Genetic Examination of Children Suffering from Cystic Fibrosis

CFTR protein (cystic fi brosis trans membrane conductance regulator) is expressed in multiple epithelial tissues, including upper and lower respiratory tracts, pancreas, sweat glands and gastrointestinal tract. More than 800 mutations and 100 polymorphic variants of DNA sequences were identifi ed in patients with CF (Cystic fi brosis) and CFTRdiseases. In this study, genetic CFTR analysis of the children suff ering from chronic lung disease (cystic fi brosis) is presented. Th ey are treated and regularly controlled at the Pediatric hospital Sarajevo. CFTR analysis was done in 9 cases, 4 boys (44.4%) and 5 girls (55.55%). Th ere are 3 children (33.3%) in the age group 1 to 3 years, 1 child (11.1%) in the age group 3 to 6 years, 3 children (33.3%) in the age group 6 to 9 years and 2 children (22.2%) in the age group 9 to 12 years. Genetic analysis was conducted at the Medical center for molecular biology, School of Medicine, Ljubljana. PCR method with PAGE and direct sequestration on ABI PRISM 31 was applied. Th e majority of children (7 children, i.e. 77.77%) had CFTR mutation ∆ F 508 whilst one child had G542X mutation and one child R 1174 mutation. Th e purpose of this study is to emphasize the need for CFTR gene identifi cation in the institutes of our country.


Introduction
Cystic fibrosis (CF) is a complex gene syndrome revealed by dysfunction of all exocrine glands.It is defi ned by mutations of CFTR gene (cystic fi brosis trans membrane conductance regulator), which result in the production of hyper-viscous mucus and chloride malabsorbtion in the sweat glands' ducts (, , ).It is inherited as autosomal recessive trait, with gene locus for cystic fi brosis mapped at q.Th e most frequent mutation is ∆ F  that is found in approximately  of aff ected children.Th e mutation of CF gene is connected to deletion of three pairs of bases, which results in shift of phenylalanine residue to the position  of the mature protein (, ).Th e diagnosis of cystic fi brosis is established according to the criteria that can be divided into  groups ().Group A -clinical criteria: typical pulmonal clinical features, typical gastrointestinal clinical features and positive family history of cystic fi brosis in close relatives.Group B-laboratory criteria: Chloride concentration in the sweat and CFTR mutation.At least one criterion from each group is necessary for conclusive diagnosis.Th e treatment is symptomatic and supportive, until the introduction of gene therapy which means replacement of mutated CFTR gene with functional one.

Subjects and Methods
In this study we present the results of genetic analysis of  children, in the age between  and  years, who suff er from cystic fi brosis.Th ey are treated and monitored at the Pulmological department of the Pediatric Hospital Sarajevo.The diagnosis was established by repeated broncho-obstructions, X-ray examinations of the lungs, measurements of the enzyme activities in the duodenal secretions and measurement of chloride content in the sweat, which was above  mmol/l in all cases.Th e genetic analysis was realized using PCR based method, with PAGE and direct sequestration on ABI PRISM  Genetic Analyzer at the Medical center for molecular biology, School of Medicine, Ljubljana.

Results
In the Table . the results are presented for nine children,  girls and  boys - years of age, who suff er from cystic fi brosis.In  cases (.) ∆ F mutation of CFTR gene was identified.In the age group - years one GX mutation was identifi ed, while one R mutation was identifi ed in a girl from the age group - years.

Discussion
Cystic fibrosis is a chronic, multisystem disorder, most frequently characterized by pulmonal manifestations.Due to the modern supportive care, about half of the patients live to the age of  and about  of the patients survive until  years of age ().In our patients, the diagnosis of cystic fi brosis established based on clinical features and sweat test.Th e sweat test is the most important and standard diagnostic procedure ().

Conclusion
. Th e diagnosis of cystic fi brosis was confi rmed by genetic analysis, which is especially important in the case of atypical and mild forms of cystic fi brosis..In the future, cystic fi brosis will be cured when an adequate way of replacement of the defective CFTR gene with intact gene is found and an ideal vector for safe and effi cient entrance of CFTR gene into the cell is discovered.