my blood group has changed when tested this month while giving blood to someone. they re laughing saying it can never. am a biotech student . and i ve some 20 reports from the birth that i had done. i ve all the evidences. am married now. and my husband is O+ and i was O+ too as we had checked after marriage too. my mom is O+ and my dad A+.. now mine is A+. even my dad has got same case over the time. he too has some 100 reports among which the previous from birth was O+ and now its A+... what is this mutation exactly.. please revert back as soon as possible.