Kramer and colleagues (13,14) reported a marked reduction in the frequency of C4QO allele in old Hungarian groups and concluded that individuals carrying this allele, especially males, may have considerably shorter life expectancy than individuals lacking a silent gene at this locus. These studies prompted us to evaluate class III and C3 alleles in healthy Italian aged people and centenarians, and we found that the allele frequency distribution of C4, BF, and C3 in the cohorts under study do not show any statistical difference. In the same direction, the preliminary data on the DNA polymorphism of the C4/21-0H region are of limited value because of the small number of studied samples (10 centenarians). The slight increase of C4BQO allele in centenarians suggests that C4BQO is not a negative survival factor. It is important to note that the oldest person in our cohort was a C4BQO heterozygote (female, 107 years old, haplotype = A3BlBQOSF). Females outnumber males 5:1 in the oldest cohort, but the distribution of alleles does not seem to beStudies in Man: The Senior Protocol. Dev.;  ;:  -  " Awdeh ZL, Alper CA. Inherited structural polymorphism of the fourth component of human complement. Proc Natl Acad Sci USA;  ;: &-  Sim E, Cross SJ. Phenotyping of human complement component C. Biochem.;  ;:  -  Zhang WJ, Kay PH, Cobain TJ, Dawkins RL. Callotyping on plasma or serum: application to routine laboratories. Hum Immunol.;  ;:  -  Kramer J, Gyodi E, Fust G. Usefulness of densitometry in typing human complement component C. Immunogenetics.;  ;:  -  Rittner C, Stradrnann-Bellinghausen B. Complement reference typing report and nomenclature revision. Complement Inflamm.;  ;:  -  Schneider PM. Complement DNA RFLP reference typing report. Inflamm.;  ;:  - Mayer MM. Complement and complement fixation. In: Kabat EA, Mayer MM, eds. Experimental Immunochemistry. Springfield, IL: Thomas;  ;:  -