an 'unassessable' result if the material is of insufficient quality for analysis. Each result is assessed for quality by a molecular biologist (KMBP) before it is issued.
  • The results are sent to the doctor/applicant with a result form showing the cumulative results of the respective patient and a cover letter. .
  • Emergency determinations should be requested in the context of point 1. If urgency is required in a determination, this should be discussed by telephone with the relevant contacts for the analysis and clearly noted on the request form.
  • For reliable PCR analysis, we need at least 1 cm2 of cut surface area of patient material with sufficient tumour percentage and/or 4 ml of uncoagulated blood (on Streck or EDTA tubes) with sufficient target cell frequency.
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