The human body consists of trillions of cells, the basic building blocks of any complex organism. These cells work together to form organs like the heart, liver, and skin.

For cells to function properly, they must have certain traits, such as the ability to divide, remain in their designated locations, and avoid overcrowding their neighboring cells.

What Are Genes?

Genes are segments of DNA found inside each cell, providing instructions for creating the proteins the cell needs to operate. Every gene contains the blueprint to build a specific protein, each with a unique function. Some genes code for proteins that help cells grow and divide, while others maintain control over cell growth.

Genes and Chromosomes

Genes are located within chromosomes, long strands of DNA within each cell. Each chromosome contains many genes. Most human cells have 23 pairs of chromosomes—one chromosome from each pair is inherited from the mother, and the other from the father. This explains why children often resemble their parents and may inherit certain genetic traits, including susceptibility to certain diseases.

Gene Expression and Specialization

Dear Lykkers, though all cells have the same genetic makeup, each cell activates only the genes it needs. By turning some genes on and others off, cells specialize to perform specific roles, like becoming muscle or bone-cells. Some genes remain active continuously to maintain basic functions, while others are deactivated after fulfilling their purpose but can be reactivated if necessary.

Changes in Genes

While our genes are generally similar, individual variations make each person unique. The ‘code’ for each gene consists of nucleotides, the building blocks of DNA. These nucleotides (A, T, G, and C) combine to form genes, dictating the production of specific proteins.

Gene Variants and Mutations

Gene variants, or mutations, occur when changes in the nucleotide sequence happen. These changes can range from minor alterations with no visible effect on the protein, to significant changes that render the protein ineffective.

Types of Gene Variants:

Minor Effect: No noticeable change in protein function.

Moderate Effect: A small change in the protein, reducing its efficiency.

Severe Effect: A mutation that results in a nonfunctional protein.

Gene variants that impact protein function can affect cells and the entire body. These changes may lead to visible differences, such as eye color, or contribute to diseases like cancer.

Inherited vs. Acquired Gene Mutations

Gene mutations can be inherited or acquired.

Inherited Gene Mutations:

These mutations are passed from parents and present in the first cell after fertilization. Since every cell originates from this first cell, inherited mutations are found in all body cells and can be passed down to future generations. This type of mutation is referred to as a germline or hereditary mutation. Inherited mutations can make it easier for other mutations to occur, potentially leading to conditions like cancer at an earlier age.

Acquired Gene Mutations:

Acquired mutations happen after birth and arise in a single cell. These mutations can affect the offspring of the mutated cell but are not passed to future generations. Acquired mutations can result from DNA damage caused by factors like radiation or chemicals, or from random errors during cell division. These mutations accumulate over time, explaining why the risk of cancer increases with age.

Acquired mutations are a more common cause of cancer than inherited mutations.

Other Ways Gene Activity Can Change

Apart from genetic mutations, changes in gene activity can also affect cell growth and division. These changes don't involve altering the DNA sequence but instead regulate the activation or deactivation of genes. These regulatory changes are known as epigenetic changes.

Types of Epigenetic Changes:

DNA Methylation: A methyl group is added to DNA, preventing the gene from producing its protein. Removal of the methyl group reactivates the gene.

Histone Acetylation: Proteins called histones bind to DNA. Adding acetyl groups to histones can activate genes, while removing them can turn the genes off.

RNA Interference: RNA molecules can block or degrade messenger RNA (mRNA), preventing gene expression.

Drugs targeting these epigenetic mechanisms are being developed to treat cancer by reactivating genes that control cell growth.

How Gene Changes Affect Cancer Risk

Some genes control cell growth, division, DNA repair, and cell death. When these genes malfunction, it can increase the risk of cancer.

Oncogenes and Tumor Suppressor Genes:

Oncogenes are genes that promote cell growth. Mutations can make these genes more active, causing uncontrollable cell proliferation.

Tumor Suppressor Genes regulate cell division and death. Mutations that deactivate these genes can lead to uncontrolled cell growth.

DNA Repair Genes help correct DNA mistakes. When these genes are mutated, the accumulation of DNA errors can result in uncontrolled cell growth.

Typically, multiple mutations are needed for a cell to become cancerous.

Other Risk Factors:

Some gene variants may not directly cause cancer but can increase susceptibility to it. For example, gene changes that impair the body’s ability to process toxins from tobacco can increase the risk of lung cancer among smokers. Additionally, genetic factors affecting body weight can indirectly influence cancer risk.

Gene variants and mutations are common, and their effects can have significant impacts on our health. Understanding how changes in genes affect cell function, cancer risk, and overall well-being can lead to improved cancer prevention and treatment strategies.