Q: I am 19 years old female with B negative blood group. I have heard from many people that having B negative as one's blood group isn't good. Someone also told me that it can lead to cancer. And that it is very rare. Is all this true?

A:There are more than 20 blood group systems known which are shared by human beings, and some even with other primates, like monkeys. We inherit them from our parents and environment cannot influence them. The distribution pattern of specific blood group types is complex and it differs in different geographical areas related to the evolutionary history of man. Blood group B has highest prevalence in Central Asia (including India) and some regions of Africa and lowest in the Americas and Australia. Overall in the world, B is the rarest ABO blood allele with only 16% of people having it. A lot of researchers have looked for associations between ABO type and almost every possible disease and there are reports of various blood groups being linked to diseases ranging from cancer (gastro-intestinal, breast, salivary glands, skin etc.) to heart disease and gastro-intestinal disorders. They have also been related to disorders like von Willebrand disease, severity of dengue fever or SARS, leishmaniasis, giardiasis, bone density, colour blindness, mental disorders etc. but not one single disease is exclusive to a particular blood group type. Yes, the frequency of B-negative group is less in India but please get this notion out of your mind that some blood groups are 'good' while others are 'bad' as there is no such thing in human biology or genetics, as diseases are not predetermined by blood types.