Polymorphisms in the Surfactant Protein A Gene Are Associated with the Susceptibility to Recurrent Urinary Tract Infection in Chinese Women

Abstract

Some risk factors for susceptibility to recurrent urinary tract infection (r-UTI) are well known, but the genetic role in acquiring the disease is poorly understood. Surfactant protein A and D (SP-A and SP-D) play an important role in modulation of lung inflammatory processes. The SP-A1 and SP-A2 genes encoding SP-A and the SP-D gene are highly polymorphic, and some of polymorphisms are associated with several infective diseases, including pyelonephritis. In the present study, we investigated whether some of these polymorphisms are associated with the risk of r-UTI in Chinese population. Genomic DNA was extracted from blood samples of 32 female patients with r-UTI and 30 age-matched, unrelated healthy female subjects. Genotyping of gene polymorphisms was analyzed by PCR. Among 11 single nucleotide polymorphisms (SNPs) (five of SP-A1, four of SP-A2 and two of SP-D) observed in the enrolled subjects, Ala19Val of SP-A1 and Lys223Gln of SP-A2 were associated with susceptibility to r-UTI. The frequencies of 19Ala allele of SP-A1 gene (p = 0.038) and 223Gln allele of SP-A2 gene (p = 0.012) in the patients were significantly higher than those in healthy subjects. The serum SP-A and SP-D levels were increased and the urine SP-A and SP-D levels were decreased in r-UTI patients compared with control subjects (p < 0.05). r-UTI patients with 19Ala/Ala or 223Gln/Gln genotype were associated with high serum and low urine SP-A levels (p < 0.01). Therefore, the 19Ala allele of SP-A1 gene and the 223Gln allele of SP-A2 gene are risk factors for r-UTI.