Turkish Cystic Fibrosis Patients Research Articles

Beyond the 10%: Unraveling the genetic diversity in Turkish cystic fibrosis patients not eligible for CFTR modulators.

Cystic fibrosis (CF) is an autosomal recessive disease caused by variants of CFTR gene. Over 2000 variants have been identified, and new drugs called CFTR modulators have been developed to target specific defects in the CFTR protein. However, these drugs are only suitable for patients with certain variants of CFTR, and eligibility rates vary depending on race and geographical region. This study aimed to reveal the detailed genotype and clinical characteristics of people with CF (pwCF) at our center in Turkey, a developing country, who are not eligible for CFTR modulators. A total of 445 pwCF followed up at Marmara University were reviewed retrospectively. Variants of the patients ineligible to CFTR modulators were classified based on American College of Medical Genetics guidelines, CFTR classification, the change in the encoded protein, and the variant type. The study revealed that 139 (31.2%) patients weren't eligible for CFTR modulators. There were 60 different variants in the 276 alleles, as two were missing. The majority of patients had missense or nonsense variants, and that the most common variant was c.1545_1546del, which can be said unique to this geography. The study highlights the importance of detecting the variants of ineligible patients in detail to guide future approaches for more targeted and effective interventions in CF care. Testing the effectiveness of CFTR modulators for rare or newly occurring variants is crucial to ensure equal access for pwCF to these therapies from different racial backgrounds and ethnic minorities.

Evaluation of the health-related quality of life in Turkish cystic fibrosis patients.

Prolongation of life expectancy in cystic fibrosis (CF) to the fourth decade makes health-related quality of life (HRQOL) an important issue in this population. This study aims to evaluate the effects of clinical and socio-demographic characteristics of patients on different aspects of HRQOL in a pediatric CF population. We also intend to assess some measures of reliability and validity of the Turkish CF Questionnaire-Revised (CFQ-R) forms. Fifty-four CF patients and 46 parents / caregivers filled the appropriate CFQ-R forms. Disease severity was evaluated via modified Shwachman-Kulczycki (SK) scores, and additional clinical information was obtained from patient records. Forty-three percent (n=23) of patients were female, the mean age of patients being 13.3±3.96years. Self- and proxy-reported points showed a strong correlation (Spearman's rho>0.6) on more observable domains of HRQOL (e.g. physical functioning). No significant difference was found between sexes on any HRQOL domain. When compared between age groups, treatment burden appeared to worsen with age, while social functioning improved. All three forms of the CFQ-R Turkish version showed acceptable internal consistency reliability and convergence with disease severity measures. The CFQ-R showed a fair correlation with the Shwachman-Kulczycki score and the FEV1% value, which makes its longitudinal use possible in clinical practice. It is important to use self-reported evaluations as well as parent / caregiver-reported HRQOL evaluations, especially in young children. More studies are needed to assess the psychometric properties of Turkish CFQ-R forms.

Determination of Azole Resistance and TR34/L98H Mutations in Isolates of Aspergillus Section Fumigati from Turkish Cystic Fibrosis Patients.

Aspergillus fumigatus is the species section Fumigati most frequently isolated from the respiratory tract of cystic fibrosis (CF) patients. Recent studies suggest that mutations in the Cyp51 gene, particularly TR34/L98H, are responsible for azole resistance. The focus of this study was on section Fumigati isolates isolated from the respiratory tract samples of CF patients. More specifically, the goal was to detect A. fumigatus isolates, test their antifungal susceptibility to itraconazole, voriconazole and posaconazole, and finally determine the presence of TR34/L98H and other mutations in the isolates Cyp51A gene. A set of 31 isolates of Aspergillus section Fumigati were obtained from the sputum samples of 6 CF patients and subsequently identified to species level by microsatellite genotyping. All isolates were determined as A. fumigatus and involved 14 different genotypes. The minimal inhibitory concentrations to the three azoles were determined by the E-test method, and the Cyp51A gene was sequenced. One of the genotypes was found to be resistant to all azoles but no mutations were detected in the Cyp51A gene, especially the TR34/L98H mutation. Therefore, mutations in genes other than Cyp51A or other distinct mechanisms may be responsible for this reported multiazole resistance found in a Turkish CF patient.

Prevalence and drug resistance of mycobacteria in Turkish cystic fibrosis patients.

BackgroundIsolation of mycobacteria in cystic fibrosis (CF) patients is increasingly being reported. Because of having long term antimicrobial treatment, CF patients are at risk of pulmonary infection with especially resistant nontuberculous mycobacteria (NTM) strains. The aim of the present study is to determine the prevalence of mycobacterium spp. and antimicrobial susceptibility in Turkish CF patients.MethodsDuring a 5.5 year study period, 376 sputa from 130 CF patients were analyzed. Antimycobacterial susceptibility testing was performed by the Bactec 460 TB System and the E test method.ResultsTotaly 28 (7.44%) Mycobacterium spp. were isolated from eight (6.15%) CF patients. Five isolates (17.9%) were identified as Mycobacterium tuberculosis complex (MTBC), 14 (50%) as Mycobacterium abscessus and nine (32.1%) as Mycobacterium lentiflavum. All MTBC isolates were found to be susceptible to streptomycin, isoniazid, rifampicin, and ethambutol. Resistance to some antibiotics was detected in some NTM strains. These are the first data about the prevalence of mycobacteria in CF patients from Turkey.ConclusionsIn pediatric CF patients, specific mycobacterial analysis of sputum specimens and susceptibility testing should be performed for allowing early detection, identification and the possibility of eradication of these bacteria.

Frequency of fungi in respiratory samples from Turkish cystic fibrosis patients

An increased isolation of fungi from the respiratory tract of patients with cystic fibrosis (CF) has been reported. The prevalence of different fungi in CF patients from Turkey is not known. Our aim was to determine the frequency of fungi in the respiratory tract of Turkish CF patients. We investigated a total of 184 samples from 48 patients. Samples were inoculated on Medium B+ and CHROMagar Candida. Candida albicans was the predominant yeast isolated [30 patients (62.5%)], followed by C. parapsilosis [6 (12.5%)] and C. dubliniensis 5 (10.4%). Aspergillus fumigatus was the most common filamentous fungus [5 (10.4%)] and non-fumigatus Aspergillus species were isolated from four (8.3%) patients. Staphylococcus aureus was the most frequently detected bacterium in C. albicans positive samples (53.57%). A. fumigatus and Pseudomonas aeruginosa or S. aureus were detected together in 75% of A. fumigatus positive samples each. No statistically significant relationship was detected between growth of yeast and moulds and age, gender, the use of inhaled corticosteroids or tobramycin. No significant correlation was found between the isolation of C. albicans, A. fumigatus and P. aeruginosa, Stenotrophomonas maltophilia or S. aureus, and the isolation of C. albicans and Haemophilus influenzae. Other factors which may be responsible for the increased isolation of fungi in CF need to be investigated.

Nutritional status in Turkish cystic fibrosis patients

Nutritional status in Turkish cystic fibrosis patients

Highest heterogeneity for cystic fibrosis: 36 mutations account for 75% of all CF chromosomes in Turkish patients.

We analyzed the CFTR locus in 83 Turkish cystic fibrosis patients to identify mutations, haplotypes, and the carrier frequency in the population. We detected 36 different mutations in 125 (75%) of the total 166 CF chromosomes. Seven novel mutations were identified: four missense (K68E, Q493P, E608G, and V1147I), two splice-site (406 -3T > C and 3849 +5G > A), and one deletion (CFTRdele17b,18). The data showed that the Turkish population has the highest genetic heterogeneity at the CFTR locus reported so far. The results of this thorough molecular analysis at the CFTR locus of a population not of European descent shows that CF is not uncommon in all such populations. The large number of mutations present, as well as the high heterogeneity in haplotypes associated with the mutations suggests that most of the mutations have persisted for a long time in the population. Consistently, the carrier frequency is assessed to be high, indicating that the disease in the population is ancient.

Cystic fibrosis mutations and associated haplotypes in Turkish cystic fibrosis patients.

Identification of mutations causing cystic fibrosis (CF) in the Turkish population is essential for assessment of the molecular basis of CF in Turkey and the development of strategies for prenatal diagnosis and genetic counseling. Here, we present an updated report of mutations found in the Turkish CF population from an extensive screening study of the entire coding region, including exon-intron boundaries and the promoter region. Cases for which mutations could not be identified were also screened for previously defined large alterations and (TG)mTn-M470V loci. This study revealed a total of 27 different mutations accounting for almost 60% of disease genes in the Turkish population. In this study, we also identified the haplotypes associated with 17 mutations and those associated with unknown mutations. The mutation spectrum of CF in Turkey and its associated haplotypes indicated the presence of a major Mediterranean component in the contemporary Turkish population.

Analysis of the CFTR gene in Turkish cystic fibrosis patients: identification of three novel mutations (3172delAC, P1013L and M1028I).

In order to determine the spectrum of cystic fibrosis (CF) mutations in the Turkish population, a complete coding region of the cystic fibrosis transmembrane conductance regulator (CFTR) gene including exon-intron boundaries, on 122 unrelated CF chromosomes from 73 Turkish CF families was analysed by denaturing gradient gel electrophoresis and multiplex heteroduplex analysis on MDE gel matrix. In addition to 15 previously reported mutations and 12 polymorphisms, three novel mutations, namely 3172delAC, P1013L and M1028I, were detected. DeltaF508 was found to be present on 18.8% of CF chromosomes. The second most common mutation was 1677delTA, with a frequency of 7.3%, followed by G542X and 2183AA-->G mutations, with frequencies of 4.9%. These four most common mutations in Turkish CF population account for approximately 36% of mutations. This study could only detect 52.5% of disease-causing mutations in this population; 47.5% of CF alleles remain to be identified, reflecting the high molecular heterogeneity of the Turkish population.

Study of 12 mutations in Turkish cystic fibrosis patients.

67 unrelated cystic fibrosis (CF) patients were screened for some of the most common mutations of the CFTR gene. This analysis resulted in the identification of 34.6% of all CF alleles. The most common mutation is delta F508 (28.4%). Two other mutations account for a further 6.7% of the alleles (R347H: 3.0%; N1303K: 3.7%). 1677delTA, G542X, G551D, S549N/I, R553X, L558S, R334W, and R297Q were not detected.

Cystic fibrosis: the impact of analytical technology for genotype-phenotype studies

The generalized exocrinopathy cystic fibrosis (CF) is the most common severe genetic in Caucasian populations. A panel of more than 700 chromosomes from German and Turkish CF patients was screened for disease-causing mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene by c hemical cleavage of mismatch, single strand conformation polymorphism, restriction analysis and direct sequencing of genomic DNA amplified by polymerase chain reaction. Besides the major 3-bp deletion, ΔF508 that was found on 73% of German CF chromosomes, more than 50 other missense, nonsense, frame-shoft, and splicesite mutations have already been identified. In general, CFTR mutation is linked with a single 10-marker haplotype which indicates that in most cases a particular mutation spread from a common ancestor. The comparison of mutation genotypes with the disease phenotype emphasized the causative of the type and localization of the CFTR mutation for clinical course and prognosis. Pancreatic status and the risk of colonization of airways with opportunistic pathogens are genetically determined. Most patients who are harbouring mutations in the nucleotide binding folds were suffering from severe CF disease. Mild or even aberrant forms of CF went observed for many missense mutations located in the putative transmembrane domains or for mutations that are expected to result in a truncated protein of half of wild-type CFTR.

Frequency of the F508 deletion in the CFTR gene in Turkish cystic fibrosis patients

The F508 deletion in the cystic fibrosis transmembrane conductance regulator (CFTR) gene was found in 8 out of 30 Turkish cystic fibrosis (CF) chromosomes (27%). Five Turkish delta F508 CF chromosomes were associated with the risk haplotype B in KM19 (2 allele)/XV2c (1 allele). In the Turkish population, cystic fibrosis is predominantly caused by mutations other than the F508 deletion.