ABSTRACT:Tissue typing performed on the lymphocytes of 41 Patients, including: 23 patients with ichthyosis (15 of autosomal dominant and 8 of the x‐linded variety; 8 patients with tuberous sclerosis (epiloia); and 10 patients with acroder‐matitis enteropathica (AEP). In adddition, tissue typing was performed for a control group of 80 healthy unrelated subjects of the same ethnic origin as the patients. A significant increase of A2antigen or its crossreacting antigen A28was detected among the three diseases studied. A significant increase of HLA‐A2antigen was found in autosomal dominant ichthyosis, while the x‐linked variety showed significant association with HLA‐Cw2. A significant association with HLA‐A28antigen was noticed in both epiloia and AEP. The suggested mechanisms of such association may be refferred to as incidental genetic linkage with mutants causing disease or