Figure. Distribution of soluble CD14 according to ethnicity and sex. Median and interquartile ranges are indicated by the band and box edges, respectively. The whiskers indicate upper

rank correlation coefficient between sCD14 and CRP, fibrin- ogen, and IL-6 were 0.22, 0.21, and 0.17, respectively (all P<0.001). In age, race, and sex-adjusted models, sCD14 was positively correlated with baseline smoking, diabetes mellitus, fasting glucose, hypertension, and negatively correlated with BMI (all P<0.001; Table 1). The differences in sCD14 by race and sex persisted on adjustment for CVD risk factors (Table 1). When adjusted for baseline CHD and CVD risk factors, sCD14 was strongly and independently associated with other inflammatory and acute phase proteins, including CRP, IL-6, and fibrinogen, as well as with increased internal carotid artery wall thickness and decreased ABI (all P<0.001).

Complex Trait Analysis method using all genotyped autosomal SNPs. The estimate of sCD14 phenotypic variance explained by genomewide SNPs was 33±17% (P=0.03).

Genomewide Association Scan of sCD14 in EA and Blacks

In the genomewide association scan of 2952 EA and 528 blacks, 2 regions, 1q24 and 5q31, reached genomewide signif- icance in EA (Figure I in the online-only Data Supplement); the chromosome 5q31 peak was also genomewide significant in blacks (Figure II in the online-only Data Supplement). Results for the lead (index) SNPs associated with sCD14 in each genomic region are summarized in Table 2. In EA, the strongest genomewide association signal was located on chro- mosome 5q31, centered around the CD14 structural gene. The 5q31 region of association spanned ≈500 kb, encompassed 16 additional genes, and included an extended block of linkage disequilibrium containing 165 SNPs with P<5×10–8 (Figure IIIA in the online-only Data Supplement). The minor allele at the EA index SNP rs5744441 (minor allele frequency=0.22; imputation quality score=0.99) was associated with 101±10 ng/mL lower sCD14 (P=3.0×10–23). The rs5744441 SNP is located ≈3 kb upstream of CD14.

Estimation of Proportion of sCD14 Phenotypic Variation Explained by Genomewide SNPs

To our knowledge, family-based estimates of sCD14 heritability have not been previously reported. Therefore, we estimated the amount of phenotypic variance of sCD14 explained by distant genetic relationships between individuals with the CHS EA population by applying the Genome-wide

Table 1. Association Between Soluble CD14 and Other Cardiovascular Risk Factors and Measures of Subclinical Cardiovascular Disease at the CHS Baseline Examination

In the EA genome-wide association study (GWAS), a sec- ond region on chromosome 1q24.3 achieved genomewide significance (Table 2 and Figure IV in the online-only Data Supplement). The index SNP rs1063412 at 1q24.3 is a C/T polymorphism that encodes a Pro266Ser amino acid substitu- tion within the second exon of PIGC (MAF=0.43). According to the HapMap, the C allele (Pro266) is the minor allele in European and Asian populations, but is the major allele in African populations. The C allele (MAF=0.43 in CHS EA) was associated with 48±8 ng/mL lower sCD14 (P=1.4×10–8).

Model A Model B Model C Baseline Characteristic β±SE β±SE β±SE Age, y 7.13±0.86* 6.60±0.88* 4.34±0.90* Female sex 119±9.7* 123±9.6* 118±10.3* Black race −155±13.3* −164±13.5* −185±13.3* Current smoking 96±15* 84±15* 41±15** Diabetes mellitus 59±10* 66±11* 35±11** Hypertension 74±10* 78±10* 54±10* Systolic blood pressure, mm Hg 0.49±0.22 0.26±0.22 0.18±0.22 LDL cholesterol, mg/dL 0.34±0.12 0.44±0.13** 0.43±0.13** HDL cholesterol, mg/dL −1.02±0.32** −0.96±0.34** 0.38±0.34 Triglycerides, mg/dL 17.1±11.1 4.62±11.54 −30±13.4 Glucose, mg/dL 1.07±0.13* 1.00±0.16* 0.73±0.16* Insulin, mg/dL 0.84±0.18* 0.70±0.18* 0.40±0.18 BMI, kg/m2 −4.87±1.03* −4.87±1.03* −13.0±1.12* Waist circumference, cm −1.14±0.38** 0.316±0.674 −1.15±0.658 C-reactive protein, g/L 95±4.5* 101±4.7* 62±6.0* Interleukin-6, pg/dL 117±7.8* 117±8.1* 51±9.3* Fibrinogen, mg/dL 1.28±0.069* 1.26±0.070* 0.55±0.085* Internal carotid wall thickness, 75.6±8.80* 55.6±8.98* 36.7±8.96* mm

tion at the CD14 locus, but the specific SNPs associated with sCD14 were distinct from those in EA (Table 2 and Figure IIIB in the online-only Data Supplement). The index SNP in blacks rs778584 (MAF=0.31) was located in the 3´ flanking region and was associated with 128 ng/mL±24 higher sCD14 (P=5.5×10–9). The EA index SNP at the CD14 locus rs5744441 was less common (MAF=0.08) in blacks and associated more weakly with sCD14 (β=−108±38 ng/mL; P=0.003). In blacks, the PIGC rs1063412 C allele (Pro266) was considerably more common (MAF=0.83) than in EA. Nonetheless, the PIGC rs1063412 Pro266 variant was not significantly associated with sCD14 in blacks (P=0.95; Figure V in the online-only Data Supplement).

Haplotype Analysis and Fine-Mapping of CD14 Gene Region

LDL indicates low-density lipoprotein; HDL, high-density lipoprotein; CHS, Cardiovascular Health; and BMI, body mass index.

To further explore the CD14 gene variants associated with sCD14 in EA and blacks, we used denser CD14 genotype data from the IBC array, which contains 15 SNPs covering the CD14 coding, intronic, untranslated, and flanking regions. In EA, the most strongly associated SNP on the IBC array was rs5744455 (β=−101±9.5 ng/mL; P=3.5×10–26), located ≈50 bp upstream of the transcription start site. On the basis of 1000 Genomes Centre d’Etude du Polymorphisme Humain (CEU) data, this SNP is in strong LD with the index GWAS SNP,