Most reports on the dental findings in PWS have focused on the presence of rampant caries, tooth wear, delayed tooth eruption, and hypoplastic enamel [
4‐
6]. However, little is known about periodontal diseases in PWS. To the best of our knowledge, the only report in the English literature concerned a case of early-onset periodontitis in a 12-year-old girl with PWS [
7]. The present report demonstrates the presence of moderate-to-severe periodontal destruction in a patient with PWS.
Several researchers have reported severe periodontal diseases in patients with systemic genetic disorders such as Marfan syndrome (MFS), Ehlers-Danlos syndrome (EDS) and Down's syndrome (DS), which are accompanied by connective tissue disorders characterized by joint hypermobility and scoliosis. MFS is caused by mutations in the fibrillin-1 gene on chromosome 15q21.1, leading to abnormalities in the connective tissue matrix [
8]. Straub
et al. reported that inflammatory periodontal breakdown in a patient with MFS was caused by abnormalities in the periodontal connective tissue rather than being attributable to the primary biochemical changes of MFS [
9]. EDS comprises a heterogeneous group of inherited connective tissue disorders characterized by joint laxity, chronic joint pain, skin hyperextensibility, tissue fragility and scoliosis [
10]. EDS can be divided into 11 phenotypes, and periodontal diseases have been reported in EDS types I and VIII. The pathogeneses of these subtypes of EDS are unknown. The periodontal disease in EDS type I is localized, whereas EDS type VIII is characterized by ligneous periodontitis or persistent hyperplastic gingivitis [
11]. DS is a chromosomal disorder that results from an extra copy of chromosome 21 (trisomy 21). Patients with DS have a variety of associated medical conditions, including joint hypermobility and ligamentous laxity [
12]. The immune alternations in DS, including impaired neutrophil chemotactic function, are responsible for the defensive mechanisms in periodontal disease, which are frequently experienced by subjects with DS [
13,
14]. As in MFS, EDS and DS, musculoskeletal abnormalities such as scoliosis, joint hyperlaxity, delayed bone age and osteoporosis, are also clinical features of PWS [
3]. Although a number of imprinted genes have been mapped to the PWS region at 15q11.2-q13, there is no case normal paternal copy of 15q11-q13 with inheritance consistent with a single mutated gene, suggesting that PWS is a multigenic syndrome [
15]. Furthermore, there is no gene related to the connective tissue matrix in the PWS region. The periodontal breakdown demonstrated in this case report may have been the combined result of poor plaque control, crowding, tooth malposition, and occlusal trauma. In particular, the presence of plaque and inflammation in our patient would appear to be a primary etiology, with occlusal imbalances as a contributing factor. Additionally, the interactions of multiple genes affected in PWS may increase the susceptibility to periodontal breakdown via effects on the host immune response; a recent report has shown that an overactivation of the innate immune system and increased chronic low-grade inflammation has been observed in patients with PWS [
16]. Periodontal disease in PWS, as shown in this report, is considered to be similar to cases of patients with DS with regard to traumatic occlusion, mouth breathing with an open bite, poor plaque control and immune alternations. Further studies are needed to clarify the relationship between the genetic defect(s) and periodontal disease in PWS.
A recent study that surveyed the orodental characteristics of 15 patients with PWS with early multidisciplinary follow-up at the university hospital reported low incidence of caries and enamel hypoplasia [
6]. However, our patient did not receive a multidisciplinary medical follow-up, and it is possible that such follow-up, including dental procedures, could have prevented the development of periodontal disease and caries. Learning disabilities in individuals with PWS mean that prolonged treatments such as periodontal surgery with local anesthesia or oral self-care with several cleaning aids such as tooth brushing, inter-dental brushing and dental flossing, which require tolerance and technique on the part of the patient, are hardly applicable. Thus, oral preventive treatments or interventions from early childhood, such as optimal plaque control and occlusal improvement by orthodontic treatments, should be implemented and may be beneficial for patients with PWS.