Health Desk
Sandeep Dhand
Nutritionist And Health Educator
Introduction
Genetics is the study of how traits are passed from parents to children. Our body is made up of trillions of cells, and each cell carries a set of instructions called genes. These genes decide how we look, how our body functions, and even how likely we are to get certain diseases.
Some diseases are caused by a single faulty gene, while others happen because of a combination of genes and lifestyle factors like diet, pollution, and stress. In this article, we will explore how genes and chromosomes influence diseases, what are chromosomal disorders, how diseases are inherited through unifactorial and multifactorial inheritance, and how we can prevent and manage genetic disorders.
- Understanding Genes and Chromosomes
What Are Genes?
Genes are small segments of DNA (Deoxyribonucleic Acid) found inside the nucleus of every cell. Each gene acts like a set of instructions that tells the cell what to do — such as how to build proteins, enzymes, and other important molecules that keep our body healthy.
Each person has about 20,000 to 25,000 genes. Some genes decide visible traits like hair color or height, while others control body processes like metabolism or immunity.
What Are Chromosomes?
Chromosomes are thread-like structures made of DNA and proteins. They carry genetic information in a tightly packed form. Humans normally have 46 chromosomes, arranged in 23 pairs:
22 pairs of autosomes (control body traits)
1 pair of sex chromosomes (XX in females, XY in males)
Half of these chromosomes come from the mother and half from the father.
If something goes wrong during the formation or copying of these chromosomes, it can lead to genetic disorders.
- The Connection Between Genetics and Diseases
Every disease has two types of causes:
- Genetic causes — due to changes (mutations) in genes or chromosomes.
- Environmental causes — such as infections, poor diet, smoking, or pollution.
Sometimes, both types of factors combine to cause illness. For example, diabetes can run in families, but unhealthy eating and lack of exercise can trigger it.
Types of Genetic Changes
Mutation: A small change in the DNA sequence that can alter how a gene works.
Deletion: A part of the gene or chromosome is missing.
Duplication: A part of the DNA is repeated.
Translocation: A section of one chromosome attaches to another.
These changes can disturb normal body functions and cause disease.
- Chromosomal Disorders
When chromosomes are not normal in number or structure, it leads to chromosomal disorders.
They are divided into two main categories:
A. Numerical Chromosome Abnormalities
This happens when a person has too many or too few chromosomes.
- Down Syndrome (Trisomy 21)
Caused by an extra copy of chromosome 21.
Features: mental delay, flat facial profile, short neck, weak muscles, and heart problems.
It is one of the most common chromosomal disorders.
- Turner Syndrome (45, X)
Found only in females who have one X chromosome missing.
Features: short height, infertility, heart defects, and swollen hands or feet.
- Klinefelter Syndrome (47, XXY)
Found only in males who have one extra X chromosome.
Features: tall height, small testes, low testosterone, learning difficulties, and infertility.
B. Structural Chromosome Abnormalities
These occur when the chromosome breaks or rearranges.
- Cri-du-chat Syndrome
Caused by deletion of part of chromosome 5.
Children have a high-pitched cry (like a cat), mental delay, and small head.
- Philadelphia Chromosome
Formed when chromosomes 9 and 22 exchange parts.
Leads to chronic myeloid leukemia (CML) — a type of blood cancer.
- Unifactorial (Single-Gene) Inheritance
A unifactorial disorder happens due to a defect in one single gene.
These are also called Mendelian disorders, because they follow the rules of inheritance first explained by Gregor Mendel.
Types of Single-Gene Disorders
A. Autosomal Dominant Disorders
Only one copy of a defective gene from either parent can cause disease.
Example:
Huntington’s Disease: Causes nerve degeneration in the brain.
Marfan Syndrome: Affects connective tissue, leading to tall height and heart problems.
Familial Hypercholesterolemia: Causes very high cholesterol levels.
B. Autosomal Recessive Disorders
Both parents must pass the defective gene for the child to be affected.
Example:
Cystic Fibrosis: Causes thick mucus in lungs and digestive problems.
Sickle Cell Anemia: Changes the shape of red blood cells, causing pain and anemia.
Thalassemia: Reduces hemoglobin production.
C. X-linked Disorders
Gene defect is carried on the X chromosome.
Mainly affects males (as they have only one X chromosome).
Example:
Hemophilia: Blood doesn’t clot normally.
Duchenne Muscular Dystrophy: Causes muscle weakness.
Color Blindness: Inability to distinguish certain colors.
- Multifactorial (Polygenic) Inheritance
Many common diseases are caused by a combination of several genes and environmental factors.
These are called multifactorial disorders or polygenic diseases.
Examples of Multifactorial Diseases
Diabetes Mellitus
Hypertension
Obesity
Coronary Heart Disease
Asthma
Certain Cancers (like breast or colon cancer)
These conditions often run in families, but lifestyle plays a big role.
For example, if your parents have diabetes, you have a higher chance — but regular exercise and a healthy diet can help prevent it.
- How Genetic Diseases Are Diagnosed
A. Family History
Doctors study the medical history of several generations to find patterns.
B. Genetic Testing
Modern lab tests can identify specific gene mutations.
C. Prenatal Testing
Tests like amniocentesis and chorionic villus sampling (CVS) can detect chromosomal abnormalities before birth.
D. Newborn Screening
Soon after birth, babies are tested for certain genetic conditions like phenylketonuria (PKU) or congenital hypothyroidism, so treatment can start early.
- Prevention of Genetic Diseases
Although not all genetic disorders can be avoided, several steps can reduce the risk:
A. Genetic Counseling
Helps families understand genetic risks before planning a baby.
Provides information about testing and possible treatments.
B. Prenatal Diagnosis
Detects chromosomal or gene defects early in pregnancy.
Parents can make informed choices.
C. Carrier Screening
Identifies people who carry defective genes but show no symptoms.
D. Avoiding Consanguineous Marriages
Marriages between close relatives increase the risk of recessive diseases.
E. Healthy Lifestyle
For multifactorial diseases, balanced diet, physical activity, and avoiding smoking or alcohol are important.
F. Early Treatment and Support
Regular medical check-ups and therapy help in managing symptoms and improving quality of life.
- Diet and Lifestyle for Genetic Health
Although genes cannot be changed easily, lifestyle choices can influence gene expression — a concept called epigenetics.
Healthy habits can reduce the impact of genetic risks.
Healthy Diet Tips
Eat fresh fruits and vegetables daily for vitamins and antioxidants.
Include whole grains, nuts, and legumes for fiber and energy.
Avoid processed foods, excess sugar, and trans fats.
Drink plenty of water and stay hydrated.
Limit alcohol and tobacco use.
Lifestyle Tips
Get regular exercise (at least 30 minutes a day).
Maintain a healthy weight.
Get adequate sleep (7–8 hours per night).
Manage stress with meditation or yoga.
Go for regular health check-ups if genetic diseases run in your family.
- Modern Advances and Future Prospects in Genetics
The future of genetic medicine is very bright.
Scientists are making great progress in detecting, treating, and even curing genetic disorders.
A. Gene Therapy
Involves inserting a healthy gene to replace a defective one.
Used in treating diseases like thalassemia and certain immune disorders.
B. CRISPR Gene Editing
A new technology that allows scientists to cut and repair DNA precisely.
It can correct mutations before they cause disease.
C. Personalized Medicine
Doctors can now design treatment based on a person’s genetic makeup.
It helps in choosing the best medicine with fewer side effects.
D. Stem Cell Therapy
Healthy stem cells can replace damaged ones.
Useful in treating blood diseases and genetic disorders.
E. Public Awareness
Educating people about genetic diseases helps in early diagnosis and better prevention.
- The Role of Nutrition and Health Education
Educating people about nutrition, healthy habits, and genetic awareness can reduce disease risk.
Health educators and nutritionists play an important role by:
Promoting healthy diets.
Encouraging genetic testing when needed.
Helping families understand how lifestyle interacts with genes.
- Ethical and Social Issues in Genetics
While genetic science is advancing rapidly, it also raises ethical questions:
Should parents choose their child’s traits?
How should genetic data be stored or shared?
What about discrimination based on genetic information?
Countries are developing strict bioethics laws to ensure genetic research is used responsibly.
- Summary
Genes and chromosomes control body structure and function.
Mutations or chromosomal errors can lead to disease.
Single-gene disorders follow clear inheritance patterns.
Multifactorial diseases result from gene–environment interaction.
Prevention through genetic counseling, testing, and healthy lifestyle is key.
Modern tools like gene therapy and CRISPR bring new hope for the future.
- Conclusion
Genetic factors play a crucial role in health and disease.
By understanding how genes work, we can detect diseases early, prevent complications, and promote healthier generations.
Genetic counseling, awareness, nutrition, and lifestyle improvement are essential for a world with fewer genetic disorders.
The future of medicine lies in genomic science, personalized care, and education that empowers people to take control of their genetic health.