Rhesus Rh system 1-2

1940 discovered by landsteiner and Weiner. People who possess RH factor are called RH positive and those who lack are called RH negative. Independent of abo blood group and MNS blood group system.

Cde system. D = dominant/positive. d = negative

Role unclear. 

Rh -ve are : Mongoloids have rear 1.5%. whites have very high 15%. Negros have 5 to 8%. India 1-8% rh negative.

It may cause erythroblastosis fetalis if the mother is RH negative and the child is RH positive. It may transfer antibodies to the child during birth and cause cerebral palsy liver jaundice disease or death after birth and even after birth antibodies may attack. 

Women are given injection to avoid antibodies during birth.