The skin is the largest organ in the body. Its function is to protect the body from potential harm and to maintain homeostasis. The epidermis is the outermost layer of the skin. Stratum corneum is the outermost layer of the epidermis, composed of corneocytes and surrounding lipids. The lipids are produced by different enzymes that all play a role in the formation and function of the skin permeability barrier. Mutations in genes coding for these enzymes can lead to barrier dysfunction and could cause autosomal recessive congenital ichthyosis (ARCI). Nine genes have been identified as ARCI-causative and two of them are CYP4F22 and CERS3.   The purpose of this project was to study co-localization of CYP4F22 with CERS3 and also mutated CYP4F22 enzymes, by transfecting plasmids into HeLa and HaCaT cells and performing PLA on HEKn cells. Co-localization could indicate potential interactions and by studying these more in the future, novel treatment strategies can be developed for ARCI patients.   Transfection attempts showed a low transfection grade of wild type genes in both HeLa and HaCaT cells. Tendencies towards co-localization was seen in both cell types and some HeLa cells showed strong correlation after image analysis. Transfection of mutated genes failed, unfortunately. PLA showed co-localization in normal keratinocytes. The obtained results indicated a co-localization, but results need to be confirmed by immunoprecipitation and immunoblotting in the future.