Abstract
BACKGROUND: A wide variation of phenotypes is displayed by individuals with alopecia areata (AA), especially in the paediatric population. OBJECTIVES: To systematically search published studies to identify paediatric syndromes with AA and their clinical features, and to summarize the current state of their genetic elucidation. METHODS: In accordance with the PRISMA guidelines, a systematic search of MEDLINE, Embase, CENTRAL and PubMed databases was performed. All original case reports, case series and observational studies describing AA in children (aged <18 years) with monogenic or chromosomal syndromes were included. Further searches in OMIM and Orphanet, and reviews, clinical guidelines and basic science studies were used to retrieve additional comprehensive information on each syndrome. RESULTS: After title and abstract screening of 1426 studies, and full-text review of 224 studies, 64 met the inclusion criteria and are summarized in this review. Overall, the search identified 33 genetic syndromes with paediatric AA. Prevalence estimates were available for 79% (n = 26/33) of syndromes, with 45% (n = 15/33) of syndromes presenting in fewer than 1/1 000 000 individuals. Sixty-seven per cent (n = 22/33) of syndromes were fully genetically elucidated; 12% (n = 4/33) were partially elucidated; 9% (n = 3/33) were not genetically elucidated; and 12% (n = 4/33) were syndromes with chromosomal abnormalities. Seventy-nine per cent (n = 26/33) of syndromes were described by only one report, while 21% (n = 7/33) were described in multiple independent reports. CONCLUSIONS: Despite the limited knowledge of these syndromes, this review provides insights into the range of genetic syndromes with paediatric AA and their clinical features, facilitating early prediction, diagnosis and personalized treatments.