The diagnosis of CF in Iraq is challenging due to physicians’ low index of suspension. This disease was thought to be rare in this region and is similar in its presentation to other more common diseases in Iraq like tuberculosis, celiac disease, and immunodeficiency states. Lack of CF neonatal screening program and non-uniform availability of sweat chloride test or genotyping makes confirmation of clinical suspicions rely on clinical response to some available therapies like pancreatic enzyme supplementation, long-term course of the disease, and diagnosis by exclusion.
Interest in this disease has grown in the last decade as more patients are being discovered in Iraq, mostly in pediatric age groups. However, no published data or formal figures are available on the incidence and impact of CF in Iraq.
One unpublished study has been performed by Abbadi AF and Al-Janabi MK in 2016 that focused mainly on clinical characteristics and course of the disease of forty CF Iraqi children. A recently published study was conducted on 30 CF Iraqi children and analyzed exon 10 and exon 17a of CFTR gene using Sanger sequencing without clinical correlation. They found 2 mutations and one polymorphic variant in 17 CF patients, namely F508del in 5 (16.6%) patients, and S466X in 1 (3.3%) patient and M470V polymorphism in 11 (36.6%) patients ; F508del was the only one tested for in the current study.
In this cross-sectional study, we described the demographic data, presentation, investigations, and complications of the clinically confirmed patients with CF. The overall M:F ratio of both groups was 1.6:1, which is nearly similar to that found in Bahrain, Saudi Arabia, Jordan, and Egypt with a M:F ratio of 1.37, 1.33, 1.32, and 1.5 respectively . All patients enrolled in this study were children.
Parental consanguinity among 31 CF patients was 87.1%. This is higher than the average consanguinity rates among Iraqi general populations (40–49%)  but similar to the rates reported for other hereditary conditions in Iraq . This finding also helps to explain the increasing occurrence of rare conditions such as CF and familial aggregation of patients which is seen in 5 (16.13%) patients, similar to that reported in other regional countries [12, 13].
Almost all patients 30/31 (96.78%) presented during the first year reflecting disease severity. This was nearly similar to a study from Egypt where 86% of patients presented during the first year of life .
Mutational analysis of all tested patients in this study (n = 72) showed that 3120+1G>A and W1282X were the most frequently detected mutations as seen in 3 (4.17%) patients each. The former is known as the African CF mutation and has a frequency of 12.2% in African-American people  and was reported in an Iranian study with a similar frequency as ours . The other mutation, W1282X, was reported as the most common mutation in patients from Arab ethnic backgrounds  and has a similar frequency to an Egyptian study . This result was different from what was detected in a recently published Iraqi study which revealed that F508del mutation was the most commonly encountered mutation in a sample of 30 Iraqi CF patients as seen in 5 (16.6%) patients . This mutation was the second most common mutation detected in the current study along with R1162X with a frequency of 2.78% as detected in 2 patients each.
F508del is considered the most common CFTR mutation in other Arab countries like Lebanon (34%)  and Egypt (58%) , while R1162X has only been reported in Egypt in 3 patients (6%)  but was the second-ranking mutation in the previously published Iraqi study, where 5(16.6%) patients had this mutation . For these reasons, this mutation needs to be included in all future tests.
The other 4 mutations detected in this study were seen in one patient only with a frequency of 1.38% each and included (3272-26A>G, R347P, I507del, and 2183AA>G).
3272-26A>G mutation, which creates an alternative acceptor splice site in intron 17a, is considered the second most common mutation after F508del in the Belgian CF population with a frequency of 3.8% . Al-Abadi et al study showed this mutation in one Jordanian patient .
Searching published reports from the Arab world showed that R347P mutation was only reported in Egypt in 2% of patients  along with the current study. The worldwide frequency of R347P mutation is about 0.2% and it is mostly found in the south of Bulgaria .
I507del mutation is only reported in this study but not in other regional countries, while 2183AA>G was detected in Jordan (6%) , Iran (7%) , Turkey (2.5–4.9%) , and the Northeast of Italy (9.3%) .
All patients with detected mutations from the first group (n = 5) presented during the first year which is the usual age of presentation of CF patients ; all had abnormally high levels of sweat chloride values and failure to thrive which may necessitate aggressive management to slow the progress and reduce potential complications. One patient in this study had R1162X mutation and presented with milder pulmonary manifestations. This mutation results in a protein with a residual regulatory region that may be partially functioning in the lung tissues .
Over the years, the IVS8 c.1210-12T[5_9] (polypyrimidine tract in intron 8) and adjacent c.1210-35_1210-12GT[8_13] (TG repeat tracts) in the CFTR gene have received much more attention due to their potential roles in the development of male infertility. The polymorphic IVS8 c.1210-12T[5_9] consists of three common variants, namely 5T, 7T, and 9T, and this locus functions as the acceptor site of alternative splicing of CFTR exon 9 .
The presence of some polymorphic variants is not by itself pathogenic, but some variants are associated with the presence of certain splice mutations. The shortest (5T) is associated with the highest rate of incomplete transcripts. mRNA without exon 9 results in immature CFTR proteins with improper function .
The 7T allele can be found in normal individuals with a relative frequency of 80% in Caucasians  and 90% in East Asians . In the current study, IVS8 7T/7T variant was detected in 50% of patients which was nearly similar to what was reported in a study from Iran (60%); IVS8 7T/9T and 5T/7T heterozygous states were detected in 16.7% in this study but in 30% in the same study from Iran ; the same applies to 9T/9T variant, which was detected in 6.94% in the current study but more in the Iranian study (10%) . This particular variant was also encountered in association with F508del mutation in two patients, unlike the Lebanese study that showed 66.7% of the F508del was associated with 7T allele .
Some mutations detected in this study were not associated with any of the tested c.1210-12T[5T/7T/9T] variants in the used kit. The presence of mutations without a detected variant is expected as other variants have not been tested, which may suggest that some specific Iraqi combinations may exist and be associated with novel pathogenic variants in the same allele.
Differences in allele frequencies and clinical presentation could be related to the considerable heterogeneity in CFTR mutations, a variation of these mutations in different populations, in addition to the interaction of genetic and environmental factors .
All detected mutations have a high genotype/phenotype correlation as all patients express typical and moderate-severe clinical presentation and disease course.
Based on these findings, the currently used kit can diagnose about 20% of patients; the remaining 80% require further testing for large rearrangements with quantitative methods. Such methods could include multiplex ligation-dependent probe amplification (MLPA) or next-generation sequencing (NGS) with an adapted algorithm and specific sequencing of well-known deep intronic variants. These tests could be the next step to complete the CFTR gene analysis of molecularly undiagnosed patients. They may reveal probable novel mutations as Iraq, especially the central parts, is well known to harbor heterogeneous mutations from all over the world  as it was once the center of attention in education and trade.