Renal transplantation in a patient with hereditary deficiency of the second component of complement.

The HLA haplotype A 10,B18 has been associated with hereditary deficiency of the second component of complement(C2). In an effort to detect individuals homozygous for C2 deficiency, a thorough audit of HLA serotyping results in 3,100 individuals was performed, and a single patient homozygous for the A10, B18 haplotype was identified. Detailed complement studies in this patient's serum and plasma revealed previously undetected selective absence of C2 antigen and haemolytic activity, and a hereditary basis for this deficiency was indicated by half-normal levels of C2 haemolytic activity in both of his children. The patient was of special interest in that he had previously developed renal failure which was treated by cadaver kidney transplantation. C2 antigen was undetectable in serum and plasma samples taken prior to and up to 9 months following transplantation. This experience suggests that HLA serotyping can be a valuable screening technique for the detection of individuals with C2 deficiency, and that renal transplantation does not reconstitute normal levels of C2.