Ever wondered why diseases occur? Here’s the answer
Since our childhoods, we all have fallen ill or come across a person who is suffering from what we call a disease. Although our perception of diseases may include a few, that we have encountered or contracted sometime, but there are hundreds of thousands of them. In this article, we mention their basic classification, some of the important examples of common diseases and their causes.
Disease means a physically or psychologically abnormal condition that leads to improper functioning of an organism’s body. Diseases can be broadly classified into the following categories based on the type of their root cause:
- Infectious diseases
- Lifestyle diseases
- Genetic diseases
- Deficiency diseases
Infectious diseases and their causes
Infectious diseases include those diseases that are caused by the entry of a foreign entity such as a pathogen(amoeba, bacteria, etc) or an allergen(pollen, dust particles). The foreign entity alters the normal physiology of the human body. Pathogens exploit the cells and tissues of the host for nutrition and reproduction. Common examples include:
- Malaria (caused by Plasmodium parasite carried by female Anopheles mosquitoes)
- Hepatitis C (caused by the hepatitis C virus)
- Dengue Fever (caused by a family of viruses transmitted by Aedes mosquitoes)
- Tuberculosis (caused by bacteria called Mycobacterium tuberculosis)
- Cholera (caused by the bacterium Vibrio cholera)
Lifestyle diseases and their causes
Lifestyle diseases include those diseases whose occurrence is associated with the habits of a person or a group. This may be due to excessive consumption of food with high calories or those that contain fatty acid molecules or cholesterol. Common examples include:
- Cardiac diseases
- Type 2 diabetes
- Diseases associated with smoking (eg-Chronic obstructive pulmonary disease)
- Diseases associated with Alcohol (eg-Alcoholic liver cirrhosis)
- Drug abuse (Paranoia, Increased heart rate, and blood pressure)
Genetic diseases and their causes
A medical condition caused by an abnormality in the genetic makeup of the body. Changes can occur in the number of chromosomes (such as trisomy or monosomy of a chromosome) or a point mutation in the DNA sequence. Common examples include:
- Down’s syndrome – caused by the presence of all or part of the third copy of chromosome 21
- Phenylketonuria(PKU) – occurs due to mutations in the PAH gene, which results in low levels of the enzyme phenylalanine hydroxylase
- Sickle cell anemia – occurs due to a single nucleotide mutation f the β-globin gene, resulting in glutamic acid being substituted by valine
- Tay–Sachs disease – occurs due to a genetic mutation in the HEXA gene on chromosome 15
- Cystic fibrosis – caused by mutations in both copies of the gene for the cystic fibrosis transmembrane conductance regulator (CFTR) protein
- Turner’s syndrome – Caused by partly or completely missing X chromosome resulting in XO condition
Deficiency diseases and their causes
The cause of these type of diseases is the absence or presence in very low quantities of a particular vitamin or mineral essential for the body. Demographically, these type of diseases are found in poor households, where people are not able to afford basic amenities. These diseases include:
- Calcium related – Osteoporosis, Rickets, Tetany.
- Iodine deficiency related – Goiter.
- Selenium deficiency related – Keshan’s disease.
- Iron deficiency related – anemia.
- Zinc related – Growth retardation.
- Thiamine (Vitamin B1) related – Beriberi.
- Niacin (Vitamin B3) related – Pellagra.
- Vitamin C related – Scurvy
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