Table 2b. Frequency distributions of PTX3 gene single nucleotide polymorphisms (SNPs) in patients with (PA) and without (non-PA) PA colonization.

SNPs	Associated allele	Frequencies in PA patients (n=75)	Frequencies in non-PA patients (n=52)	χ2	P-value
rs2305619	A	0.573	0.413	6.281	0.012
rs1840680	A	0.567	0.413	5.767	0.016
rs3845978	C	0.980	0.962	0.781	0.377
rs35948036	C	0.020	0.010	0.467	0.513
rs3816527	C	0.507	0.375	4.297	0.038

Abbreviations: CF, cystic fibrosis; PTX3, pentraxin 3.

The Pseudomonas aeruginosa (PA) colonization was defined as the presence of PA in at least three consecutive sputum cultures collected in a 6-month period. To have an adequate clinical history, we have selected CF patients who were ⩾11 years old. Age at the time of first PA colonization is reported for each patient with bacterial colonization (75 patients: 39 females, 36 males; age range, 11–45 years), whereas chronological age at the time of the study is reported for patients without PA colonization (52 patients: 31 females, 21 males; age range, 11–52 years). The two groups of patients were comparable for age (CF with PA colonization 20.5±0.78 years versus CF without PA colonization 23.3±1.37 years) and for sociodemographic variables. The two groups of patients were followed up in the same time periods, thus undergoing similar protocols of eradications of PA. As a definition of chronic colonization, we adopted the most widely accepted, that is, presence of Pseudomonas in sputum, in three samples obtained in a period of 1 year. Chronic colonization was not reversible in our patients. On the other hand, patients not colonized by PA were consistently found Pseudomonas-free and did not undergo specific anti-Pseudomonas treatments in the attempt to eradicate the germ.

To correct for multiple testing, we performed 1000 permutations (HaploView 4.2).