Cystic fibrosis (CF) is an autosomal recessive genetic disorder caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), which is located at 7q31.2 and encodes 1480 amino acids. CFTR protein is responsible for regulating the transport of electrolytes and chloride across epithelial and mucus-producing cell membranes.

The discovery of the CFTR gene in the late 1980s triggered a surge of basic research that enhanced understanding of the pathophysiology and the genotype-phenotype relationships of this clinically variable disease of cystic fibrosis. More than 2000 variants of CFTR gene have been reported, and they are grouped to six classes depending on the pathophysiology of the CFTR protein ,The most common genetic defect reported in CF is the delta F508 mutation, Moreover, the degree of CF severity depends on the type of mutation, which typically affects the function and quantity of CFTR channels. When the CFTR protein is mutated, chloride ions accumulate in mucus-producing cells, resulting in a thick, sticky mucus that obstructs various pathways and hinders pulmonary, digestive, exocrine and male reproductive functions. Furthermore, mucus buildup increases a patient's susceptibility to airway obstruction, bacterial lung infection, pancreatic insufficiency, malabsorption and infertility. CF is characterized by significant clinical heterogeneity.

Inclusion Criteria:

• Children and adolescents aged 2 days - 18 year.
• patients clinically suspected or diagnosed with cystic fibrosis
• patients diagnosed with cystic fibrosis and attending or referred to the Pediatric pulmonology clinic at Sohag University Hospital.

Exclusion Criteria:

• Patient with cystic fibrosis like symptoms with another confirmed diagnosis ex. primary ciliary dyskinesia

Pediatric pulmonology clinic