Background: Xeroderma pigmentosum (XP) is a rare DNA damage repair disorder. Seven distinct complementation groups and an XP variant form have been identified; however, limited literature exists on the genotype-phenotype correlation in XP.
Objectives: To explore the manifestations of XP variants in patients from Türkiye.
Methods: Our multicentric investigation involved 69 patients with XP from 52 unrelated families across 12 centres in Türkiye. Clinical examinations and genetic tests were conducted to assess the correlation between variants and disease characteristics.
Results: Of the XP groups, XP-C was the most prevalent (n = 38; 55%), followed by XP-variant (n = 15; 22%), XP-E (n = 8; 12%), XP-D (n = 4; 6%), XP-A (n = 3; 4%) and XP-G (n = 1; 1%). XP-B and XP-F were not identified. Median patient age at diagnosis was 9 years (interquartile range 2-19), although this varied significantly according to complementation group, with XP-D and XP-V diagnoses occurring later. Genetic analyses revealed 30 novel variants, including one in a patient with XP/Cockayne syndrome complex. Despite the link of XP-D to neurological degeneration, none of the patients showed neuropathy, while three patients with XP-E had neurological involvement. Notably, 26% (n = 18) of patients reported no consanguinity, yet a significant proportion (n = 11/18) had distant family members with XP.
Conclusions: We found unique clinical patterns and diversity among complementation groups in Turkish patients with XP. Future investigations should focus on functional characterization of the novel variants, preferably through assays like unscheduled DNA synthesis, to determine their potential impact on DNA repair mechanisms and their implications for improved patient care.
Xeroderma pigmentosum is a rare genetic condition where the body does not properly repair the damage caused by sunlight. People with the condition often develop severe sunburns after a short time in the sun. Over time, they are much more likely to develop certain skin cancers at a young age. The condition can also cause other changes to the skin and cancers of different organs. In some cases, it can cause problems with the nervous system. In this study, we looked at how different genetic changes affect the way the condition shows up in patients from Türkiye. We included 69 patients from hospitals in Türkiye. Dermatologists (skin doctors) examined the patients and genetic testing was done to find out which type of XP the patients had. Most patients examined had a type of the condition called ‘XP-C’. The age at which patients were diagnosed with the condition varied greatly by the type of xeroderma pigmentosum they had. We also found new gene variants (what we used to call ‘genetic mutations’). This means the condition can look very different depending on a person’s specific genetics. We need more research to better understand the effects of the new gene variants found and how this may help improve patient care.
© The Author(s) 2026. Published by Oxford University Press on behalf of British Association of Dermatologists.