Effect of NKG2C genotype on NK cell maturation phenotype and HCMV antibody titer. (A) Frequency of CD94⁺ cells within the CD56^dim NK cell population in individuals with zero (NKG2C^−/−), 1 (NKG2C^+/−), or 2 (NKG2C^+/+) copies of the NKG2C gene. (B) Effect of NKG2C genotype on the frequencies of CD94⁺ NK cells expressing either NKG2A⁺(NKG2C⁻) or NKG2C⁺(NKG2A⁻) cells. (C) Effect of NKG2C genotype on the frequency of CD57⁻, CD57^int, and CD57⁺ NK cells in subjects younger than 10 and 10 or more years of age. (D) Anti-HCMV antibody titers by age (years) and NKG2C⁻genotype. Horizontal bars represent median values, boxes extend from the 25th to the 75th percentile, and whiskers represent the 95th percentiles. Asterisks denote statistically significant differences between genotypes for all comparisons shown (*P < .05, ***P < .001, analysis of variance).