Frequency of Genotype With ΔF508 Mutation in CFTR Gene Among Iranian Cystic Fibrosis Patients With Pancreatic Insufficiency

Ahmad Khodadad; Elaheh Elahi; Setareh Sadat Bani Hassani; Pejman Rouhani; Bamdad Sadeghi; Nima Rezaei

doi:10.5812/ijp.3419

Frequency of Genotype With ΔF508 Mutation in CFTR Gene Among Iranian Cystic Fibrosis Patients With Pancreatic Insufficiency

Ahmad Khodadad ^{1
, 2
, *} , Elaheh Elahi ³ , Setareh Sadat Bani Hassani ¹ , Pejman Rouhani ¹ , Bamdad Sadeghi ⁴ and Nima Rezaei ^{4
, 5
, 6}

Authors Information

¹ Children’s Medical Center, Pediatric Center of Excellence, Tehran University of Medical Sciences, Tehran, IR Iran

² Department of Pediatrics, Tehran University of Medical Sciences, Tehran, IR Iran

³ School of Biology, College of Science, University of Tehran, Tehran, IR Iran

⁴ Research Center for Immunodeficiencies, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, IR Iran

⁵ Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, IR Iran

⁶ Universal Scientific Education and Research Network, Tehran, IR Iran

Article information

Iranian Journal of Pediatrics: December 28, 2015, 25 (6); e3419
Published Online: December 23, 2015
Article Type: Brief Report
Received: July 5, 2015
Accepted: August 22, 2015
DOI: 10.5812/ijp.3419

To Cite: Khodadad A, Elahi E, Bani Hassani S S, Rouhani P, Sadeghi B, et al. Frequency of Genotype With ΔF508 Mutation in CFTR Gene Among Iranian Cystic Fibrosis Patients With Pancreatic Insufficiency, Iran J Pediatr. 2015 ; 25(6):e3419. doi: 10.5812/ijp.3419.

Abstract

Copyright © 2015, Growth & Development Research Center.This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.

1. Background

2. Objectives

3. Patients and Methods

In this cross sectional study, 36 documented CF patients (17 males and 19 females), aged 2 to 42 months, with dominant phenotype of pancreas insufficiency (PI) who regularly attended Children's Medical Center in Tehran were investigated. The inclusion criteria for Pancreas Insufficiency (PI) were defined as two positive results of sweat test and history of steatorrhea confirmed by detecting fat drops in stool examinations. Demographic data, along with clinical, paraclinical and radiologic features which represent the spectrum of phenotypes were obtained by hospital documents and questionnaires designed for the study. Blood samples of 1-2 cc volumes were provided from each patient and DNA was extracted and examined for genetic assays to detect ΔF508 mutation of each allele of CFTR.

4. Results

Assessment of 36 patients with mutant primer showed that 9 were identified to have deletion mutations of ΔF508. Then, all samples were investigated for homozygosity with normal primer in which from all patients, 34 had one normal allele. 7 were heterozygotes, and 2 were homozygous for ΔF508 mutation. At last, from 72 studied alleles, 11 were found affected by ΔF508 mutation. Patients were classified into 3 groups by genotypes: homozygous for ΔF508 (5.5%), heterozygotes (19.4%) and non-mutated by ΔF508 (75%). In this study, all patients had FTT (Fail to Thrive) with a growth percentile curve of fewer than 3% or depletion of growth curve more than 2 curves in growth percentile chart. In patients with positive pharyngeal culture, organisms were as follow: Pseudomonas aeroginosa, streptococcus group A, Staphylococcus aurous, Klebsiella and Candida.

The frequency of various clinical presentations categorized by genotypes is shown for all patients (except in one with incomplete medical document) in Table 1. Dyspnea was one of the clinical symptoms with different correlations in different genotype. In homozygous patients for ΔF508 mutations compared with those not affected by ΔF508, dyspnea was significantly more prominent (P = 0.049). Frequency of bronchiectasis in homozygotes group was also significantly higher than in non-mutated subjects (P = 0.015), while this rate was significantly higher in heterozygotes in comparison with non-mutated group (P = 0.043). Quantitative comparison of sweat chloride concentration in homozygotes group with non-mutated group showed significant difference (P = 0.012), but this significance was not the same between homozygotes and heterozygotes group for ΔF508 mutation (P = 0.1), and between heterozygotes and non-mutated groups (P = 0.213). Fatty droplets in stool exam were significantly more numerous in homozygotes group for ΔF508 than others (P = 0.022), but there were no significant difference of droplets number between homozygotes and heterozygotes group, and heterozygotes with non-mutated ΔF508 (P = 0.088 and P = 0.516, respectively).

Table 1. Clinical Manifestations of All Patients and Respected to Δf508 Mutation Genotypes

Clinical Manifestations	Presence of signs/symptoms			Without Δ F508 Mutation			Heterozygous for Δ F508			Homozygote for Δ F508
Clinical Manifestations	Yes	No	Unknown	Present ^a	Absent ^a	Unknown	Present ^a	Absent ^a	Unknown	Present ^a	Absent ^a	Unknown
Cough	32	3	1	24 (92.3)	2 (7.7)	1	7 (100)	0	0	1 (50)	1 (50)	0
Dyspnea	15	20	1	8 (30.8)	18 (69.2)	1	5 (71.4)	2 (28.6)	0	2 (100)	0	0
Bronchitis	2	33	1	1 (3.8)	25 (96.2)	1	1 (14.3)	6 (85.7)		2 (100)	0	0
Bronchiectasia	4	31	1	1 (3.8)	25 (96.2)	1	2 (28.6)	5 (71.4)	0	1 (500)	1 (50)	0
Bronchiolitis	2	33	1	0	26 (100)	1	2 (28.6)	5 (71.4)	0	0	2 (100)	0
Pneumonia	22	13	1	14 (53.8)	12 (46.3)	1	7 (100)	0	0	1 (50)	1 (50)	0
Diarrhea	7	28	1	4 (15.4)	22 (84.6)	1	2 (28.6)	5 (71.4)	0	1 (50)	1 (50)	0
Edema	7	28	1	5 (19.2)	21 (80.8)	1	1 (14.3)	6 (85.7)	0	1 (50)	1 (50)	0
Anemia	10	12	14	9 (56.2)	7 (43.8)	11	1 (20)	4 (80)	2	0	1 (100)	1
Total Hyperbilirubinemia	3	28	5	2 (9.1)	20 (90.9)	5	0	7 (100)	0	1 (50)	1 (50)	0
Direct Hyperbilirubinemia	3	28	5	2 (9.1)	20 (90.9)	5	0	7 (100)	0	1 (50)	1 (50)	0
Salt kiss	11	5	20	10 (71.4)	4 (28.6)	13	1 (50)	1 (50)	5	0	0	2
Ascitis	1	29	6	1 (4.5)	21 (95.5)	5	0	6 (100)	1	0	2 (100)	0
Reflux	10	19	7	6 (30)	14 (70)	7	3 (42.9)	4 (57.1)	0	1 (50)	1 (50)	0
Hyperinflation in CXR	16	14	6	10 (47.6)	11 (52.4)	6	4 (42.9)	3 (57.1)	0	2 (100)	0	0
Vomiting	12	20	4	13 (53.5)	10 (43.5)	4	2 (28.6 )	5 (71.4)	0	0	2 (100)	0
Hypokalemia	13	19	4	11 (40.7)	12 (52.2)	4	5 (71.4)	2 (28.6 )	0	0	2 (100)	0
Hypernatremia	13	19	4	11 (47.8)	12 (52.2)	4	2 (28.6)	5 (71.4)	0	0	2 (100)	0
Metabolic alkalosis	14	18	4	12 (44.4)	11 (40.7)	4	2 (28.6)	5 (71.4)	0	0	2 (100)	0
Organomegaly	8	24	4	7 (30.4)	16 (69.6)	4	0	7 (100)	0	1 (50)	1 (50)	0

^aData are presented as No. (%).

5. Discussion

This study was conducted regarding the necessity of detecting genetic mechanisms interacting in pathogenesis of CF, and description of phenotypes in relation to underlying genotypes. Frequency of ΔF508 in our patients with PI was 11 (15.2%) from all 72 alleles studied. This value was comparable with data of previous reports on CF prevalence in Iran without considering special related phenotypes (7-9). In correlation of clinical phenotypes with the genotype groups, frequency of dyspnea in homozygotes for ΔF508 was documented significantly higher than in heterozygotes and non-mutated groups for ΔF508. Bronchiolitis was found more prevalent in heterozygote group than others; and bronchiectasis was also more significantly prevalent in heterozygous and homozygous patients for ΔF508 mutations compared with non-mutated ones. The results of our research in agreement with other studies clarifies that the more ΔF508 mutation affects alleles, the more respiratory complications are accompanied with genotype (10).

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