Effectiveness of Socially Assistive Robots in Promoting Positive Emotional Responses and Alleviating Postoperative Pain Among Children: Quantitative Study.

Papillon–Lefèvre syndrome is characterized by the association of autosomal recessive transgressive palmoplantar keratosis, which begins in early childhood, and rapidly progressive periodontitis during the prepubertal period. The prevalence of this genodermatosis is reported to range from 1 to 4 cases per million, leading to frequent delays in diagnosis in pediatric dentistry (). Central to the pathogenesis are loss-of-function mutations in the cathepsin C () gene in the 11q14.1–q14.3 region (). This enzymatic deficiency weakens the host defense against periodontal pathogens and is accompanied by loss of function in chemotaxis and phagocytosis steps in neutrophils (). Mechanistically, cathepsin C (dipeptidyl peptidase I) is required to proteolytically activate the pro-forms of neutrophil serine proteases, namely neutrophil elastase, proteinase 3, and cathepsin G, within maturing neutrophils; in its absence, these effector enzymes remain catalytically inactive, compromising intracellular killing of ingested pathogens (). Although periodontal and cutaneous disease dominate the classical phenotype, isolated reports have described visceral abscesses, most often hepatic, in patients with PLS, indicating that deep-seated infection is a rare but recognized part of the clinical spectrum (, ). The International Union of Immunological Societies (IUIS) classification of inborn errors of immunity lists deficiency (Papillon–Lefèvre syndrome) among the congenital defects of phagocyte number or function within the inborn errors of immunity group (, ). Clinically, the onset of keratosis between the first and fourth years of life frequently coincides with the eruption of primary teeth; gingival inflammation, deep periodontal pockets, and prominent fetor develop rapidly, leading to tooth mobility and premature tooth loss. The existing literature on PLS consists largely of isolated case reports, with limited data on within-family phenotypic variability or on the diagnostic yield of systematic cascade screening following an index diagnosis. Family members sharing the same biallelic variant may differ substantially in disease severity — from life-threatening deep-space infection to subclinical skin changes alone — a variability that complicates clinical recognition and underscores the value of molecular confirmation and structured family evaluation.