Most blood type falls into the four basic blood groups: A B O and AB. However within these there are 400 other groups or variable factors that further determine the exact blood type by identifying specific characteristics of blood. Hence people with rare blood groups face a daunting task to find donors with matching rare blood types. As a step to facilitate availability of rare blood donors Department of Transfusion Medicine Medanta – The Medicity has put together 'Rare blood donor registry' with the database of 450 active 'completely phenotyped' rare blood donors. Speaking at the felicitation event Dr Naresh Trehan