How sickle cell gene protects against Malaria

A US team has found a way in which the gene that causes sickle cell disease is protected from the ravages of malaria.

People who develop sickle cell disease have inherited from both parents defective versions of a gene for haemoglobin, the ironcontaining protein in red blood cells that transports oxygen from the lungs to tissues in the body.

Their red blood cells, instead of being disc-like, turn crescent shaped. Such individuals can suffer from anaemia, episodes of pain, serious infections and even organ damage.

Those with the defective gene from only one parent usually escape such health problems.

However, these individuals too get milder forms of malaria rather than the life-threatening kind that can afflict people with the normal gene. This survival advantage has resulted in the faulty gene occurring at higher frequencies in malaria-endemic parts of the world.

At one stage during their complicated life cycle, the singlecelled Plasmodium parasites, which cause malaria, invade red blood cells and proliferate there, feeding on haemoglobin.

In a paper published recently in the journal Cell Host & Microbe, Jen-Tsan Chi and his colleagues at the Duke University Medical Centre in the U.S. noted that short strips of the genetic material RNA, known as microRNA (miRNA), were found at enhanced levels in the red blood cells of people with the sickle cell gene.

Like genes (which are needed to produce proteins), the genetic information to make miRNA too is carried in the DNA of organisms.