This Word Means: Haemophilia

Haemophilia is caused by a defect in the X chromosome.

WEDNESDAY, April 17 is World Haemophilia Day. Haemophilia is a medical condition, mostly inherited, in which the ability of blood to clot is severely reduced, so that even a minor injury can cause severe bleeding. Because of the genetics involved in the way the sex of a child is determined, men are more vulnerable to haemophilia than women.

Boys and girls

The sex of an inpidual is determined by a pair of "sex chromosomes" (a chromosome is a DNA molecule that contains genetic information). Females are identified with an XX pair of sex chromosomes, and males with an XY pair. When an X chromosome from the mother pairs up with the father's X chromosome, the offspring is XX (female); when an X chromosome from the mother pairs up with the father's Y chromosome, the offspring in XY (male).

Haemophilia is caused by a defect in the X chromosome. If a girl is born with one defective X chromosome, her other X chromosome can compensate for it. In such a case, she is a carrier of haemophilia but will not suffer from the condition herself. Only if both her X chromosomes are defective will she suffer from haemophilia herself. On the other hand, if a boy is born with a defective X chromosome, he does not have the second X chromosome to compensate for it, and will suffer from haemophilia. That is the reason haemophilia is more common among men.

'Royal disease'

Britain's Queen Victoria (1819-1901) is the world's most widely known carrier of haemophilia. From her, the condition spread among a number of European royal families, which is why haemophilia was once known as the "royal disease". Victoria passed on a defective X chromosome to three of her children. Her son Prince Leopold died at age 30 as a result of loss of blood after injury. Leopold's daughter, Princess Alice of Albany, was a carrier whose son inherited haemophilia and died at age 21.

Among Victoria's children, the other two who inherited a defective X chromosome were daughters. Both Princesses Alice and Beatrice were carriers who passed on haemophilia to several other royal families, notably those of Spain and Russia. One of these cases - that of Alice's grandson Prince Alexei (1904-18) of Russia - changed the course of history. Alexei's mother Alexandra relied on the monk Rasputin to cure her son, and many historians believe that Rasputin's closeness to the royal family hastened the Russian revolution of 1917. Alexei did not die of haemophilia but was executed along with others of his family. A study of his remains, published in Science magazine in 2006, established that the young prince did suffer from haemophilia.

Haemophilia in India

It is a rare disorder worldwide - one type, called Haemophilia A, occurs in about 1 in 5,000 births, while Haemophilia B is even rarer at about 1 in about 20,000 births. A vast number of cases, however, are believed to go unreported, particularly in India. According to the World Federation of Haemophilia's Annual Global Survey 2017, released in October 2018, there were over 1.96 lakh persons living with haemophilia across the world in 2017. In the country-wise data, India emerges with the highest count at nearly 19,000. On Tuesday, experts quoted by PTI estimated that 80% cases go unregistered, so that the actual count is close to 2 lakh.