Ethnicity and stratum corneum ceramides

BACKGROUND: The barrier function of the skin is dependent on an optimal composition of the stratum corneum lipids, exemplified by the altered lipid profile in patients with atopic eczema (AE). Differences in the global prevalence of AE point to the environment as an important factor in AE. Studies on filaggrin point to a genetic aspect in AE. The influence of environment and genes needs to be explored. OBJECTIVES: To investigate possible differences in stratum corneum lipids between different healthy ethnicities living in the same environment. METHODS: Healthy participants without any major skin diseases were enrolled in the study. Twenty-five participants of Asian origin (Asians), 18 of African origin (Africans) and 28 of Danish origin (white-skinned), all students at universities in the Copenhagen area of Denmark, had the ceramide profile of their stratum corneum examined using the cyanoacrylate method and analysed using high-performance thin layer chromatography. RESULTS: For the ceramide/cholesterol ratio we found statistically significant differences between groups, with Asians having the highest ratio (P <0·001 as compared with both white-skinned individuals and Africans), white-skinned individuals having intermediate values, and Africans having the lowest values. No statistically significant differences were found between any of the ceramide subgroups. CONCLUSIONS: We found different ceramide/cholesterol ratios in comparable groups of different ethnicity, pointing to unknown genetic differences.