H-excess A1 and Aint variants among the Bulgarian population

During the investigation of the subgroups of 45,895 A blood group persons, H-excess A1 and Aint variants were found in 0.359%. These variants were subdivided into three categories provisionally named A1H, A1Hint and AintH according to their most typical isoserological characteristics. The results of genealogical investigation are presented. An attempt was made to explain the existence of these atypical subgroups.