Effect of the chromosome 1 locus on white blood cell counts.

*European ancestry at the locus has an essentially dominant effect on white blood cell counts. None of the differential counts phenotypes shows a significant difference between the 1,647 FY−/FY+ heterozygotes and 247 FY+/FY+ homozygotes after correcting for 7 hypotheses tested (Bonferroni corrected P = 0.48). However, all white blood cell counts except bands show significant associations comparing the 4,111 FY−/FY− homozygotes to the 1,894 carriers of the FY+ allele (Z-scores between 4.2 and 49.7 standard deviations).†After controlling for neutrophil level, there is weak additional evidence for association to the chromosome 1 locus only for monocytes and basophils. For subsequent mapping analyses we only focused on neutrophil levels, as adding these other residuals did not substantially increase the strength of the association. We do not estimate correlation coefficients of the associations that are not significant.