SUMMARY & CONCLUSION
Vitiligo is a common idiopathic skin disease characterized by selective destruction of melanocytes leading to depigmentation in the form of milky white macules or patches. Vitiligo occurs worldwide with an estimated prevalence of 0.5–1%. In almost half of the patients, vitiligo starts before the age of 20 years, however, it can be seen at any age group with no significant sex difference.
Although the etiopathogenesis of vitiligo is not yet fully understood, the autoimmune, auto cytotoxic, neural, and biochemical-based hypotheses are considered. Although environmental factors are important, there is considerable evidence that genes also play a significant role in its pathogenesis. Strong evidence from twin and family studies indicates the importance of genetic factors in the development of vitiligo, although it is clear that these influences are complex.
Recently, several hundred novel genes encoding transcripts containing short double-stranded RNA hairpins, named miRNAs, were identified in plants and animals. MiRNAs are a class of small non-coding RNAs that regulate gene expression primarily through translational repression. The exact mechanism by which target genes are down-regulated remains unclear.
It was found that miRNA 196a-2 polymorphism contributes to pathogenesis of variety of diseases and is possible genetic predisposing factor. Recently, miRNA196a2 was found to be associated with coronary artery disease, increased risk of cardiovascular disease, cerebrovascular stroke, deregulated in various malignancies and implicated in some infectious diseases as HCV.
This study aimed to investigate the association between a functional single nucleotide polymorphism (SNP) of rs 11614913 in microRNA 196a-2 and the serum tyrosinase level in vitiligo patients and evaluate the effect of this polymorphism on the response to treatment. Also, the current study tried to explore the presence of microRNA 196a-2 polymorphism in first degree relatives of vitiligo patients as a predictor of susceptibility to develop the disease.
The current study was a prospective case-control interventional study that was conducted on patients with vitiligo in Benha University Hospital. This study was conducted on 100 participants. Fifty of them were patients with vitiligo, and they were located in group 1. Group 2 contained 50 control participants, twenty five out of them were 1st-degree relatives for vitiligo patients (group 2a), while the other 25 had a negative family history.
In group 1, the patients assessed with full history taking, general and dermatological examination with photographic documentation. The severity of the condition was assessed by rule of nine and VASI score. Then blood samples were taken for laboratory investigations. Determination of the miRNA 196a-2 polymorphism with PCR as well as assay of the serum level of tyrosinase enzyme using ELISA. Then, they were treated for 4 months by NB-UVB with the regimen of twice weekly sessions with the starting fixed dose of 200mJ/cm2 irrespective to skin type with increment in dose by about10-20% per session unless side effects were appearing. Then after the end of the treatment course, serum tyrosinase level was remeasured and the response of the treatment was evaluated objectively through VASI score and subjectively through estimating the patient satisfaction.
Group 2 was tested also for the type of miRNA 196-a2 polymorphism and the serum level of Tyrosinase enzyme to be compared with the first group.
Qualitative data were summarized in the form of frequency and percentage. Mean and SD were obtained for quantitative data, while categorical data were presented by number and percentage. One way analysis of variance (ANOVA) test, paired and independent sample t-tests were used for comparing means between groups. Tests used for association were Chi square (X2) or Mont-Carlo Exact test (MCET). P -value was adopted to be |
