While some of these diseases are incurable or even genetic, the provide a higher resistance to the person to other diseases.

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1. Sickle cell anaemia and malaria

Carriers of the sickle cell anaemia gene have proven to be more resistant to malaria. This is because of presence of lower haemoglobin causing more carbon monoxide to be present in blood which plays a critical role in preventing malaria.

2. Tay-Sachs and tuberculosis

The Tay-Sachs gene contains enzymes that make it resistant to the bacteria that causes Tuberculosis. . Tay-Sachs disease destroys neurons in the brain and spinal cord.

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3. Cystic Fibrosis and cholera

People with cystic fibrosis have been seen to survive the most virulent strain of cholera.

Cystic fibrosis is a disease that affects the lungs and digestive tract. It causes mucus to build up in the lungs and intestines. It blocks digestive enzymes from reaching the food. Cystic fibrosis blocks chloride channels, keeping fluids in.

4. Congenital Disorder Of Glycosylation 2b And Viral Infections

CDG-IIb has been shown to prevent viral infections such as HIV, herpes, Hepatitis C and the flu.

It is a rare disease that causes prevention of viruses by the presence of an enzyme. The enzyme prevents viruses present in the body from reproduction.

CDG-IIb patients don't have proper cell glycosylation- the process by which sugars are chemically attached to proteins to form glycoproteins.

CDG is a very serious condition which can lead to sometimes fatal, malfunction of several different organ systems (especially the nervous system, muscles, and intestines) in affected infants.

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