HOPP Syndrome

Hypotrichosis-osteolysis-periodontitis-palmoplantar keratoderma syndrome, aka HOPP syndrome, is a rare ectodermal dysplasia disorder characterized by hypotrichosis, reticular palmoplantar keratoderma, periodontitis, and acro-osteolysis (Van Steensel 2009; Van Steensel et al. 2002). Papillon-Lefevre syndrome (PLS) and its allelic variant, Haim-Munk syndrome, resemble the presentations of HOPP syndrome; however, both resulted from mutations in the cathepsin C gene (CTSC) which is not detected in HOPP syndrome (Van Steensel et al. 2002). In addition to the lack of mutation in CTSC, CTSK, or CTSL, HOPP syndrome can be differentiated from PSL by its manifestations such as acro-osteolysis, arachnodactyly, and pes planus (Van Steensel et al. 2002). The prevalence of the disorder is extremely low (<1/1,000,000) and only three cases have been reported up to date: the first two cases are a mother and her daughter from the Netherlands and the third case is from Venezuela (Van Steensel 2009; Van Steensel et al. 2002; Brun and van Steensel 2004). The age of onset is reported to be neonatal/infancy.