Original Article

Association of IL4 rs2070874, FoxP3 rs3761548
Polymorphisms with Keratoconus in Algeria

Wafaa Meteoukki1,2, MS; Mostefa Fodil2,3, PhD; Nawel Adda Negaz2,4, MD; Nesrine Rahmoun1, PhD
Sarah Lardjam Hetraf1, PhD; Hadjira Ouhaibi Djellouli1, PhD; Ahlem Djelti Messal1, PhD; Meriem Abdi1, PhD

Meriem Samia Aberkane1, PhD; Abdelillah Chiali4, MD; Amine Derdour5, MD; Aicha Idder2,5, MD
Faouzia Zemani-Fodil1,2, PhD

1Laboratoire de Génétique Moléculaire et Cellulaire (LGMC), Université des Sciences et de la Technologie d’Oran Mohamed
BOUDIAF- USTO-MB, BP 1505, El M’naouer, 31000 Oran, Algérie

2Agence Thématique de Recherche en Sciences de la Santé (ATRSS)– Oran, Algérie
3Ecole Supérieure des Sciences Biologiques d’Oran (ESSBO)

4Clinique Chiali, Oran, Algérie
5Laboratoire de Génétique Médicale Appliquée à l’Ophtalmologie, Clinique Hammou Boutlélis Oran, Algérie

ORCID:
Wafaa Meteoukki: https://orcid.org/0000-0001-9821-5808

Abstract

Purpose: The aim of this case–control study was to determine the impact of
environmental factors on the predisposition to develop keratoconus in a sample of
Western Algerian population. Subsequently, we were interested in the implication of
two single nucleotide polymorphisms (SNPs) IL4 rs2070874 and FOXP3 rs3761548,
previously described as contributing to the occurrence of allergy, in the development
of keratoconus.
Methods: The study included 70 unrelated KC cases and 70 controls originating from
Western Algeria. DNA genotyping was done using predesigned probe-based allelic
discrimination TaqMan® assays. Allele and genotype frequencies were compared
between the cases and controls by Chi-square test and odds ratios with 95%
confidence intervals.
Results: A significant association between risk factors such as family history, atopy,
eye rubbing, and the development of keratoconus was found in our sample. Smoking
would provide a protective effect against the pathology. No statistically significant
differences were found in the allele and genotype frequencies between cases and
controls neither for IL4 rs2070874 nor for FOXP3 rs3761548.
Conclusion: Our study provides, for the first time, a clear demonstration of the
absence of association of the allergy-associated IL4 and FOXP3 polymorphisms with
KC in a sample from Western Algerian population.

Keywords: Case–Control Study; FOXP3 Gene; IL4 Gene; Keratoconus; Polymorphisms;
Western Algeria

J Ophthalmic Vis Res 2021; 16 (4): 558–565

558 © 2021 METEOUKKI ET AL. THIS IS AN OPEN ACCESS ARTICLE DISTRIBUTED UNDER THE CREATIVE COMMONS ATTRIBUTION LICENSE | PUBLISHED BY KNOWLEDGE E

http://crossmark.crossref.org/dialog/?doi=10.18502/jovr.v16i4.9745&domain=pdf&date_stamp=2019-07-17


Keratoconus Associated Genes in Algeria; Meteoukki et al

INTRODUCTION

Keratoconus (KC) is a degenerative bilateral
corneal dystrophy characterized by gradual
thinning of the cornea leading to a loss of visual
acuity. KC is classified as a noninflammatory
disease;[1] however, several studies rejected this
theory after the discovery of the expression of
inflammatory mediators such as cytokines in the
tears of patients suffering from KC.[2, 3]

KC is a multifactorial disease resulting from
the interaction of environmental and genetic
factors. Although the etiology of KC is not clearly
established, genetic and environmental factors
such as allergy or eye rubbing seem necessary
for disease expression,[4] despite the positive
associations found between atopy (allergy, asthma,
eczema) and KC.[5–7] No study has focused on
the association between KC and polymorphisms
in inflammatory mediators genes of these immune
disorders.

Interleukin 4 is a pleiotropic cytokine produced
by activated T-lymphocyte and mast cells.[8] This
cytokine plays a major role in type 2 immune
responses characterized by the production of
immunoglobulin E (IgE) and immunoglobulin G1
(IgG1).[9] IgE is strongly implicated in atopic and
allergic diseases.[10] Several genetic variants in
the IL4 gene and its receptor IL4-R have been
found associated with allergic rhinitis (AR).[11] The
IL4 rs2070874 has been reported as associated
with asthma and atopy in several studies.[12, 13] Hai-
Jun Yang performed a meta-analysis and found
that this polymorphism is correlated with increased
asthmatic risk.[14]

The Forkhead box transcription factor (FOXP3)
has an important role in the development and
function of regulatory T cells (Tregs), and
also in peripheral tolerance.[15] Many severe
lymphoproliferative diseases occur due to Treg

Correspondence to:

Wafaa Meteoukki, MS. Laboratoire de Génétique
Moléculaire et Cellulaire, Université des Sciences et de
la Technologie d’Oran Mohamed BOUDIAF- USTO-MB,
BP 1505, El M’naouer, 31000 Oran, Algérie.
Email: wafaa.meteoukki@univ-usto.dz
Received: 23-11-2020 Accepted: 15-04-2021

Access this article online

Website: https://knepublishing.com/index.php/JOVR

DOI: 10.18502/jovr.v16i4.9745

deficiencies resulting from FOXP3 mutation. Thus,
Tregs mediate dominant tolerance to self and
have also been shown to be equally important
in the control of autoimmune diseases, allergy,
fetal–maternal tolerance, allograft tolerance,
and immunopathology.[16] The rs3761548
polymorphism of FOXP3 gene was identified
as being associated with AR in heterozygous form
in Han Chinese patients,[17] and in Hungarian AR
patients.[18]

To the best of our knowledge, this is the first
study dedicated to the study of KC in Algeria
and Africa in order to find a possible association
between the inflammatory gene polymorphisms
(rs2070874 and rs3761548) and the disease
pathology.

METHODS

Subjects

In total, 70 KC cases and 70 healthy controls
originating from Western Algeria were included
in this study. Patients were recruited from the
specialized hospital, Institute of Ophthalmology
EHS (établissemnt hospitalier specialisé) Hammou
Boutelilis in Oran Algeria as well as from a private
ophthalmology clinic. The control group included
voluntary donors from the blood transfusion
center of Oran hospital “CHUO” (Centre Hospitalo-
Universitaire d’Oran), as well as student volunteers
[Table 1].

The present study was conducted according
to the principles set out in the Declaration of
Helsinki,[19] and was approved by the ethics
committee at the National Evaluation and Planning
Committee of the Algerian University Research. An
informed written consent was obtained from all
participants.

Detection of KC was performed by an
experienced ophthalmologist based on visual
acuity assessment, findings of slit lamp as: corneal

This is an open access journal, and articles are distributed under the terms of
the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which
allows others to remix, tweak, and build upon the work non-commercially, as
long as appropriate credit is given and the new creations are licensed under the
identical terms.

How to cite this article: Meteoukki W, Fodil M, Negaz NA, Rahmoun
N, Hetraf SL, Djellouli HO, Messal AD, Abdi M, Aberkane MS, Chiali A,
Derdour A, Idder A, Zemani-Fodil F. Association of IL4 rs2070874, FoxP3
rs3761548 Polymorphisms with Keratoconus in Algeria. J Ophthalmic Vis
Res 2021;16:558–565.

JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021 559

https://knepublishing.com/index.php/JOVR


Keratoconus Associated Genes in Algeria; Meteoukki et al

Table 1. Study population’s characteristics

Characteristics KC cases (%) Healthy controls (%) P-value

Number of subjects 70 70 –

Men 21 (30%) 40 (57%) 0.001

Women 49 (70%) 30 (43%)

Age (mean ± SE), years 30.40 ± 11.33 30.14 ± 9.29 0.396
Family history of KC 15 (21%) 2 (3%) 0.0007

Consanguinity 21 (30%) 15 (21%) 0.24

Atopy 48 (69%) 11 (16%) 1×10−6

Eye rubbing 56 (80%) 1 (1%) 1×10−6

UV exposure 40 (57%) 50 (71%) 0.077

Exposure to cigarette smoke 27 (39%) 59 (84%) 1×10−6

KC, keratoconus; P, significance
The values are presented as the mean ± standard error; the P-value for each comparison is calculated and is timed significant if
it is superior than 0.05.

Table 2. Details of the SNP used in the study

Gene db SNP ID Assay ID Location Gene/Function

IL4 rs2070874 C__16176215_10 Chr.5: 132674018 5 Prime untranslated variant
FOXP3 rs3761548 C__27476877_10 Chr.X: 49261784 Intron variant

SNP, single nucleotide polymorphism; db SNP, single nucleotide polymorphism database; Chr, chromosome

Table 3. Genotypes and alleles distribution of IL4 rs2070874 and FOXP3 rs3761548 variants between keratoconus patients
and control group

Gene/SNP Genotype/Allele KC Patients n = 70 (%) Controls n = 70 (%) X² P-value OR [CI]

IL4 rs2070874 TT
CC
TC

6 (9)
43 (61)
21 (30)

3 (4)
49 (70)
18 (26)

1.62 0.44 _

T
C

33 (24)
107 (76)

24 (17)
116 (83)

1.78 0.18 0.67 [0.37–1.21]

TT+TC
CC

27 (39)
43 (61)

21 (30)
49 (70)

1.14 0.28 1.45 [0.72–2.91]

Gene/SNP Genotype/Allele KC Patients n = 70 (%) Controls n = 70 (%) X² P-value OR [CI]

FOXP3 rs3761548 TT
GG
GT

12 (17)
32 (46)
26 (37)

12 (17)
33 (47)
25 (36)

0.03 0.98 _

T
G

50 (36)
90 (64)

49 (35)
91 (65)

0.02 0.900 1.03 [0.63–1.68]

TT + GT
GG

38 (54)
32 (46)

37 (53)
33 (47)

0.03 0.86 1.06 [0.55–2.05]

KC, keratoconus; P, significance; OR, odds ratio; CI, 95% confidence interval

560 JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021



Keratoconus Associated Genes in Algeria; Meteoukki et al

thinning, Vogt’s striae,[20] and Fleischer’s ring and
topographic data. Patients previously grafted for
one or both eyes were considered as cases.

All KC patients with AR reported having common
classical symptoms mentioned in Allergic Rhinitis
and its Impact on Asthma (ARIA) guidelines-2016
revision,[21] as nasal itching, sneezing, rhinorrhea,
and nasal congestion, and other KC patients stated
that they already suffered from ocular symptoms as
allergic rhinoconjunctivitis associated with itching
and redness of the eyes and tearing.

The 70 control subjects had no ocular disease
or previous eye surgeries and no family ocular
history; all controls wearing glasses or suffering
from myopia were excluded.

DNA Extraction

Eight mL peripheral blood was collected from
patients and healthy controls using EDTA
containing tubes and stored at –20°C until
analyses. Genomic DNA was extracted using
the salting out method.[22]

Genotyping of IL4 rs2070874 and FOXP3
rs3761548 Polymorphisms

Molecular genotyping of SNPs was performed
using TaqMan® SNP genotyping assay (Applied
Biosystems Foster City, CA, USA) [Table 2] on
qTOWER³ real-time polymerase chain reaction
(PCR) machine (Analytik Jena, Germany). A 20 µL
PCR reaction contained 1X TaqMan® genotyping
master mix (Applied Biosystems Foster City, CA,
USA), 1X SNP genotyping assay mix, and 20
ng DNA. PCR cycling parameters included pre-
denaturation at 60°C for 30 sec, denaturation
at 95°C for 10 sec, followed by 50 cycles of
denaturation at 95°C for 15 sec each, and finally
annealing/extension at 60°C for 90 sec. The PCR
products were measured at 60°C for 30 sec, which
are proportional to the level of the fluorescence
VIC® and FAM®.

Statistical Analysis

The Hardy–Weinberg equilibrium (HWE) in the
control group was calculated using Chi-square test.
The comparison of quantitative variants between
KC patients and control group, the frequencies
of the allele and genotype were analyzed using

the Pearson’s Chi-square (χ2) test. P-values < 0.05
were considered significant. Risk was assessed by
the odds ratios (ORs) and 95% confidence intervals
(CIs) were also estimated.

The genotype relative risk (GRR) method (a
single genotype versus the others) was calculated
to compare the genotype distribution in patients
and controls. All the analyses were done using 2×2
contingency tables.

RESULTS

The demographic and other characteristics of all
subjects are shown in Table 1. We first looked
at the sex ratio; the gender distribution between
patients and controls was found to be significantly
different (P = 1×10−3). The mean age of KC patients
was 30.40 ± 11.33 (range 6–70 years), while the
mean age of the healthy group was 30.14 ±
9.29 (range, 19–62 years), there was no statically
significant difference in the mean age between the
two groups. Then, we were interested in the most
discriminating risk factors; we observed a clear
significant difference between cases and controls
concerning atopy, eye rubbing with a high number
of cases than controls also exposure to cigarette
smoke as risk factor but with a large number of
controls than cases (P = 1×10−6). KC patients had
more family history of the pathology than healthy
controls (21% vs 3%, P = 7×10−4). We also noted
that there was no statistically significant difference
between the case and control groups regarding
the consanguinity and ultraviolet radiation (UV)
exposure (P = 0.24 and 0.077, respectively).

The distribution of allele frequencies for the two
SNPs in control group did not deviate significantly
from HWE (P > 0.05). The details of gentotypic
and allelic frequencies are summarized in Table
3. The frequency distributions of IL4 rs2070874
genotypes between cases and controls revealed
no statistical significance (P = 0.44). The allelic
distribution of the polymorphism in the control
population revealed that the allele C of IL4
rs2070874 represents the major allele (0.83) and
the allele T represents the allele minor (0.17), there
were no significant differences in the frequency’s
distribution of the IL4 rs2070874 C/T alleles (P =
0.18) even in the presence of at least one copy of
the allele T of IL4 rs2070874 among the genotypes
(P = 0.28).

The distributions of genotype’s frequencies of
FOXP3 rs3761548 in KC cases were: GG, 46%; GT,

JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021 561



Keratoconus Associated Genes in Algeria; Meteoukki et al

37%; and TT, 17%; and the distribution in control
group were: GG, 47%; GT, 36%; and TT, 17%.
No significant association was observed between
KC patients and healthy controls concerning
FOXP3 rs3761548 genotypes (P = 0.98), the allele
frequency distribution was also nonsignificant (P
= 0.9; OR = 1.03; 95%CI [0.63–1.68]), with minor T
allele frequency 0.35 and major G allele frequency
0.65. The presence of at least one copy of the allele
T of FOXP3 rs3761548 showed nonsignificant
association between cases and controls (P = 0.86;
OR = 1.06; 95%CI [0.55–2.05]).

DISCUSSION

We investigated the impacts of the most
discriminating risk factors and IL4 rs2070874
and FOXP3 rs3761548 polymorphisms on a group
of KC patients and controls from Western Algeria.
To the best of our knowledge, this is the first study
on the impact of IL4 and FOXP3 polymorphisms in
a population originating from Algeria.

Our results showed a higher female prevalence
in our study population (P = 0.001). This female
predominance of KC found in our sample is the
opposite of what is found in the literature. Some
studies have shown a male predominance among
patients from the United States,[23] while others
have shown no significant difference.[24] These
results remain to be confirmed on a larger number
of patients in order to be able to explain this female
predominance in our population [Table 1].

The mean age in our sample of patients is
equivalent to that found in several studies that
demonstrate that KC usually affects adolescents at
puberty as well as young adults until the fourth
decade of life.[25] The mean age of KC cases
in our study was 30.40 ± 11.33 years [Table
1], which fits perfectly with the study of Cozma
et al[26] concerning the White patient group in his
work about the influence of ethnic origin on the
incidence of KC.

In our sample, there was a significant difference
between cases and controls groups concerning
family history with KC (P = 7×10−4) [Table 1]. Indeed,
the familial link with KC represents a serious risk
factor,[27] since Gordon-Shaag et al showed that the
risk of developing KC was 15 to 67 times higher
compared to the general population.[28] In addition,
they reported that 5 to 27.9% of patients with KC
had a positive family history.[28]

Consanguinity has also been proposed as a
risk factor of KC in Israeli Arabs and Palestinian
Arabs,[28–30] as studies have shown that the
high number of consanguineous marriages among
Muslims is a cause of the increased incidence of
KC.[31] However, we did not find any significant
difference between cases and controls in our
population for this factor (P = 0.24) [Table 1]; this
could be caused by the small number of KC
patients group.

For more than 50 years, atopy has been
identified as a risk factor.[32] In addition, several
studies have shown that asthma and allergy are
associated with KC with statistical significance
(P = 0.0008 for asthma and 0.04 for allergy).[7]
Our results correlate with this work since in our
sample, atopy was reported in 69% of cases
compared to 16% in controls with a statistically
significant difference (P = 1×10−6) [Table 1], knowing
that all patients are from Western Algeria – a
coastal region known for its humid and marine
climate and neighboring industrial areas. A study
in the region of Eastern Algeria confirmed that
climatology would increase the risk of developing
allergic diseases, and atopy based on family criteria
was very common in this population.[33]

Another risk factor is related to patients’ habits,
the eye rubbing. The rubbing of the eyes is
currently the most important risk factor that is
clearly identified. This risk factor triggers the onset
and progression of the disease through several
effects, including the stimulation of inflammation.
Most authors report that approximately half of the
KC patients rub their eyes, although this varies
with the usual duration of rubbing and that the
rubbing of the eyes is mild or vigorous.[28, 34] The
results of our study are in perfect correlation with
the literature. We have shown that 80% of patients
with KC rubbed their eyes regularly compared to
1% in controls. Thus, in our sample, eye rubbing
seems to be associated with the appearance of
the KC (P = 1×10−6) [Table 1]. Indeed, several
studies have attempted to explain the involvement
of this risk factor in the development of KC. In
fact, the micro-trauma caused to the epithelium by
the eye rubbing generates high levels of matrix
metalloproteases (MMP-1 and MMP-13) secreted by
the epithelial and stromal cells, in addition, the
release of inflammatory mediators (IL-6 and TNF-
α) is one of the processes leading to KC and its
progression.[35]

562 JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021



Keratoconus Associated Genes in Algeria; Meteoukki et al

In our sample, we found that there was no
statistically significant difference between the case
and control groups concerning sun exposure risk
factor (P = 0.07) [Table 1]. Studies have shown
that the prevalence of KC is higher in sunny
countries than in Europe or North America, high
sun exposure in these countries would explain the
high prevalence of KC.[27] In addition to the genetic
component, UV light has an additive effect by
causing oxidative damage which would be among
the causes of the acceleration of the pathological
process of KC.[28] However, it should be noted that
UV could provide, at a controlled dose, a beneficial
effect by inducing the reticulation of corneal
collagen, thus attenuating the development or
progression of the disease.[36]

In 2008, a study was able to demonstrate for the
first time that cigarette smoking appeared to have
a protective effect against KC.[37] Our results seem
to support this hypothesis, since in our sample,
we observed a greater frequency of smoking in
controls (84%) compared to KC patients (39%).
Moreover, this difference is statistically significant
(P = 1×10−6) [Table I], and exposure to cigarette
smoke appears to have a protective effect (OR = 0.1
[0.055–0.269]). Other studies concluded that there
was no significant association between smoking
and KC.[30]

The hypothesis of testing the effect of the IL4
rs2070874 and FOXP3 rs3761548 polymorphisms
in the predisposition to KC development is based
on the fact that these polymorphisms known
to be associated with allergies could be either
directly associated with the development of KC
or indirectly, via inflammation induced by micro-
trauma due to eye rubbing.[34] Indeed, our results
[Table 1] showed that atopy and eye rubbing in
patients with KC were significantly associated with
the pathology in our study sample (P = 1×10−6)
[Table 1].

According to our results, the T allele of IL4
rs2070874 represents the minor allele (0.17) [Table
3]. This allelic distribution is close to the findings
of a study performed in 2018 on a sample of 58
subjects in the Western Algeria (0.10).[38] The same
observation was reported in other populations
such as Italians (0.12),[39] Swedish, Australian,
Finnish, and English populations (0.16).[40] This
frequency is lower than that reported in the African-
Americans (0.43)[41] and Indians (0.39).[42] However,
the T allele of FOXP3 rs3761548 represents the
minor allele with a frequency of 0.35 [Table 3].

This minor allele frequency (MAF) is in line with the
Egyptian study (0.34),[43] but different from those
reported in Turkish and Indian populations, 0.61
and 0.56, respectively.[44, 45] This variability in the
results of the studies may be due to ethnic factors
and the size of the sample studied [Table 3].

Our case–control study suggests no association
between (IL4 rs2070874, FOXP3 rs3761548)
polymorphisms and susceptibility to KC, even in
the presence of at least one copy of the allele T
of IL4 rs2070874 or T allele of FOXP3 rs3761548
[Table 3]. According to Bawazeer et al,[34] allergy
is indirectly associated with the development of
KC and its effect is probably due to inflammation
caused by rubbing eye movements. These results,
once confirmed in a larger cohort, would be
further evidence.[34] Indeed, most authors report
that about half of the patients with KC rub their
eyes regularly, although the percentage varies
among studies.[28] It is interesting to note that in
cases of asymmetric KC, the most affected eye
has been rubbed the most vigorously.[46] Coyle
et al reported the case of an 11-year-old boy who
at the age of 5, discovered that he could stop
his tachycardia by vigorously massaging his left
eye (up to 20 min/day).[47] At age 7, he hadn’t
developed anything in his eyes. At the age of 11,
the child developed unilateral KC in only his left
eye which was massaged vigorously. Another case
of KC has been reported in a patient with a history
of vigorous daily massage of the left eye which
led to unilateral KC in that eye only.[48] A series
of cases confirms the asymmetrical expression of
the disease in patients who usually rub the most
affected eye.[46, 49, 50]

Thus, eye rubbing would cause micro-trauma
leading to the secretion of high levels of MMP.[35]
These factors can lead to progression of KC
associated with apoptosis of keratocytes,[51] and
atopic episodes can contribute and interact with
other inflammatory processes related to KC.[52]

This is the first demonstration of the
implication of susceptibility genes to allergy in
the development of KC, and this is the first time
that the IL4 and FOXP3 genes association was
analyzed with KC risk in an Algerian population.

Our results showed that there would be a
significant association in our study sample
between risk factors such as family history
with disease, atopy and eye rubbing, and KC
development. In addition, our results confirmed

JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021 563



Keratoconus Associated Genes in Algeria; Meteoukki et al

that smoking would provide a protective effect
against the pathology. However, it has been
shown that there is no association between the IL4
rs2070874 and FOXP3 rs3761548 polymorphisms
and the occurrence of KC in the population
of Western Algeria. However, because of the
moderate size of the sample, the statistical power
of the present study was relatively low, being
50% and 59% for the IL4 rs2070874 and FOXP3
rs3761548 polymorphisms, respectively.

In summary, our results provide precise and up-
to-date information on the association of the two
polymorphisms studied with KC in the population
of Western Algeria. The small size of our study
requires a replication of the results in a larger
sample of the population in order to confirm or
affirm the association. Nevertheless, the present
study does not exclude the effect of IL4 and FOXP3
gene polymorphisms in the pathophysiological
process of the KC disease. For this reason, the
present study may be considered as a pilot study.

Financial Support and Sponsorship

Nil.

Conflicts of Interest

There are no conflicts of interest.

REFERENCES

1. Krachmer JH, Feder RS, Belin MW. Keratoconus and
related noninflammatory corneal thinning disorders. Surv
Ophthalmol 1984;28:293–322.

2. Lema I, Sobrino T, Durán JA, Brea D, Díez-Feijoo E.
Subclinical keratoconus and inflammatory molecules from
tears. Br J Ophthalmol 2009;93:820–824.

3. Jun AS, Cope L, Speck C, Feng X, Lee S, Meng H, et al.
Subnormal cytokine profile in the tear fluid of keratoconus
patients. PLoS ONE 2011;6:e16437.

4. Davidson AE, Hayes S, Hardcastle AJ, Tuft SJ. The
pathogenesis of keratoconus. Eye Lond Engl 2014;28:189–
195.

5. Harrison RJ, Klouda PT, Easty DL, Manku M, Charles J,
Stewart CM. Association between keratoconus and atopy.
Br J Ophthalmol 1989;73:816–822.

6. McMonnies CW, Boneham GC. Keratoconus, allergy,
itch, eye-rubbing and hand-dominance. Clin Exp Optom
2003;86:376–384.

7. Nemet AY, Vinker S, Bahar I, Kaiserman I. The
association of keratoconus with immune disorders.
Cornea 2010;29:1261–1264.

8. Bijlsma FJ, van Kuik J, van Hoffen E, de Jonge N,
Tilanus MGJ, Gmelig-Meyling FHJ, et al. Acute cardiac
transplant rejection is associated with low frequencies
of interleukin-4 producing helper T-Lymphocytes rather
than with interleukin-4 promoter or splice variants. Hum
Immunol 2002;63:317–323.

9. Vijayanand P, Seumois G, Simpson LJ, Abdul-Wajid S,
Baumjohann D, Panduro M, et al. Interleukin-4 production
by follicular helper T cells requires the conserved Il4
enhancer hypersensitivity site V. Immunity 2012;36:175–
187.

10. Harada Y, Tanaka S, Motomura Y, Harada Y, Ohno S,
Ohno S, et al. The 3′ enhancer CNS2 is a critical regulator
of interleukin-4-mediated humoral immunity in follicular
helper T cells. Immunity 2012;36:188–200.

11. Movahedi M, Amirzargar AA, Nasiri R, Hirbod-Mobarakeh
A, Farhadi E, Tavakol M, et al. Gene polymorphisms of
interleukin-4 in allergic rhinitis and its association with
clinical phenotypes. Am J Otolaryngol 2013;34:676–681.

12. Gervaziev YV, Kaznacheev VA, Gervazieva VB. Allelic
polymorphisms in the interleukin-4 promoter regions and
their association with bronchial asthma among the Russian
population. Int Arch Allergy Immunol 2006;141:257–264.

13. Suzuki I, Hidaka N, Yamaguchi E, Kawakami Y. Association
between a C+33T polymorphism in the IL-4 promoter
region and total serum IgE levels. Clin Htmlent Glyphamp
Asciiamp Exp Allergy 2000;30:1746–1749.

14. Yang H-J. Association between the interleukin-4 gene C-
589T and C+33T polymorphisms and asthma risk: a meta-
analysis. Arch Med Res 2013;44:127–135.

15. Denyer MP, Pinheiro DY, Garden OA, Shepherd AJ.
Missed, not missing: phylogenomic evidence for the
existence of avian FOXP3. Pappalardo F, éditeur. PLoS
ONE 2016;11:e0150988.

16. Maruyama T, Konkel JE, Zamarron BF, Chen W. The
molecular mechanisms of FOXP3 gene regulation. Semin
Immunol 2011;23:418–423.

17. Zhang L, Zhang Y, Desrosiers M, Wang C, Zhao Y, Han
D. Genetic association study of FOXP3 polymorphisms
in allergic rhinitis in a Chinese population. Hum Immunol
2009;70:930–934.

18. Fodor E, Garaczi E, Polyánka H, Koreck A, Kemény L, Széll
M. The rs3761548 polymorphism of FOXP3 is a protective
genetic factor against allergic rhinitis in the Hungarian
female population. Hum Immunol 2011;72:926–929.

19. World Medical Association. World Medical Association
Declaration of Helsinki: Ethical Principles for
Medical Research Involving Human Subjects. JAMA
2013;310:2191–2194.

20. Hollingsworth JG, Efron N. Observations of banding
patterns (Vogt Striae) in keratoconus: a confocal
microscopy study. Cornea 2005;24:162–166.

21. Brożek JL, Bousquet J, Agache I, Agarwal A, Bachert C,
Bosnic-Anticevich S, et al. Allergic Rhinitis and Its Impact
on Asthma (ARIA) guidelines – 2016 revision. J Allergy Clin
Immunol 2017;140:950–958.

22. Miller SA, Dykes DD, Polesky HF. A simple salting out
procedure for extracting DNA from human nucleated cells.
Nucleic Acids Res 1988;16:1215.

23. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and
epidemiologic study of keratoconus. Am J Ophthalmol
1986;101:267–273.

564 JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021



Keratoconus Associated Genes in Algeria; Meteoukki et al

24. Li X, Rabinowitz YS, Rasheed K, Yang H. Longitudinal
study of the normal eyes in unilateral keratoconus patients.
Ophthalmology 2004;111:440–446.

25. Rabinowitz YS. Keratoconus. Surv Ophthalmol
1998;42:297–319.

26. Cozma I, Atherley C, James NJ. Influence of ethnic origin
on the incidence of keratoconus and associated atopic
disease in Asian and White patients. Eye 2005;19:924–
925.

27. Moussa S, Grabner G, Ruckhofer J, Dietrich M, Reitsamer
H. Genetics in keratoconus – what is new? Open
Ophthalmol J 2017;11:201–210.

28. Gordon-Shaag A, Millodot M, Shneor E, Liu Y. The genetic
and environmental factors for keratoconus. BioMed Res Int
2015;2015:795738.

29. Barbara R, Gordon-Shaag A, Millodot M, Shneor E, Essa M,
Anton M. Prevalence of keratoconus among young Arab
students in Israel. Int J Keratoconus Ectatic Corneal Dis
2014;3:9–14.

30. Gordon-Shaag A, Millodot M, Essa M, Garth J, Ghara M,
Shneor E. Is consanguinity a risk factor for keratoconus?
Optom Vis Sci 2013;90:448–454.

31. Georgiou T, Funnell CL, Cassels-Brown A, O’Conor R.
Influence of ethnic origin on the incidence of keratoconus
and associated atopic disease in Asians and White
patients. Eye 2004;18:379–383.

32. Galvis V, Sherwin T, Tello A, Merayo J, Barrera R,
Acera A. Keratoconus: an inflammatory disorder? Eye
2015;29:843–859.

33. Boumendjel A, Tridon A, Ughetto S, Messarah M,
Salah Boulakoud M. Environnement allergénique d’une
population d’enfants asthmatiques à Annaba (Algérie). Ann
Biol Clin (Paris) 2010;68:317–324.

34. Bawazeer AM, Hodge WG, Lorimer B. Atopy and
keratoconus: a multivariate analysis. Br J Ophthalmol
2000;84:834–836.

35. Balasubramanian SA, Pye DC, Willcox MD. Effects of eye
rubbing on the levels of protease, protease activity and
cytokines in tears: relevance in keratoconus: eye rubbing
in keratoconus. Clin Exp Optom 2013;96:214–218.

36. Chan E, Snibson GR. Current status of corneal collagen
cross-linking for keratoconus: a review: cross-linking and
keratoconus. Clin Exp Optom 2013;96:155–164.

37. Spoerl E, Raiskup-Wolf F, Kuhlisch E, Pillunat LE. Cigarette
smoking is negatively associated with keratoconus. J
Refract Surg 2008;24:S737–S740.

38. Rahmoun N, El Mecherfi KE, Bouchetara A, Lardjem Hetraf
S, Dahmani Amira C, Adda Neggaz L, et al. Association

of REL polymorphism with cow’s milk proteins allergy
in pediatric Algerian population. Fetal Pediatr Pathol
2018;37:74–83.

39. Vargiolu M, Silvestri T, Bonora E, Dolzani P, Pulsatelli L,
Addimanda O, et al. Interleukin-4/interleukin-4 receptor
gene polymorphisms in hand osteoarthritis. Osteoarthr
Cartil 2010;18:810–816.

40. FitzGerald LM, Zhao S, Leonardson A, Geybels MS, Kolb
S, Lin DW, et al. Germline variants in IL4, MGMT and AKT1
are associated with prostate cancer-specific mortality: an
analysis of 12,082 prostate cancer cases. Prostate Cancer
Prostatic Dis 2018;21:228–237.

41. Battle NC, Choudhry S, Tsai H-J, Eng C, Kumar G, Beckman
KB, et al. Ethnicity-specific gene–gene interaction
between IL-13 and IL-4Rα among African Americans with
asthma. Am J Respir Crit Care Med 2007;175:881–887.

42. Majumder P, Panda SK, Ghosh S, Dey SK. Interleukin
gene polymorphisms in chronic periodontitis: a case–
control study in the Indian population. Arch Oral Biol
2019;101:156–164.

43. Elsohafy M, Elghzaly A, Abdelsalam H, Gaballah M.
Assessment of the possible role of FOXP3 gene
(rs3761548) polymorphism in psoriasis vulgaris
susceptibility and pathogenesis: Egyptian study. Indian
Dermatol Online J2019;10:401.

44. Cekin N, Pinarbasi E, Bildirici AE, Donmez G, Oztemur
Z, Bulut O, et al. FOXP3 rs3761548 polymorphism is
associated with knee osteoarthritis in a Turkish population.
Int J Rheum Dis 2018;21:1779–1786.

45. Jahan P, Ramachander VRV, Maruthi G, Nalini S, Latha KP,
Murthy TSR. FOXP3 promoter polymorphism (rs3761548)
in breast cancer progression: a study from India. Tumor
Biol 2014;35:3785–3791.

46. Zadnik K, Steger-May K, Fink BA, Joslin CE, Nichols
JJ, Rosenstiel CE, et al. Between-eye asymmetry in
keratoconus. Cornea 2002;21:671–679.

47. Terrence Coyle J. Keratoconus and eye rubbing. Am J
Ophthalmol 1984;97:527–528.

48. Gritz DC, McDonnell PJ. Keratoconus and ocular massage.
Am J Ophthalmol 1988;106:757–758.

49. Jafri B, Lichter H, Stulting RD. Asymmetric keratoconus
attributed to eye rubbing. Cornea 2004;23:560–564.

50. Koenig SB. Bilateral recurrent self-induced keratoconus.
Eye Contact Lens Sci Clin Pract 2008;34:343–344.

51. Rehany U, Lahav M, Shoshan S. Collagenolytic activity in
keratoconus. Ann Ophthalmol 1982;14:751–754.

52. McMonnies CW. Inflammation and keratoconus. Optom
Vis Sci Off Publ Am Acad Optom 2015;92:e35–e41.

JOURNAL OF OPHTHALMIC AND VISION RESEARCH VOLUME 16, ISSUE 4, OCTOBER-DECEMBER 2021 565