Unit
- DNA Structure and Function: The human genome consists of approximately 3 billion base pairs organized into 23 chromosome pairs. DNA encodes genes that direct protein synthesis and regulate cellular processes. In cancer, alterations in DNA sequence or structure disrupt normal cell growth control.
- Gene Mutations: Mutations are permanent changes in DNA sequence that can be inherited (germline) or acquired (somatic). Point mutations, insertions, deletions, and copy number variations all contribute to cancer development when they affect key regulatory genes.
- Oncogenes: Proto-oncogenes are normal genes that promote cell growth and division. When mutated or overexpressed, they become oncogenes that drive uncontrolled proliferation. Common examples include
RAS,MYC, andEGFRfamilies. - Tumor Suppressor Genes: These genes normally restrain cell growth and promote DNA repair or apoptosis. Loss-of-function mutations in tumor suppressors such as
TP53,RB1, andBRCA1remove critical brakes on cell division. - Genomic Instability: Cancer cells often exhibit increased mutation rates due to defects in DNA repair pathways. This instability accelerates the accumulation of genetic changes that drive tumor evolution and therapeutic resistance.
- Clonal Evolution: Tumors arise from a single mutated cell and accumulate additional mutations over time, leading to heterogeneous populations of cancer cells. This Darwinian process underlies treatment failure and metastasis.
- Epigenetic Alterations: Changes in gene expression without DNA sequence changes, such as DNA methylation and histone modification, are common in cancer. Epigenetic silencing of tumor suppressor genes can be as impactful as genetic mutations.
- Cancer Genome Landscapes: Large-scale sequencing projects like The Cancer Genome Atlas have cataloged recurrent mutations across cancer types. Understanding these landscapes helps identify new therapeutic targets and biomarkers.
- DNA Repair Pathways: Cells employ multiple mechanisms to repair DNA damage, including base excision repair, nucleotide excision repair, and mismatch repair. Defects in these pathways, such as in Lynch syndrome from
MLH1orMSH2mutations, increase cancer risk by allowing mutations to accumulate. - Telomere Dysfunction: Telomeres protect chromosome ends from deterioration and fusion. In cancer, telomerase is often reactivated to maintain telomere length, enabling unlimited replicative potential. Shortened telomeres can also trigger genomic instability through breakage-fusion-bridge cycles.
- Chromosomal Rearrangements: Large-scale structural alterations such as translocations, inversions, and deletions can create fusion genes or disrupt regulatory elements. The Philadelphia chromosome t(9;22) producing
BCR-ABL1in chronic myeloid leukemia is a classic example of a driver rearrangement. - Non-coding RNA in Cancer: MicroRNAs and long non-coding RNAs regulate gene expression at the post-transcriptional level. Dysregulation of non-coding RNAs can promote oncogenesis by affecting cell cycle, apoptosis, and metastasis. For instance, the
miR-17-92cluster is often overexpressed in various cancers.
Scope of Practice
Role: Cancer Genetics Program Manager
Within scope:
- Coordinate genomic testing workflows including sample tracking and result reporting
- Maintain up-to-date knowledge of genomic technologies and variant classification updates
- Develop standard operating procedures for handling genetic information
- Facilitate communication between laboratory, clinical, and administrative teams
- Ensure compliance with regulatory requirements such as CLIA and HIPAA
Outside scope:
- Interpretation of genetic test results for clinical decision-making
- Providing direct patient counseling on genetic risks or treatment options
- Prescribing or recommending targeted therapies based on genomic findings
- Making independent clinical judgments about patient care pathways
- Performing laboratory testing or variant analysis procedures
Quick Revision
- The human genome provides the blueprint for cellular function; cancer arises from mutations in oncogenes and tumor suppressor genes.
- Genomic instability and clonal evolution drive tumor progression and heterogeneity.
- Epigenetic changes also contribute to cancer without altering DNA sequence.
- Cancer Genetics Program Managers coordinate testing workflows and maintain regulatory compliance but do not interpret results or make clinical decisions.
Disclaimer
Educational use only. Not intended for practical surgery, incisions, or other surgical procedures. It does not qualify you to perform physical operations.