Molecular Pathology

Molecular Pathology is a field of pathology that utilises the principles, techniques and tools of molecular biology, which is a highly essential tool for the practice of precision medicine.

Indications

• Myeloid neoplasms
  • Acute Myeloid Leukaemia.
  • Myeloproliferative neoplasms.
  • Myelodysplastic syndromes.
  • Myelodysplastic/myeloproliferative neoplasms.
  • Myeloid/lymphoid neoplasms with eosinophilia and gene rearrangement.
  • Mastocytosis.
• Lymphoid neoplasms


• B-lymphoblastic leukaemia/lymphoma
• Chronic lymphocytic leukaemia
• Plasma cell neoplasms
• High-grade B-cell lymphoma

Procedures

Using different technologies such as real-time PCR, Fluorescence in situ hybridization (FISH), Fragment analysis, and Next Generation Sequencing (NGS) helps to accurately characterise the genetic abnormality causing the disease.

• PCR allows the amplification of fragments of DNA to facilitate detection.PCR may be used to look for certain changes in a gene or chromosome, which may help find and diagnose a genetic condition or a disease, such as cancer.
• Real-time PCR starts with DNA/RNA template (extracted from the patient sample), and the targets of interest (e.g. JAK2 mutation in myeloproliferative neoplasms or BCR-ABL fusion transcripts in CML) are amplified many million times, which can be detected in real time and reported qualitatively (detected/not detected) or quantitatively(e.g. copies/ml).
• FISH - molecular cytogenetics method/laboratory technique for detecting and locating a specific DNA sequence on a chromosome. The samples are processed to facilitate the binding of target DNA with the probe DNA labelled with fluorochrome, which allows subsequent visualisation by fluorescence microscope.
• Fragment analysis: After target amplification (conventional PCR), separation and visualisation of fluorescently labelled fragments (DNA) based on size (e.g. Microsatellite Instability).
• NGS (Next generation sequencing) - Enables simultaneous detection of diagnostically and prognostically relevant genetic alterations in multiple genes for which targeted therapy is available. The assay starts with library preparation, and the resulting template is clonally amplified and enriched, which are further sequenced. Genetic alterations are annotated using commercially available software, which links it to available relevant therapy, clinical trials and risk stratification details.

Advantages

• Solid tumours:
  • From 10ng of input nucleic acid, it detects actionable targets across 52 genes. If an actionable target is identified, targeted therapy is given, which targets specific genes and proteins that are involved in the growth and survival of cancer cells without affecting the normal cells. It works by blocking the growth signals essential for the proliferation of cancer cells, accelerates its destruction and also decreases the production of new blood vessels required for its survival. This therapy will prolong the survival of the patient and improve the overall outcome of the patient.
  • Helps in the diagnosis of soft tissue sarcomas as well as small round cell tumours by detecting the characteristic cytogenetic abnormality.
• Myeloid neoplasms:
  • Simultaneously detects all the relevant genetic abnormalities across 79 genes in a single assay rather than sequentially. This test is very useful for the diagnosis of myeloid neoplasms and its classification as per the guideline recommendation. It provides prognostic information as to whether the patient will require standard treatment or high dose chemotherapy or bone marrow transplant for permanent cure. It also helps in selecting the patients for targeted therapy.
• Lymphoid neoplasms:
  • Helps in risk stratification and guides treatment.