Vitiligo is a benign, chronic autoimmune disorder characterized by idiopathic, stable, or progressive depigmentation of the skin. It results from the loss of melanocytes, affects individuals of all races, and remains one of the most challenging dermatological conditions to treat worldwide [1]. The global prevalence of vitiligo varies across regions, ranging from 0.1% to 2.0% of the population [2].
The global distribution of RhD phenotypes is influenced by race, ethnicity, environmental factors, and migration patterns across populations [3]. Although RhD status is primarily associated with alloimmunization in pregnant women, leading to hemolytic disease of the newborn [4], it may also play a role in the pathogenesis of various other conditions. For instance, a Canadian study suggested that the RhD− blood group may be associated with a reduced risk of SARS-CoV-2 infection [5], whereas the RhD+ antigen has been linked to pregnancy-induced hypertension [6] and increased susceptibility to HIV [4] in Sweden and Denmark. Additionally, a study conducted in the Czech Republic reported that the RhD phenotype modulates the influence of age and smoking on human behavior and physiology [7].
The objective of this letter is to present the results of our study investigating whether a statistically significant association exists between vitiligo and the RhD blood group, including its relationship with age of onset and gender, in Turkey.
This case–control study included 234 patients with vitiligo and was conducted at the Department of Dermatology,Yeditepe University Hospital, Istanbul. Patient records, including age, sex, age of disease onset, and Rh blood group, were retrieved from the hospital’s electronic database. Patients of foreign nationality and those with incomplete records were excluded. The control group consisted of 8,664 blood donors who presented to the hospital’s Blood Bank. The study design was approved by the Ethics Committee of Yeditepe University (Approval No. 202312Y0727), and all procedures were conducted in accordance with the principles of the Declaration of Helsinki.
Statistical analyses were performed using SPSS V22.0 software (IBM Inc., Armonk, NY, USA). Descriptives are presented as mean, median, standard deviation and percentage. A χ2 test was employed to ascertain whether there was a statistically significant difference between categorical variables. A p-value below 0.05 was regarded as statistically significant.
Among the 234 patients with vitiligo (123 males, 52.6%; 111 females, 47.4%), the distribution of RhD+ and RhD– blood groups was 88.9% and 11.1%, respectively, compared with 86.4% and 13.6% among 8,664 controls. The odds ratio (OR) for vitiligo in individuals with the RhD+ blood group, relative to controls, was 1.26 (95% CI: 0.84–1.91; p = 0.27).
Among male patients with vitiligo, the distribution of RhD+ and RhD– blood groups was 87.8% and 12.2%, respectively, whereas in female patients it was 90.1% and 9.9%. The association between gender and RhD status in vitiligo patients was not statistically significant (χ² test, p > 0.05).
The mean age of onset among RhD+ patients (n = 208) was 33.4 ±17.0 years, with a median of 34.0 years (range: 0–90 years; IQR: 21 years). In comparison, RhD– patients (n = 26) had a mean onset age of 31.2 ±16.0 years and a median of 30.5 years (range: 6–60 years; IQR: 22 years). Similar to the gender-based analysis, no statistically significant association was observed between RhD status and age of onset in vitiligo (independent samples t-test, p > 0.05).
To our knowledge, this is the first study in Turkey to investigate a potential association between vitiligo and RhD status. Our findings are consistent with those of a recently published report [8].
Regardless of RhD status, red blood cells contain the homologous RhCE/RHCE protein and Rh-associated glycoprotein (RhAG/RHAG). Therefore, in RhD– individuals, RhCE/RHCE and RhAG/RHAG may compensate for the absence of RhD, which could explain the limited associations observed with RhD status [9].
In conclusion, no statistically significant differences were observed in the distribution of RhD blood groups between vitiligo patients and controls (p > 0.05). Similarly, no significant association was found between gender and RhD status among vitiligo patients, nor between RhD status and age of disease onset.
