Intrafamilial Transmission of Rosacea Spanning Six Generations: A Retrospective Observational Study.

Rosacea hereditary predisposition has been hypothesized based on family inheritance and twin concordance. Currently, information concerning intrafamilial rosacea transmission are still limited to few generations. The aim of our study was to assess data on rosacea intrafamilial transmission spanning six generations. One-hundred and thirty patients affected by rosacea who visited our acne and rosacea clinic from June 2018 to June 2019 were consecutively enrolled in this study. During clinical evaluation, an accurate anamnesis, including familiarity across six generations, which included vertical, horizontal, and combined transmission, was performed. Affected relatives were clinically evaluated, and in those in which clinical consultation was not feasible, clinical photos were obtained. The results showed that 64 of 130 patients (49.2%) were positive for at least a family member with rosacea. In addition, 90 affected relatives (69.2%) were identified by extending the familial investigation to the whole kindred, finding a percentage of familiarity (69.2%) higher than that reported in the literature (30-50%) with a 1:1.4. ratio of patients positive for familiarity/affected relative. Our study contributes to add knowledge about intrafamilial involvement in rosacea. Extending the search to all potential affected parents and offspring of rosacea patients can promote early diagnosis along with the adoption of correct therapeutic interventions and educational programs to prevent the exposure to triggering or exacerbating factors.