1P19Q /DEL Oligodendroglioma by fish (AKU) at Dr. Essa Lab

Understanding the 1P19Q /DEL Oligodendroglioma by FISH (AKU) Test

The diagnostic landscape of neuro-oncology has evolved dramatically over the last decade. In the past, brain tumors were classified solely based on their histopathological appearance under a light microscope. Today, the World Health Organization (WHO) classification of Central Nervous System (CNS) tumors mandates molecular characterization for an accurate diagnosis. Among these molecular markers, the co-deletion of chromosome arms 1p and 19q (1p/19q co-deletion) stands out as a critical diagnostic, prognostic, and predictive biomarker. The 1P19Q /DEL Oligodendroglioma by fish (AKU) at Dr. Essa Lab is a highly specialized molecular test designed to detect this genetic alteration in brain tumor tissues.

This test utilizes Fluorescence In Situ Hybridization (FISH) technology, a powerful cytogenetic technique that allows pathologists to visualize specific DNA sequences on chromosomes. By using fluorescently labeled DNA probes that target the 1p36 and 19q13 regions, molecular pathologists can determine whether these chromosomal arms are deleted. The presence of a concurrent deletion of both the short arm of chromosome 1 (1p) and the long arm of chromosome 19 (19q), known as 1p/19q co-deletion, is the defining genetic hallmark of oligodendroglioma.

The clinical importance of identifying this co-deletion cannot be overstated. It serves as a definitive diagnostic tool to distinguish oligodendrogliomas from other morphologically similar gliomas, such as diffuse astrocytomas and glioblastomas. Furthermore, the 1p/19q co-deletion is a powerful prognostic indicator, associated with significantly longer overall survival and progression-free survival. It is also a predictive biomarker, indicating a highly favorable response to specific therapeutic regimens, including alkylating chemotherapy (such as procarbazine, lomustine, and vincristine [PCV] or temozolomide) and radiation therapy. Dr. Essa Lab, a trusted name in diagnostic excellence in Karachi, Pakistan, offers this advanced molecular assay to ensure patients receive the most accurate diagnosis and personalized treatment planning.

Clinical Procedure: What to Expect

Patient Preparation

Because the 1P19Q /DEL Oligodendroglioma by fish (AKU) at Dr. Essa Lab is performed on tissue samples previously obtained during a surgical procedure, there is no direct physical preparation required from the patient at the time of the laboratory test. Patients do not need to fast, restrict medications, or undergo any physical preparation for this molecular assay. Instead, the preparation involves the submission of appropriate diagnostic materials. The patient or their healthcare provider must arrange for the transfer of the Formalin-Fixed Paraffin-Embedded (FFPE) tissue block (often referred to as the biopsy block) and the corresponding histopathology slides to Dr. Essa Lab. It is crucial that the tissue block contains an adequate amount of viable tumor cells (typically at least 30% to 50% tumor content) to ensure the accuracy of the FISH analysis. Patients should also provide all relevant clinical history, previous histopathology reports, and imaging results to assist the molecular pathology team in their evaluation.

During the Procedure

The laboratory procedure for the 1P19Q /DEL Oligodendroglioma by fish (AKU) at Dr. Essa Lab is a multi-step molecular process conducted by highly trained laboratory technologists and pathologists. Once the FFPE tissue block is received, thin sections (usually 4 to 5 micrometers thick) are cut and mounted on specialized glass slides. The tissue sections undergo deparaffinization and pretreatment to make the target DNA accessible to the molecular probes. Next, locus-specific fluorescent probes for the 1p36 and 19q13 regions, along with reference probes for the centromeres of chromosomes 1 and 19, are applied to the slides. The DNA is denatured and allowed to hybridize overnight. Following hybridization, post-hybridization washes are performed to remove unbound probes, and the cell nuclei are stained with a fluorescent counterstain (DAPI). The slides are then analyzed under a high-resolution fluorescence microscope. The molecular pathologist counts the fluorescent signals in a minimum of 100 non-overlapping tumor nuclei to calculate the ratio of target-to-reference signals, determining whether a deletion is present.

When is a 1P19Q /DEL Oligodendroglioma by fish (AKU) Performed?

Differentiating Oligodendroglioma from Other Gliomas

Physicians request this test when a patient presents with a brain tumor that shows glial features under the microscope, but a definitive diagnosis cannot be made by histology alone. Distinguishing oligodendroglioma from astrocytoma is critical because their clinical courses, treatment protocols, and prognoses differ significantly. The presence of the 1p/19q co-deletion confirms a diagnosis of oligodendroglioma, whereas its absence, especially in the presence of TP53 or ATRX mutations, points toward an astrocytoma.

Guiding Chemotherapeutic and Radiotherapeutic Decisions

Oncologists routinely order this molecular test to determine the most effective treatment strategy for patients diagnosed with diffuse gliomas. Patients with 1p/19q co-deleted oligodendrogliomas show an exceptionally high sensitivity to chemotherapy regimens, particularly the PCV combination and temozolomide, as well as radiotherapy. Identifying this genetic profile allows oncologists to confidently prescribe aggressive chemoradiotherapy, which has been shown to double the median survival time in these patients compared to those without the co-deletion.

Establishing Long-Term Prognosis and Survival Expectations

This test is performed to provide patients and their families with accurate prognostic information. Oligodendrogliomas harboring the 1p/19q co-deletion are characterized by an indolent clinical course and a significantly more favorable prognosis. Knowing the co-deletion status helps neuro-oncologists estimate progression-free survival and overall survival, allowing for realistic long-term planning and customized follow-up imaging schedules.

Resolving Diagnostic Ambiguity in Mixed Gliomas

Historically, many brain tumors were classified as oligoastrocytomas or mixed gliomas due to overlapping histological features. The 1P19Q /DEL Oligodendroglioma by fish (AKU) test is performed to resolve these ambiguous cases. Under modern WHO guidelines, mixed gliomas are genetically resolved into either oligodendrogliomas (if 1p/19q co-deleted and IDH-mutated) or astrocytomas (if 1p/19q intact), eliminating diagnostic uncertainty and standardizing patient care.

Evaluating Recurrent or Progressive Brain Tumors

In cases where a patient experiences a recurrence or progression of a previously diagnosed brain tumor, this test may be performed on the newly resected tissue. It helps determine if the molecular profile of the tumor has remained stable or if clonal evolution has occurred. Confirming the persistent presence of the 1p/19q co-deletion helps guide second-line therapeutic choices and clinical trial eligibility.

What Does a 1P19Q /DEL Oligodendroglioma by fish (AKU) Detect?

The 1P19Q /DEL Oligodendroglioma by fish (AKU) test is highly sensitive and specific, capable of detecting a wide range of chromosomal copy number variations and structural alterations. Specifically, the assay detects and evaluates the following clinical findings:

• Presence of concurrent 1p and 19q co-deletion, confirming a classic oligodendroglioma profile.
• Absence of 1p/19q co-deletion, suggesting an alternative diagnosis such as astrocytoma or glioblastoma.
• Isolated deletion of the short arm of chromosome 1 (1p36 locus) with an intact 19q arm.
• Isolated deletion of the long arm of chromosome 19 (19q13 locus) with an intact 1p arm.
• Intact diploid status for both 1p and 19q loci, indicating no chromosomal loss in these regions.
• Polysomy of chromosome 1, characterized by more than two signals for both the target and reference probes.
• Polysomy of chromosome 19, showing an increased copy number of both target and reference signals.
• Monosomy of chromosome 1, representing a loss of the entire chromosome rather than a partial arm deletion.
• Monosomy of chromosome 19, indicating a complete loss of one copy of chromosome 19.
• Relative deletion ratio of 1p/1q below the established diagnostic threshold (typically less than 0.85).
• Relative deletion ratio of 19q/19p below the diagnostic threshold, confirming 19q loss.
• Normal signal ratio (around 1.0) for both chromosome 1 and chromosome 19 probes.
• Heterogeneous tumor cell populations with variable deletion patterns across different tumor areas.
• Segmental deletions of the 1p36 region, which may differ from the complete arm deletion seen in classic oligodendrogliomas.
• Segmental deletions of the 19q13 region.
• High-level amplification of reference loci, indicating complex chromosomal rearrangements.
• Balanced translocation events that do not result in a net loss of genetic material.
• Low tumor cellularity in the sample, which may limit the diagnostic sensitivity of the FISH assay.
• Presence of necrosis or artifactual signal loss, requiring careful pathological correlation.
• Polyploidy, where multiple copies of the entire genome are present within the tumor cells.
• Co-existing chromosomal gains or losses that suggest genomic instability.
• Normal diploid control signals in adjacent non-neoplastic brain tissue.
• Technical adequacy of the hybridization process, confirming reliable probe binding.
• Signal patterns consistent with an IDH-mutant, 1p/19q-codeleted oligodendroglioma, CNS WHO grade 2.
• Signal patterns consistent with an IDH-mutant, 1p/19q-codeleted oligodendroglioma, CNS WHO grade 3 (anaplastic).

Turnaround Time and Report Access at Dr. Essa Lab

Dr. Essa Lab is committed to providing rapid and highly accurate diagnostic results. Given the complexity of molecular cytogenetics and the meticulous nature of Fluorescence In Situ Hybridization (FISH), the turnaround time for the 1P19Q /DEL Oligodendroglioma by fish (AKU) is typically between 7 to 10 working days. This timeframe ensures that the tissue undergoes optimal processing, hybridization, and detailed microscopic evaluation by expert molecular pathologists. Once the report is finalized, patients and their referring physicians can access the results easily. Dr. Essa Lab offers a secure online reporting portal on their official website, where reports can be viewed and downloaded using the patient’s lab ID and password. Additionally, patients receive real-time SMS notifications when their reports are ready, and physical copies can be collected from any of the numerous Dr. Essa Lab collection centers across Karachi and other cities in Pakistan.

1P19Q /DEL Oligodendroglioma by fish (AKU) Findings Overview

Structure / Parameter Evaluated	Normal Findings	Possible Abnormal Findings
1p36 Locus Status	Two signals per nucleus (diploid)	Single signal per nucleus (deletion) or multiple signals (gain/polysomy)
19q13 Locus Status	Two signals per nucleus (diploid)	Single signal per nucleus (deletion) or multiple signals (gain/polysomy)
1p/1q Signal Ratio	Ratio close to 1.0 (normal)	Ratio less than 0.85 (indicates 1p deletion)
19q/19p Signal Ratio	Ratio close to 1.0 (normal)	Ratio less than 0.85 (indicates 19q deletion)
Co-deletion Status	Both loci intact (no co-deletion)	Concurrent deletion of both 1p and 19q loci
Chromosome 1 Ploidy	Diploid (two reference signals)	Monosomy (one signal) or Polysomy (three or more signals)
Chromosome 19 Ploidy	Diploid (two reference signals)	Monosomy (one signal) or Polysomy (three or more signals)
Tumor Cell Cellularity	Adequate tumor cells (greater than 50% cellularity)	Low cellularity (less than 30%), potentially leading to inconclusive results

Note: Diagnostic findings should always be interpreted by a qualified healthcare professional together with the patient’s symptoms, medical history, physical examination, laboratory investigations, previous imaging studies, and other relevant clinical information. Additional investigations or specialist consultation may be recommended depending on the findings.

Why Choose Dr. Essa Lab for 1P19Q /DEL Oligodendroglioma by fish (AKU)?

• Pioneering Diagnostic Excellence: Dr. Essa Lab has been a trusted name in pathology and diagnostic services in Pakistan since 1987.
• Advanced Molecular Pathology Department: Equipped with state-of-the-art cytogenetic and molecular testing facilities, including high-resolution fluorescence microscopy.
• Expert Pathologists: Reports are analyzed and signed off by highly qualified, fellowship-trained molecular pathologists and cytogeneticists.
• Rigorous Quality Control: Dr. Essa Lab adheres to strict international quality standards and participates in external quality assurance programs.
• Convenient Online Report Access: Patients and oncologists can instantly download reports through a secure online portal or mobile application.
• Extensive Network: With numerous collection centers across Karachi and nationwide, sample submission is highly convenient.
• Compassionate Patient Care: A dedicated support team is available to assist patients with sample requirements, coordination, and queries.
• Affordable and Accessible Testing: Offering advanced molecular diagnostics at competitive pricing to ensure accessibility for all patients.