IFRD1 gene polymorphisms are associated with nasal polyposis in cystic fibrosis patients.

BACKGROUND: Nasal polyposis (NP) is an inflammatory disease of the upper nasal airways frequently present in CF patients. Interferon-Related Developmental Regulator 1 (IFRD1) gene was reported as a possible modifier of CF lung disease severity. Three IFRD1 SNPs were analyzed to investigate a possible effect on the development of NP in CF patients. METHODS AND PATIENTS: The DNA of 143 patients with CF (40 with and 103 without NP) was purified from peripheral blood samples. IFRD1 SNPs (rs7817, rs3807213, rs6968084) were genotyped by restriction enzyme analysis. RESULTS: The T allele of the common polymorphisms rs7817 and the rs7817-rs3807213 haplotype were associated with NP (p = 0.002 and 0.004, respectively). CONCLUSIONS: These results showed the association of the IFRD1-rs7817 polymorphism with NP in CF patients.

Predictive genetic testing -- new possibilities in determination of risk of complex diseases.

Predictive genetic testing offers the possibility to statistically determine the risk of inheriting a complex phenotype by establishing an individual s genotype for metabolic polymorphisms. Here we discuss the conditions under which a predictive test may be offered to a patient and the problems connected with it. Examples of predictive genetic testing for multifactorial diseases and drug responses are given. We describe in detail the association of the C677T polymorphism of methylentetrahydrofolate reductase gene with hyperhomocystinemia and folate levels, as an independent risk factor for cardiovascular disease, and the association of a polymorphism of the promoter of the 5-lipoxygenase gene and the response to leukotriene inhibitors in asthma. Prospective development of genomic medicine and its use in the study of complex traits will hopefully bring significant benefit to the population and enhance the prevention and therapy of common diseases.

Increased frequency of CFTR gene mutations in sarcoidosis: a case/control association study.

A complete screening of the CFTR gene by DGGE and DNA sequencing was performed in patients with sarcoidosis. In 8/26 cases, missense and splicing CFTR gene mutations were found, a significant difference over controls (9/89) from the same population (P = 0.014). The odds ratio for a person with a CFTR gene mutation to develop the disease is 3.95 (1.18 < OR < 13.26). Seven different CFTR gene mutations were observed: R75Q, R347P, 621 + 3 A/G, 1898 + 3 A/G, L997F, G1069R, and a novel mutation which was detected in this study, I991V. R75Q mutation was present in 3/26 patients, a significant increase (P = 0. 01) in cases over controls, indicating its preferential association with sarcoidosis. A trend towards disease progression was observed in patients with CFTR gene mutations compared to patients without mutations. These data suggest that CFTR gene mutations predispose to the development of sarcoidosis.

A new approach for identifying non-pathogenic mutations. An analysis of the cystic fibrosis transmembrane regulator gene in normal individuals.

Given q as the global frequency of the alleles causing a disease, any allele with a frequency higher than q minus the cumulative frequency of the previously known disease-causing mutations (threshold) cannot be the cause of that disease. This principle was applied to the analysis of cystic fibrosis transmembrane conductance regulator (CFTR) mutations in order to decide whether they are the cause of cystic fibrosis. A total of 191 DNA samples from random individuals from Italy, France, and Spain were investigated by DGGE (denaturing gradient gel electrophoresis) analysis of all the coding and proximal non-coding regions of the gene. The mutations detected by DGGE were identified by sequencing. The sample size was sufficient to select essentially all mutations with a frequency of at least 0.01. A total of 46 mutations was detected, 20 of which were missense mutations. Four new mutations were identified: 1341+28 C/T, 2082 C/T, L1096R, and I11131V. Thirteen mutations (125 G/C, 875+40 A/G, TTGAn, IVS8-6 5T, IVS8-6 9T, 1525-61 A/G, M470V, 2694 T/G, 3061-65 C/A, 4002 A/G, 4521 G/A, IVS8 TG10, IVS8 TG12) were classified as non-CF-causing alleles on the basis of their frequency. The remaining mutations have a cumulative frequency far exceeding q; therefore, most of them cannot be CF-causing mutations. This is the first random survey capable of detecting all the polymorphisms of the coding sequence of a gene.

Complete mutational screening of the CFTR gene in 120 patients with pulmonary disease.

In order to determine the possible role of the cystic fibrosis transmembrane regulator (CFTR) gene in pulmonary diseases not due to cystic fibrosis, a complete screening of the CFTR gene was performed in 120 Italian patients with disseminated bronchiectasis of unknown cause (DBE), chronic bronchitis (CB), pulmonary emphysema (E), lung cancer (LC), sarcoidosis (S) and other forms of pulmonary disease. The 27 exons of the CFTR gene and their intronic flanking regions were analyzed by denaturing gradient gel electrophoresis and automatic sequencing. Mutations were detected in 11/23 DBE (P = 0.009), 7/25 E, 5/27 CB, 5/26 LC, 5/8 S (P = 0.013), 1/4 tuberculosis, and 1/5 pneumonia patients, and in 5/33 controls. Moreover, the IVS8-5T allele was detected in 6/25 E patients (P = 0.038). Four new mutations were identified: D651N, 2377C/T, E826K, and P1072L. These results confirm the involvement of the CFTR gene in disseminated bronchiectasis of unknown origin, and suggest a possible role for CFTR gene mutations in sarcoidosis, and for the 5T allele in pulmonary emphysema.