ABSTRACT Background: The association of leptin (LEP) and vascular endothelial growth factor A (VEGFA) genes with the susceptibility to knee osteoarthritis (OA) has been analyzed; however, the epistasis between them has not been investigated. Objective: The objective of the study was to analyze the association of LEP and VEGFA variants and their interaction with primary knee OA in a Mexican Mestizo population. Methods: A case-control study was developed. Cases were ≥40 years, BMI ≤27 kg/m2, with primary knee OA and radiologic Grade ≥2. Controls were participants with no knee OA and a radiologic Grade <2. The rs2167270 of LEP and rs2010963 of VEGFA were genotyped. Genotypic association was tested under codominant, dominant, and recessive models. Uni- and multi-variate analyses were developed through non-conditional logistic regression. The multifactor dimensionality reduction algorithm was developed to detect epistasis. Results: Participants comprised 103 cases and 179 controls. Allelic and genotypic distributions did not show differences between the groups. Notwithstanding, a statistically significant interaction was observed between the LEP and VEGFA genes (p = 0.02) with a testing accuracy of 0.5199 and cross-validation consistency of 10/10. This interaction model confers an increased risk to knee OA (OR [95% CI] = 1.8 [1.1-2.9]). Conclusion: Interaction between LEP and VEGFA is related with genetic susceptibility to developing primary knee OA.

Abstract Background: Primary Osteoarthritis (OA) of the knee is a multifactorial disease that has an important genetic component, and several genes have been associated with its development. The vitamin D receptor has a role in skeletal metabolism that suggests a relationship with OA. The aim of this study was to analyze the association of Vitamin D receptor gene (VDR) polymorphisms in Mexican Mestizo patients. Methods: A case-control study was conducted in which 107 cases with primary OA of the knee and 114 controls were included. Cases were patients > 40 years of age with a Body mass index (BMI) of ≤27 and a radiological score for OA of the knee of ≥2. Controls were subjects > 40 years of age with a radiological score of < 2. VDR polymorphisms rs1544410, rs7975232, and rs731236 were analyzed by means of restriction endonucleases, and logistic regression was developed to evaluate risk magnitude. Results: A significantly increased risk was found of nearly two-fold for the allele T and TT genotypes of rs731236, independently of other well recognized risk factors. Conclusions: The rs731236 polymorphism is associated with the risk of primary OA of the knee in Mexican Mestizo population.

Abstract:Background: It is well recognized that vitamin D has a direct effect in bone and muscle and has been associated as well with some rheumatologic diseases. Reports in children are scarce. The aim of this study was to determine the concentration level of 25(OH)D in a group of patients with systemic lupus erythematosus (SLE) and juvenile idiopathic arthritis (JIA) and compare them with healthy controls.Methods: Vitamin D (25(OH)D) was measured with isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS), PTH with immunoradiometric assay (IRMA), calcium, phosphorus and alkaline phosphatase by colorimetric assay in 37 patients with SLE, 37 patients with JIA and 79 healthy controls.Results: Mean 25(OH)D concentration levels were as follows: SLE 18.9 ± 7.92 ng/ml, JIA 21.97 ± 5.55 ng/ml and 23.6 ± 3.07 ng/ml in healthy controls. There was a significant difference between SLE patients vs. healthy controls (p <0.05); 29.7% of SLE patients, 35.1% of JIA patients and 31.6% of healthy controls had deficient levels of vitamin D.Conclusions: One third of the total sample of children in this study had deficient levels of vitamin D. Patients with SLE presented a significant difference compared with healthy controls.

Resumen:Introducción: Se sabe que la vitamina D (25(OH) D) tiene un efecto directo sobre la salud del hueso y músculo. Se ha relacionado también con enfermedades reumatológicas de origen autoinmune. Los estudios en niños con este tipo de enfermedades son escasos, sobre todo en artritis idiopática juvenil. El objetivo de este trabajo fue determinar las concentraciones de 25(OH) D en pacientes con lupus eritematoso sistémico (LES) y artritis idiopática juvenil (AIJ), y compararlas con las concentraciones en individuos sanos.Métodos: Se determinaron las concentraciones de 25(OH) D por medio de espectrometría de masas con cromatografía liquida por tándem (ID-LC-MS/MS), las concentraciones de la hormona paratiroidea por análisis inmunorradiométrico (IRMA), y las concentraciones de calcio, fósforo y fosfatasa alcalina por métodos colorimétricos en 37 pacientes con LES, 37 pacientes con AIJ y 79 controles sanos.Resultados: Las concentraciones séricas de 25(OH) D fueron de 18.9 ±7.92 ng/ml en LES, 21.97 ± 5.55 ng/ml en AIJ y 23.6 ± 3.07 ng/ml en controles sanos. Hubo una diferencia significativa al comparar las concentraciones de 25 (OH) D entre los pacientes con LES y los controles sanos (p <0.05). El 29.7% de pacientes con LES, el 35.1% con AIJ y el 31.6% de sujetos sanos cursaron con niveles deficientes de vitamina D en este estudio.Conclusiones: Una tercera parte de los niños estudiados en los tres grupos mostraron deficiencias de vitamina D. La más severa fue en los niños con LES.