A new antigen, McCa (McCoy), and its relationship to Kna(Knops).

@article{Molthan1978ANA,
  title={A new antigen, McCa (McCoy), and its relationship to Kna(Knops).},
  author={L Molthan and J P Moulds},
  journal={Transfusion},
  year={1978},
  volume={18 5},
  pages={566-8}
}
The antigen McCa is detected in 98.5 and 96.7 per cent of the American Caucasian and Negro populations respectively. In population studies with anti-McCa and anti-Kna, a strong association was demonstrated between the two antigens, with 53 per cent of McC(a-) sample being Kn(a-) compared with a reported frequency for Kn(a-) of only 0.19 per cent.