الفهرس 
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Abstract
Vitiligo is an acquired and idiopathic progressive mucocutaneous
disease characterized by damage to working epidermal melanocytes. Vitiligo
is categorized as SV and NSV. In NSV genetic factors of increased risk of
autoimmunity were discovered by a genome-wide study.
External signals like light or external temperature synchronize or alter
the human circadian system, which is regulated by a central cardiac
pacemaker situated in the suprachiasmatic nucleus of the anterior
hypothalamus, which is essential for the preservation of numerous
physiological, endocrine, and behavioral activities, as body temperature, cell
cycle regulation, the sleep-wake cycle and hormone secretion.
Circadian genes have critical functions in gene expression regulation,
such as cell proliferation, apoptosis, DNA repair, and cell cycle control.
Among these genes ARNTL-1 gene which is found on chromosome 11p15.3
and plays a role as a pivotal transcriptional regulator in cellular homeostasis.
It is well-recognized that circadian dysfunction underlies the
pathogenesis of inflammatory diseases. So, the purpose of this study was to
determine the link between ARNTL-1 gene expression and polymorphism
with NSV, and its effect on lipid profile.
The type of this study is a case-control. It included 50 non-related
patients presented with NSV and aged ≥ 18 years and age-matched healthy
individuals having no family history of vitiligo (No=50) comprised the
controls. The studied cases were subjected to a full history and clinical
examination. The vitiligo area scoring index was calculated using this
formula: VASI = (all body sites) (hand units) × (depigmentation). The
vitiligo disease activity score was based on the patient’s own opinion of
his/her disease activity over time.
Summary
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Laboratory investigations included: the detection of lipid profile (TC,
TG, HDL, and LDL), ARNTL-1 gene expression from cDNA samples
generated from RNA extracted from blood samples using real-time PCR, and
detection of ARNTL-1 polymorphism (rs2279287) by real-time PCR.
The results of the current study revealed that:
There was a significantly higher TC, TG, and LDL, but significantly
lower HDL serum levels in NSV patients than in controls (p<0.0001).
The ARNTL-1gene expression was significantly higher in NSV
patients than in controls (p<0.0001).
The ARNTL-1 rs2279287 gene polymorphism showed a significant
difference between NSV patients and controls. TC genotype was
present in 92% of NSV patients versus 68% in controls while TT
genotype was present in 8% of NSV patients versus 32% in controls.
TC genotype significantly increased the risk for NSV by about 2 folds.
Relative quantification of ARNTL-1 gene at Cutoff ≥1.16 can
significantly predict NSV with a sensitivity of 78%, specificity of
84%, and accuracy of 81%.
There were significant positive correlations between RQ level of
ARNTL-1 gene and the vitiligo patient’s age, age of onset, and VIDA
Score.
VIDA score was statistically significantly higher in patients with T/C
genotype than in T/T genotype.
The level of ARNTL-1 gene was significantly higher in NSV patients
with T/C genotype than in T/T genotype.