The HLA antigens and ABO blood groups in an American Black population with mitral valve prolapse

A total of 42 American Black patients with mitral valve prolapse and 194 healthy individuals of similar ethnic background were tested for the distribution of various HLA antigens and ABO blood groups. The most significant result was an increased frequency of Bw35 in patients (74%) as compared with controls (39%), with a P value of less than 0.0001; the relative risk was 4.45.