The highest rates of the Jr(a) negative blood type have been reported in Japan, where its prevalence ranges from 1 in 60 in the Niigata region to 1 in 3800 in the Tokyo region. Additionally, a number of cases have been documented in European Romani populations. The Jr(a) negative blood type is very rare in America: a study of 9,545 Americans failed to identify any Jr(a) negative individuals.
Junior blood group system
Augustine blood group system
Sid blood group system
Vel blood group
Rh blood group system
P1PK blood group system
Lan blood group system
Indian blood group system