The Diego factor in a Puerto Rican family: a case of anti-Diego.

INTRODUCTION T HE DIEGO ( Di’ ) blood factor, first described by Levine,1’27 and Layrisse2’3 has been extensively studied.22#{176} It is serologically distinct from other known blood factors,3 does not appear to be linked to any of them1 and may represent a separate blood group system.”12 The factor is of anthropological interest because of its presence in most North and South American Indian tribes267”0 4”5,16,’7’8 and in orientals. ”4 It has even been used as a marked to trace Mongoloid racial migrations.’#{176} The Diego factor is absent in Negroes,8’2#{176} Australian aborigines,2’ Polynesians22’23 and Caucasians except where Amerindian or Mongoloid admixture may have taken place. Its allele ( Dib ) , if it exists, has not yet been discovered. Three cases of anti-Diego have been described.325’27 This paper presents a fourth with unusual features.