Epidemiology and Clinical Characteristics of Harlequin Ichthyosis: A Systematic Review and Meta-Analysis of Case Reports

Introduction: Harlequin ichthyosis (HI) is considered one of the rarest and most severe congenital disorders, characterized by the development of thick, plate-like scales, ectropion, eclabium, and multisystem complications that mainly cause high neonatal mortality. Objectives: This systematic review and meta-analysis aimed to comprehensively summarize all reported global case reports and series of harlequin ichthyosis, identifying common clinical presentations and geographic and genetic trends, and evaluating outcomes of different treatment approaches to inform better management strategies for this rare disease. Methods: A comprehensive search across different databases using different predefined terms was conducted; only case reports and case series in English were included in this review. Results: The review was conducted among 56 case studies and case series, including 68 cases that revealed that 64.7% had an unspecified genetic mutation, while 30.9 % carried an ABCA12 mutation. The clinical manifestations among the patients were severe, including thick scales, reported in 79.4% of the patients, ectropion, reported in 80.9% of them, and eclabium, which was reported in 79.4% of the patients. Despite the supportive care received by the patients, the mortality rate was as high as 60.3%, with an average age at death of 47.19 days. Treatment response varied among the patients, with only 30.9% of them showing clinical improvement. Conclusion: Our review highlights the significantly high morbidity and mortality rates associated with a diagnosis of HI, indicating the need for early diagnosis, genetic counseling, and improvement in the management strategies.