title: Weak A phenotypes possibly caused by mutation.
abstract: A family is described in which an apparent Ay phenotype was transmitted through 2 generations. We favor a mutation of the A allele as the most likely cause of the phenotype. Activities of the serum A-gene-specified transferase were not detected in any of the 3 family members with the Ay phenotypes.
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000328:Adult; D002648:Child; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D012463:Saliva / Q000276:immunology
chemical_list: D000017:ABO Blood-Group System