Cuban patients with suggestive clinical presentation of xeroderma pigmentosum and normal biochemical markers of disease

Background: Xeroderma pigmentosum is a rare disease; however, it is important to be aware of it and differentiate it in current clinical practice due to its significant clinical heterogeneity. It can range from mild to moderate sensitivity to ultraviolet radiation to extreme photosensitivity and skin cancer at an early age. Objective: To describe the biochemical markers that allow the exclusion of the diagnosis of xeroderma pigmentosum in patients with suggestive clinical presentation Method: Cross-sectional descriptive study that included 12 Cuban patients with a presumptive diagnosis of xeroderma pigmentosum, established by a multidisciplinary national medical commission. They presented with photodamage of varying intensity, with signs of chronic actinic damage and/or premalignant lesions or skin cancer. A clinical-biochemical algorithm was applied for disease diagnosis: DNA repair capacity with ultraviolet C radiation was evaluated using alkaline comet assay, and eta polymerase expression was determined using Western blot assay. Blood lymphocytes were used. Key results: DNA repair capacity was normal in all patients (52.4% to 131.7%), indicating a competent repair phenotype. The protein band observed in the Western blot showed normal expression of eta polymerase. Consequently, the diagnosis of the disease was excluded. The variability observed in repair combined with the clinical characteristics suggested a differentiated analysis in patients with 50% to 60% repair rates. Conclusion: The normal biochemical markers analyzed allowed the exclusion of xeroderma pigmentosum diagnosis in a group of patients with signs of chronic actinic damage, premalignant lesion or skin cancer.