Novel homozygous mutations in the osteoprotegerin gene TNFRSF11B in two unrelated patients with juvenile Paget's disease
BONE
Authors: Naot, Dorit; Choi, Ally; Musson, David Shaun; Kiper, Pelin Ozlem Simsek; Utine, Gulen Eda; Boduroglu, Koray; Peacock, Munro; DiMeglio, Linda A.; Cundy, Tim
Abstract
Most patients with juvenile Paget's disease (JPD) are homozygous for mutations in the gene TNFRSF11B that result in deficiency of osteoprotegerin (OPG) a key regulator of bone turnover. So far, about 10 different OPG mutations have been described. The current study presents two novel OPG mutations in JPD patients. Patient 1 was diagnosed at the age of 9 months when he presented with inability to sit up, slow growth, marked bone pain and very high levels of serum alkaline phosphatase. Patient 2 presented a milder phenotype. He was initially diagnosed with osteogenesis imperfecta, and although he had numerous fractures and bone deformity, he was still independently mobile at the age of 19 years, when a diagnosis of JPD was confirmed. Sequence analysis of DNA samples from the patients determined two novel homozygous mutations in TNFSRF11B. Patient 1 (severe phenotype) had a large (245-251 kbp) homozygous deletion beginning in intron 1 that resulted in loss of 4 of the 5 exons of TNFSRF11B, including the whole ligand-binding domain. Patient 2 had a homozygous missense mutation resulting in a Thr > Pro change in exon 2 of TNFSRF11B that is predicted to disrupt the OPG ligand-binding domain. Taken in conjunction with other published cases, these results are consistent with the hypothesis that the most severe phenotypes in JPD are seen in patients with major gene deletions or mutations affecting cysteine residues in the ligand-binding domain. (C) 2014 Elsevier Inc. All rights reserved.
Dental Caries, Developmental Defects of Enamel and Enamel Microhardness Associated with Genetic Polymorphisms in the RANK/RANKL/OPG System
JOURNAL OF CLINICAL PEDIATRIC DENTISTRY
Authors: Calvano Kuchler, E.; Maschietto Pucinelli, C.; Carpio Horta, K.; Assed Bezerra da Silva, R.; de Castro Costa, M.; Rezende Vieira, A.; Nelson-Filho, P.; Assed Bezerra da Silva, L.; Santos Antunes, L.; Azeredo Antunes, L.
Abstract
Purpose: Recent studies have suggested that disruptions in the RANKL/RANK/OPG system might be involved in enamel conditions. The aim of this study was to test whether genetic polymorphisms in RANK, RANKL and OPG are associated with dental caries, developmental defects of enamel (DDE) and enamel microhardness. Study design: Saliva samples were collected from two subsets for the purpose of genomic DNA extraction. In the first subset, composed of 248 children, dental caries and DDE were evaluated during their clinical examination. In the second subset, composed of 72 children, enamel samples from the buccal surface of primary teeth were used for enamel microhardness analysis. Genetic polymorphisms in RANK, RANKL and OPG were genotyped by real-time polymerase chain reactions in all samples from both populations. The chisquare test was used for dental caries and DDE analysis while, one-way ANOVA with Tukey's post-test was used for microhardness analysis. Hardy-Weinberg equilibrium was also calculated. The established alpha was 5%. Results: Caries experience analysis demonstrated a statistically-significant difference for OPG allele distribution in primary dentition (p=0.033). The studied polymorphisms in RANK, RANKL and OPG were not associated with DDE or enamel microhardness (p>0.05). Conclusion: The genetic polymorphism rs2073618 in OPG is associated with dental caries experience in primary dentition.