Analysis Variants of the CFTR Gene in Iranian Cystic Fibrosis Patients

Abstract

Background: Cystic fibrosis (CF) is known as one of the most common autosomal recessive disorders, which is caused by mucosal glands. A deficiency in the Cystic fibrosis transmembrane conductance regulator gene (CFTR), which encodes a chloride channel, triggers damage to epithelial cells in respiratory ducts, pancreas, intestine, genital ducts in males, liver system, and sweat glands. Objective: This study aimed to conduct the sequencing of 27 exons of the CFTR gene to screen the spectrum of the variants in patients from all over Iran from different ethnicities. Methods: This study is a descriptive-analytical, that was performed for eleven years from 2010 to 2021. Totally 345 patients were referred to Tehran Medical Genetics Laboratory by specialists. These patients were categorized into four groups. The first group included clinically confirmed patients of CF having clinical features and biochemical abnormalities, plus a positive sweat chloride test. The second group included couples with an alive or deceased child affected. The third group included CBAVD (Congenital bilateral absence of the vas deferens) cases, and the fourth group included prenatal diagnoses who were looking for carrier detection, or her spouse is affected with CBAVD. Results: Fifty-four variants and five deletions were found from 345 patients, the most common frequent variant were c.1521_1523delCTT ([delta]F508) (47 (6.81%)), c.1000C>T (R334W, 31 (4.45%)), c.1911delG (2043delG, 25 (3.62%)), c.2051_2052delAAinsG (2183AA->G, 15 (2.17%)), c.1624G>T (G542X, 12 (1.74%)), c.1697C>A (A566D, 12 (1.74%)), c.1210-12T [5] (9(1.30%)) and c.3196C>T (R1066C,7 (1.01%)) respectively and frequency of other variants were less than 1%. Deletion in some exons was established by MLPA assay, the most common deletion was c. (53+1_54-1) _ (164+1_165-1) del (CFTRdele2, 7 (1.01%)). Conclusions: This study improves our knowledge concerning carrier analysis and genetic counseling. Also, it helps to develop a cost-effective newborn screening program.