La variante missense rs2908004 de WNT16 actúa como eQTL de FAM3C en osteoblastos primarios humanos / WNT16 rs2908004 missense variant acts as eQTL of FAM3C in human primary osteoblasts

Introducción: WNT16 es un gen importante en la homeostasis ósea, que se encuentra en un locus muy complejo que también incluye los genes vecinos: ING3. FAM3C y CPED1. Además del claro papel de WNT16 sobre la determinación de la densidad mineral ósea (DMO), también se han encontrado pruebas sobre la importancia de estos tres genes vecinos en el metabolismo óseo. Queda por tanto esclarecer si las variantes en WNT16 asociadas a la DMO realizan su efecto propiamente sobre WNT16 o si lo hacen modificando la expresión de estos genes vecinos. Material y métodos: Hemos determinado los niveles de expresión de CPED1 y FAM3C en osteoblastos primarios y hemos comprobado si variantes de WNT16 se comportan como loci de rasgos cuantitativos de expresión (expresion quantitative trait loci; eQTL) de estos genes. Resultados: La variante de cambio de aminoácido rs2908004 en WNT16 actúa como eQTL de FAM3C en osteoblastos primarios bajo la hipótesis de modelo dominante. Discusión: Es posible que el efecto de esta variante sobre la DMO sea debido a la modificación de los niveles de expresión de FAM3C además o en vez de un efecto directo de la proteína WNT16 mutante resultante del cambio de aminoácido. (AU)

Introduction: WNT16 is an important gene in bone homeostasis, found in a very complex locus that also includes neighboring genes: ING3, FAM3C, and CPED1. In addition to the clear role of WNT16 in determining bone mineral density (BMD), evidence has also been found for the importance of these three neighboring genes in bone metabolism. Therefore, it remains to be clarified whether the variants in WNT16 associated with BMD carry out their effect on WNT16 or if they do so by modifying the expression of these neighboring genes. Material and methods: We have determined the expression levels of CPED1 and FAM3C in primary osteoblasts and we have verified whether WNT16 variants behave as loci of quantitative expression traits (expression quantitative trait loci; eQTL) of these genes. Results: The amino acid change variant rs2908004 in WNT16 acts as the eQTL of FAM3C in primary osteoblasts under the dominant model hypothesis. Discussion: It is possible that the effect of this variant on BMD is due to the modification of the expression levels of FAM3C in addition to or instead of a direct effect of the mutant WNT16 protein resulting from the amino acid change. (AU)

Búsqueda de variantes del gen LRP4 en mujeres con alta masa ósea y en pacientes con malformación de Chiari tipo I / Search for variants of the LRP4 gene in women with high bone mass and in patients with Chiari type I malformation

Objetivo: LRP4 es un facilitador esencial en la inhibición específica de esclerostina de la vía canónica de Wnt. Mutaciones en LRP4 se han asociado a diversas patologías entre las cuales se incluyen la patología de crecimiento óseo, esclerosteosis y la malformación de Chiari tipo I (MCI). Material y métodos: Se ha re-secuenciado el gen LRP4 en dos pequeñas cohortes de pacientes con el fenotipo de alta masa ósea (HBM) y con MCI con el objetivo de encontrar variantes causales. Resultados: Entre las mutaciones encontradas destacamos: 1) una mutación de cambio de sentido (missense) en un paciente con MCI, que no cosegrega con el fenotipo en la familia; 2) una mutación intrónica no descrita previamente (c.3364+16A>C) en una mujer con HBM; y 3) una mutación intrónica en una mujer con HBM cuya frecuencia en población control europea es muy baja. Conclusión: Aunque no hemos encontrado variantes en LRP4 que expliquen el fenotipo HBM o MCI en los pacientes estudiados, animamos a otros investigadores a que analicen el gen LRP4 en sus pacientes ya que es un buen candidato funcional de ambos fenotipos. (AU)

Objetive: LRP4 is an essential facilitator in sclerostin-specific inhibition of the canonical Wnt pathway. Mutations in LRP4 have been associated with various conditions, including bone growth disease, sclerosteosis, and Chiari type I malformation (CMI). Material and methods: The LRP4 has been re-sequenced in two patient cohorts with high bone mass phenotype (HBM) and with CMI aimed at finding causal variants. Results: Among the mutations found, we would highlight: 1) a missense mutation in a patient with CMI, which does not co-segregate with the phenotype in the family; 2) a previously undescribed intronic mutation (c.3364+16A>C) in a woman with HBM; and 3) an intronic mutation in a woman with HBM with a very low frequency in the European control population. Conclusion: Although we have not found variants in LRP4 to explain the HBM or CMI phenotype in the patients studied, we encourage other researchers to analyze the LRP4 gene in their patients as it is a good functional candidate for both phenotypes. (AU)

A Spanish adaptation of the Quality in Psychiatric Care - Inpatient Staff (QPC-IPS) instrument: Psychometric properties and factor structure / Adaptación española de Calidad en la Atención en Salud Mental - Instrumento para los Profesionales de Hospitalización (QPC-IPS): propiedades psicométricas y estructura factorial

BACKGROUND: Western countries share an interest in evaluating quality of care in the healthcare field. In spite of this, there is a lack of intercultural comparison of the perceptions of professionals. One reason for this may be the lack of standardized instruments. The objective of this study was to investigate the psychometric properties and dimensions of the Spanish version of the Quality in Psychiatric Care-Inpatients Staff (QPC-IPS) instrument. METHODS: After translation and revision of the instrument by a panel of experts, a questionnaire was obtained in Spanish that was administered to a pilot sample. A total of 163 professionals participated in the study. RESULTS: After conducting pilot testing and a cognitive interview with 30 professionals, it was determined that the QPC-IPS was adequate and could be self-administered. Confirmatory factor analysis confirmed six factors that explained 60.9% of the variation. In terms of internal consistency, a Cronbach's alpha of 0.92 was obtained for the full instrument. For test retest reliability, the intraclass correlation coefficient for the overall questionnaire was 0.91. Convergent validity was analyzed using the NTP394 satisfaction instrument, yielding a positive correlation (0.58). CONCLUSIONS: The results demonstrated that the psychometric properties in terms of internal consistency, temporal stability (test-retest), content validity, and construct validity (confirmatory factor analysis) were adequate. These results confirm that the structure of the Spanish version is similar to the original Swedish version of the QPC-IP

FUNDAMENTO: Los países occidentales comparten un interés en evaluar la calidad de la atención en el campo de la salud. A pesar de esto, existe una falta de comparación intercultural de las percepciones de los profesionales. Una razón para esto puede ser la falta de instrumentos estandarizados. El objetivo de este estudio fue investigar las propiedades psicométricas y las dimensiones de la versión española del instrumento Quality in Psychiatric Care-Inpatients Staff (QPC-IPS). MÉTODOS: Tras la traducción y revisión del instrumento por un panel de expertos se obtuvo un cuestionario en español que fue administrado a una muestra piloto. La muestra estuvo configurada por 163 profesionales. RESULTADOS: Después de realizar una prueba piloto y una entrevista cognitiva con 30 profesionales, se determinó que el QPC-IPS era adecuado y podía autoadministrarse. El análisis factorial confirmatorio confirmó seis factores que explican el 60,9% de la varianza. Mediante el análisis de consistencia interna, se obtuvo un alfa de Cronbach de 0,92 para el total del instrumento. Para la fiabilidad del test-retest, el coeficiente de correlación intraclase para el cuestionario general fue de 0,91. La validez convergente se analizó utilizando el instrumento de satisfacción NTP394, produciendo una correlación positiva (0,58). CONCLUSIONES: Los resultados demostraron que las propiedades psicométricas en términos de consistencia interna, estabilidad temporal (test-retest), validez de contenido y validez de constructo (análisis factorial confirmatorio) fueron adecuadas

A Spanish adaptation of the Quality in Psychiatric Care - Inpatient Staff (QPC-IPS) instrument: Psychometric properties and factor structure.

BACKGROUND: Western countries share an interest in evaluating quality of care in the healthcare field. In spite of this, there is a lack of intercultural comparison of the perceptions of professionals. One reason for this may be the lack of standardized instruments. The objective of this study was to investigate the psychometric properties and dimensions of the Spanish version of the Quality in Psychiatric Care-Inpatients Staff (QPC-IPS) instrument. METHODS: After translation and revision of the instrument by a panel of experts, a questionnaire was obtained in Spanish that was administered to a pilot sample. A total of 163 professionals participated in the study. RESULTS: After conducting pilot testing and a cognitive interview with 30 professionals, it was determined that the QPC-IPS was adequate and could be self-administered. Confirmatory factor analysis confirmed six factors that explained 60.9% of the variation. In terms of internal consistency, a Cronbach's alpha of 0.92 was obtained for the full instrument. For test re-test reliability, the intraclass correlation coefficient for the overall questionnaire was 0.91. Convergent validity was analyzed using the NTP394 satisfaction instrument, yielding a positive correlation (0.58). CONCLUSIONS: The results demonstrated that the psychometric properties in terms of internal consistency, temporal stability (test-retest), content validity, and construct validity (confirmatory factor analysis) were adequate. These results confirm that the structure of the Spanish version is similar to the original Swedish version of the QPC-IP.

Estudio genético de la fractura femoral atípica mediante la secuenciación del exoma en tres hermanas afectas y tres pacientes no relacionadas / Genetic study of atypical femoral fractures using exome sequencing in three affected sisters and three unrelated patients

Objetivos: Las fracturas atípicas de fémur (FAF) son un tipo de fracturas poco frecuentes, a menudo relacionadas con un tratamiento prolongado con bisfosfonatos (BPs). Actualmente no se conocen con exactitud sus mecanismos patogénicos y no hay pruebas para identificar aquellos pacientes con un alto riesgo de sufrir una FAF. El objetivo de este trabajo es investigar las bases genéticas de las FAFs. Material y métodos: Se secuenció el exoma completo de 3 hermanas y de 3 pacientes adicionales no relacionadas, todas tratadas con BPs durante más de 5 años. Se seleccionaron variantes compartidas por las hermanas, de baja frecuencia y potencialmente patogénicas, y se construyó una red de interacciones de genes y proteínas con los datos hallados. Resultados: Identificamos 37 variantes raras (en 34 genes) compartidas por las 3 hermanas, algunas de ellas no descritas anteriormente. La variante más llamativa fue la mutación p.Asp188Tyr en el enzima geranilgeranil pirofosfato sintasa (codificada por el gen GGPS1), de la vía del mevalonato y esencial para la función del osteoclasto. Otro hallazgo interesante fueron dos mutaciones (una en las 3 hermanas y una en una paciente no relacionada) en el gen CYP1A1, implicado en el metabolismo de los esteroides. Identificamos otras variantes que también podrían estar involucradas en la susceptibilidad a las FAFs o en el fenotipo osteoporótico subyacente, tales como las presentes en los genes SYDE2, NGEF, COG4 y la FN1. Conclusiones: Nuestros datos son compatibles con un modelo donde la acumulación de variantes de susceptibilidad podría participar en la base genética de las FAF

Objectives: Atypical femoral fractures (AFF) are rare, often related to long-term bisphosphonate (BPs) treatment. Their pathogenic mechanisms are not precisely known and there is no evidence to identify patients with a high risk of AFF. The aim of this work is to study the genetic bases of AFFs. Material and methods: Whole-exome sequencing was carried out on 3 sisters and 3 unrelated additional patients, all treated with BPs for more than 5 years. Low frequency, potentially pathogenic variants shared by the 3 sisters, were selected, were selected and a network of gene and protein interactions was constructed with the data found. Results: We identified 37 rare variants (in 34 genes) shared by the 3 sisters, some not previously described. The most striking variant was the p.Asp188Tyr mutation in the enzyme geranylgeranyl pyrophosphate synthase (encoded by the GGPS1 gene), from the mevalonate pathway and essential for osteoclast function. Another noteworthy finding was two mutations (one in the 3 sisters and one in an unrelated patient) in the CYP1A1 gene, involved in the metabolism of steroids. We identified other variants that could also be involved in the susceptibility to AFFs or in the underlying osteoporotic phenotype, such as those present in the SYDE2, NGEF, COG4 and FN1 genes. Conclusions: Our data are compatible with a model where the accumulation of susceptibility variants could participate in the genetic basis of AFFs

Estudios funcionales de variantes de DKK1 presentes en la población general / Functional studies of DKK1 variants present in the general population

Objetivo: En las últimas décadas se han identificado genes asociados a la masa ósea y al riesgo de fractura osteoporótica, varios de los cuales pertenecen a la vía de Wnt. En este proyecto se estudió la funcionalidad de 7 mutaciones de cambio de sentido del gen DKK1 -un inhibidor de la vía de Wnt- presentes en la población general. Material y métodos: Se realizaron estudios in vitro del gen reportero luciferasa para medir la actividad de la vía de Wnt en presencia o ausencia de DKK1 silvestre o mutada, y estudios de western blot, para evaluar si las distintas mutaciones afectan a su síntesis y/o a su estabilidad. Resultados: La proteína DKK1 con la variante p.Ala41Thr presenta menor actividad inhibidora de la vía en comparación con la proteína silvestre. También se observaron diferencias significativas entre los experimentos realizados en ausencia de DKK1 y los que incluyen DKK1 con la mutación p.Ala41Thr. Los western blots mostraron que la cantidad de proteína era similar para todas las variantes, tanto las mutadas como la silvestre, por lo que la pérdida de actividad de p.Ala41Thr no parecía deberse a falta de proteína. El resto de las mutaciones no presentaron un comportamiento diferente al de la proteína DKK1 silvestre. Conclusiones: La variante de cambio de sentido p.Ala41Thr de la proteína DKK1, con una frecuencia poblacional de 0,013%, presenta una pérdida parcial de su función inhibidora, que no es debida a la falta de expresión de ésta. Esta variante génica podría conllevar un aumento de la densidad mineral ósea en las personas de la población general portadoras de esta mutación

Objective: In recent decades, genes associated with bone mass and osteoporotic fracture risk have been identified, several of which belong to the Wnt pathway. In this project, the functionality of 7 missense mutations of the gene DKK1-an inhibitor of the Wnt pathway- present in the general population was studied. Material and methods: In vitro studies of the luciferase reporter gene were carried out to measure Wnt pathway activity in the presence or absence of wild-type or mutated DKK1, and western blot studies, to evaluate if the different mutations affect its synthesis and/or stability. Results: The DKK1 protein with the p.Ala41Thr variant shows lower pathway inhibitory activity compared to the wild-type protein. Significant differences were also observed between the experiments performed in the absence of DKK1 and those that include DKK1 with the p.Ala41Thr mutation. Western blots showed that the amount of protein was similar for all variants, both mutated and "wild-type, so the loss of p.Ala41Thr activity did not seem to be due to a lack of protein. The rest of the mutations did not show different behavior from that of the wild DKK1 protein. Conclusions: The missense variant p.Ala41Thr of the DKK1 protein, with a population frequency of 0.013%, shows a partial loss of its inhibitory function, which is not due to the lack of expression. This gene variant could lead to an increase in bone mineral density in those people in the general population who carry this mutation

[Clinical and molecular study in a family with multiple osteochondromatosis]. / Estudio clínico y molecular en una familia con osteocondromatosis múltiple.

We present two cases of a family with the diagnosis of multiple osteochondromatosis, which was confirmed by molecular study with nonsense in heterozygosis mutation c.1219CT, (p.Gln407Stop) in the EXT1 gene. In these cases, the Madelung deformity was presented in one patient as an uncommon finding and chondrosarcoma as a feared complication in the other case, highlighting intrafamilial variation, which is why individual and interdisciplinary evaluation is recommended. In addition, before a genetic entity should provide adequate and timely family genetic counseling to all its members.

Se presentan dos casos de una familia con diagnóstico de osteocondromatosis múltiple, el cual fue confirmado por estudio molecular con mutación sin sentido en heterocigosis c.1219CT, (p.Gln407Stop) en el gen EXT1. En el primer caso, en un paciente se presentó deformidad de Madelung como hallazgo infrecuente y en el otro caso, condrosarcoma como complicación temida, resaltando la variación intrafamiliar, por lo que se recomienda la evaluación individual e interdisciplinaria. Además, ante una entidad genética debe brindarse el adecuado y oportuno asesoramiento genético familiar a todos sus integrantes.

Estudio clínico y molecular en una familia con osteocondromatosis múltiple / Clinical and molecular study in a family with multiple osteochondromatosis

Resumen: Se presentan dos casos de una familia con diagnóstico de osteocondromatosis múltiple, el cual fue confirmado por estudio molecular con mutación sin sentido en heterocigosis c.1219C>T, (p.Gln407Stop) en el gen EXT1. En el primer caso, en un paciente se presentó deformidad de Madelung como hallazgo infrecuente y en el otro caso, condrosarcoma como complicación temida, resaltando la variación intrafamiliar, por lo que se recomienda la evaluación individual e interdisciplinaria. Además, ante una entidad genética debe brindarse el adecuado y oportuno asesoramiento genético familiar a todos sus integrantes.

Abstract: We present two cases of a family with the diagnosis of multiple osteochondromatosis, which was confirmed by molecular study with nonsense in heterozygosis mutation c.1219C>T, (p.Gln407Stop) in the EXT1 gene. In these cases, the Madelung deformity was presented in one patient as an uncommon finding and chondrosarcoma as a feared complication in the other case, highlighting intrafamilial variation, which is why individual and interdisciplinary evaluation is recommended. In addition, before a genetic entity should provide adequate and timely family genetic counseling to all its members.

Discrepancy between bone density and bone material strength index in three siblings with Camurati-Engelmann disease.

Camurati-Engelmann (CE) is a very rare disease affecting one in every million persons worldwide. It is characterized by an enlargement of long bones. We aimed to assess bone characteristics in three siblings with different tools. Even if there was an excess of bone density, quality seemed to be deteriorated. INTRODUCTION: CE disease is a rare monogenic disorder affecting approximately one in every million persons worldwide. It is mainly characterized by a progressive hyperostosis of the periosteum and endosteum of the diaphysis of long bones. Limited data are available about bone characteristics in these patients. In three siblings with CE disease, we aimed to assess bone mineral density (BMD) and trabecular bone score (TBS) by dual-energy X-ray absorptiometry (DXA) and material characteristics at tissue level using bone impact reference point indentation. METHODS: Clinical data were collected and a general laboratory workup was performed. At the lumbar spine and hip, BMD and TBS were measured using DXA imaging. Bone material strength index (BMSi) was measured by bone impact microindentation using an Osteoprobe instrument. RESULTS: All three cases had densitometric values consistent with high bone mass (sum of Z-score at the lumbar spine and hip > 4). Hip BMD was extremely high in all three siblings at both total hip and femoral neck, while at the lumbar spine, two of them had normal values but the third again had very high BMD. TBS values were in the normal range. In contrast, BMSi measurements were at low or very low levels, compared with normal controls. CONCLUSION: Despite strikingly increased BMD and normal microarchitecture, BMSi is affected in patients with CE. Microindentation could be an appropriate tool for assessing bone fragility in these patients. Bone disease in this group of patients requires further study to better understand the underlying regulatory mechanisms and their alterations.

Identificación de variantes genéticas asociadas con la densidad mineral ósea (DMO) en el gen FLJ42280 / Identification of genetic variants associated with bone mineral density (BMD) in the FLJ42280 gene

FLJ42280 es un posible gen de susceptibilidad a la osteoporosis. Distintos estudios de GWAs han identificado 4 SNPs no-codificantes en este gen que se asocian a la densidad mineral ósea (DMO) y el riesgo de fractura. Para descubrir la causa de la asociación entre estos SNPs y la osteoporosis, se realizó una búsqueda de variantes genéticas mediante resecuenciación de 28 kb que contienen el gen, en una selección truncada de mujeres con DMO muy baja (n=50) o muy alta (n=50) de la cohorte BARCOS (Barcelona Cohorte Osteoporosis, cohorte de mujeres postmenopáusicas de Barcelona). Las variantes encontradas se filtraron y se analizó su frecuencia en cada grupo. Se analizó el solapamiento de las variantes con elementos funcionales del proyecto ENCODE y también se calculó el desequilibrio de ligamiento entre los SNPs de la región. Finalmente, se hizo un análisis de eQTL de los 4 SNPs no-codificantes respecto a los niveles de expresión de genes cercanos a FLJ42280 en linfoblastos. Se seleccionaron 110 variantes. Las diferencias de sus frecuencias entre los dos grupos estuvieron por debajo del poder estadístico del diseño experimental. Sin embargo, 3 variantes solaparon con posibles enhancers y una solapó con un enhancer activo en osteoblastos (rs4613908). Se observó un fuerte desequilibrio de ligamiento entre los 4 SNPs no-codificantes y el SNP rs4613908, que pertenecen a un bloque que abarca el gen casi por completo. Ninguno de los SNPs no-codificantes mostró asociación con los niveles de expresión de genes cercanos a FLJ42280. En conclusión, el SNP rs4613908 podría estar implicado funcionalmente en la determinación de la DMO. Serán necesarios experimentos concretos para confirmarlo (AU)

FLJ42280 is a possible gene for susceptibility to osteoporosis. Different studies of GWAs have identified 4 non-coding SNPs in this gene associated with bone mineral density (BMD) and fracture risk. In order to ascertain the cause of the association between these SNPs and osteoporosis, we searched for genetic variants by resequencing the 28-kb gene, in a truncated selection of women with very low (n=50) or very high BMD (N=50) of the BARCOS cohort (Barcelona Cohort Osteoporosis, cohort of postmenopausal women in Barcelona). The variants found were filtered and their frequency analyzed in each group. The overlap of the variants with functional elements of the ENCODE project was calculated. Finally, an eQTL analysis of the 4 SNPs-coding was performed on the expression levels of FLJ42280 neighbor genes in lymphoblasts. In all, 110 variants were selected. The differences in their frequencies between the two groups were below the statistical power of the experimental design. However, three variants overlapped with possible enhancers and one overlapped with an active enhancer in osteoblasts (rs4613908). A strong linkage disequilibrium was observed between the 4 non-coding SNPs and the SNP rs4613908, which belong to a block spanning the gene almost completely. None of the non-coding SNPs showed association with the expression levels of FLJ42280 neighbor genes. In conclusion, the SNP rs4613908 could be involved functionally in determining BMD. Tangible experiments will be required to confirm this (AU)

Estudio del patrón de expresión de microRNAs en el hueso osteoporótico / Study of miRNAs expression patterns in osteoporotic bone

Objetivos: Identificar microRNAs (miRNAs) diferencialmente expresados en muestras óseas con fractura osteoporótica respecto a huesos sanos. Material y métodos: Se extrajo RNA total a partir de hueso trabecular fresco del cuello femoral de mujeres sometidas a reemplazo de cadera, ya sea debido a fractura osteoporótica (n=6) o por artrosis en ausencia de osteoporosis (según la DMO) (n=6). Las muestras se hibridaron en un array de miRNAs y se realizaron diagramas de PCA y de mapa de calor. Para la comparación de los niveles de expresión, se fijó como significativo un umbral de cambio de >1,5 veces y un valor p <0,05 en la t de Student (corregido para múltiples pruebas). Resultados: Tanto los análisis de PCA como el mapa de calor mostraron una agrupación de las muestras según si eran de fractura o no. Se detectaron 790 miRNAs en las muestras de hueso, 82 de los cuales estaban alterados en las muestras osteoporóticas. Tras la validación en otro panel de 6 muestras osteoporóticas y 6 no osteoporóticas mediante PCR a tiempo real de los miRNAs más significativos, y para los que existía un ensayo disponible, se confirmaron los miRNAs miR-320a y miR-22-3p. Estos dos miRNAs se detectaron en cultivos de osteoblastos primarios, aunque no mantenían el mismo patrón de expresión que en las muestras de hueso total. Conclusiones: Hemos demostrado que existen diferencias en la expresión de miRNAs en muestras con fractura osteoporótica, lo que abre nuevas perspectivas para la investigación y diseño de nuevas terapias (AU)

Objectives: To identify microRNAs (miRNAs) differentially expressed in bone samples with osteoporotic fracture compared with healthy bones. Methods: Total RNA was extracted from fresh trabecular bone of the femoral neck of women undergoing hip replacement surgery, either because to osteoporotic fracture (n=6) or in the absence of osteoarthritis osteoporosis (based on BMD) (n=6). The samples were hybridized on an array of miRNAs and PCA diagrams and heat map were made. To compare expression levels, >1.5 times and a value p<0.05 Student's T test (corrected for multiple testing) was set as a threshold of significant change. Results: Both PCA analysis and the heat map showed a samples grouping whether there was fracture or not. 790 were detected miRNAs in bone samples, 82 of which were altered in the osteoporotic samples. After validation in another panel of 6 samples 6 osteoporotic and non-osteoporotic by PCR real time of the most significant miRNAs, and for which there was a test available, the miRNAs, miR-320a and miR-22-3p were confirmed. These two miRNAs were detected in cultures of primary osteoblasts, although they did not maintain the same pattern of expression in total bone samples. Conclusions: We have shown that there are differences in the expression of miRNAs in samples with osteoporotic fracture. This opens prospects for research and design of new therapies (AU)

CYP11A1 expression in bone is associated with aromatase inhibitor-related bone loss.

Aromatase inhibitors (AIs) used as adjuvant therapy in postmenopausal women with hormone receptor-positive breast cancer cause diverse musculoskeletal side effects that include bone loss and its associated fracture. About half of the 391 patients treated with AIs in the Barcelona-Aromatase induced bone loss in early breast cancer cohort suffered a significant bone loss at lumbar spine (LS) and/or femoral neck (FN) after 2 years on AI-treatment. In contrast, up to one-third (19.6% LS, 38.6% FN) showed no decline or even increased bone density. The present study aimed to determine the genetic basis for this variability. SNPs in candidate genes involved in vitamin D and estrogen hormone-response pathways (CYP11A1, CYP17A1, HSD3B2, HSD17B3, CYP19A1, CYP2C19, CYP2C9, ESR1, DHCR7, GC, CYP2R1, CYP27B1, VDR and CYP24A1) were genotyped for association analysis with AI-related bone loss (AIBL). After multiple testing correction, 3 tag-SNPs (rs4077581, s11632698 and rs900798) located in the CYP11A1 gene were significantly associated (P<0.005) with FN AIBL at 2 years of treatment. Next, CYP11A1 expression in human fresh bone tissue and primary osteoblasts was demonstrated by RT-PCR. Both common isoforms of human cholesterol side-chain cleavage enzyme (encoded by CYP11A1 gene) were detected in osteoblasts by western blot. In conclusion, the genetic association of CYP11A1 gene with AIBL and its expression in bone tissue reveals a potential local function of this enzyme in bone metabolism regulation, offering a new vision of the steroidogenic ability of this tissue and new understanding of AI-induced bone loss.

A broad spectrum of genomic changes in latinamerican patients with EXT1/EXT2-CDG.

Multiple osteochondromatosis (MO), or EXT1/EXT2-CDG, is an autosomal dominant O-linked glycosylation disorder characterized by the formation of multiple cartilage-capped tumors (osteochondromas). In contrast, solitary osteochondroma (SO) is a non-hereditary condition. EXT1 and EXT2, are tumor suppressor genes that encode glycosyltransferases involved in heparan sulfate elongation. We present the clinical and molecular analysis of 33 unrelated Latin American patients (27 MO and 6 SO). Sixty-three percent of all MO cases presented severe phenotype and two malignant transformations to chondrosarcoma (7%). We found the mutant allele in 78% of MO patients. Ten mutations were novel. The disease-causing mutations remained unknown in 22% of the MO patients and in all SO patients. No second mutational hit was detected in the DNA of the secondary chondrosarcoma from a patient who carried a nonsense EXT1 mutation. Neither EXT1 nor EXT2 protein could be detected in this sample. This is the first Latin American research program on EXT1/EXT2-CDG.

Mutations in the EXT1 and EXT2 genes in Spanish patients with multiple osteochondromas.

Multiple osteochondromas is an autosomal dominant skeletal disorder characterized by the formation of multiple cartilage-capped tumours. Two causal genes have been identified, EXT1 and EXT2, which account for 65% and 30% of cases, respectively. We have undertaken a mutation analysis of the EXT1 and EXT2 genes in 39 unrelated Spanish patients, most of them with moderate phenotype, and looked for genotype-phenotype correlations. We found the mutant allele in 37 patients, 29 in EXT1 and 8 in EXT2. Five of the EXT1 mutations were deletions identified by MLPA. Two cases of mosaicism were documented. We detected a lower number of exostoses in patients with missense mutation versus other kinds of mutations. In conclusion, we found a mutation in EXT1 or in EXT2 in 95% of the Spanish patients. Eighteen of the mutations were novel.

Molecular characterization of five patients with homocystinuria due to severe methylenetetrahydrofolate reductase deficiency.

Methylenetetrahydrofolate reductase (MTHFR) plays a major role in folate metabolism. Disturbed function of the enzyme results in hyperhomocysteinemia and causes severe vascular and neurological disorders and developmental delay. Five patients suspected of having non-classical homocystinuria due to MTHFR deficiency were examined with respect to their symptoms, MTHFR enzyme activity and genotypes of the MTHFR gene. All patients presented symptoms of severe central nervous system disease. Two patients died, at the ages of 15 months and 14 years. One patient is currently 32 years old, and is being treated with betaine and folinic acid. The other two patients, with an early diagnosis and a severe course of the disease, are currently improving under treatment. MTHFR enzyme activity in the fibroblasts of four of the patients was practically undetectable. We found four novel mutations, three of which were missense changes c.664G> T (p.V218L), c.1316T> C (p.F435S) and c.1733T> G (p.V574G), and the fourth was the 1-bp deletion c.1780delC (p.L590CfsX72). We also found the previously reported nonsense mutation c.1420G> T (p.E470X). All the patients were homozygous. Molecular modelling of the double mutant allele (p.V218L; p.A222V) revealed that affinity for FAD was not affected in this mutant. For the p.E470X mutation, the evidence pointed to nonsense-mediated mRNA decay. In general, genotype-phenotype analysis predicts milder outcomes for patients with missense changes than for those in which mutations led to severe alterations of the MTHFR protein.

Polymorphisms and haplotypes across the osteoprotegerin gene associated with bone mineral density and osteoporotic fractures.

UNLABELLED: Osteoprotegerin plays a key role in bone remodelling. We studied the association between 24 polymorphisms and haplotypes on the OPG gene and bone mineral density and fractures. After multiple-testing correction, one SNP and two block-haplotypes were significantly associated with FN BMD. Two other block-haplotypes were associated with fracture. INTRODUCTION AND HYPOTHESIS: Osteoprotegerin (OPG) plays a key role in bone remodelling. Here we studied the association between polymorphisms and haplotypes on the OPG gene and bone mineral density (BMD) and fractures. METHODS: Twenty-four single nucleotide polymorphisms (SNPs) were selected to cover six haplotypic blocks and were genotyped in 964 postmenopausal Spanish women. Haplotypes were established with HaploStats. Association was analysed by GLM (for BMD) and logistic regression (for fractures) both at single SNP and haplotype levels. RESULTS: Upon adjustment for multiple testing (p < 0.0073), one of the SNPs (SNP #17, rs1032129) remained significantly associated with FN BMD (p = 0.001). Four block-haplotypes stood multiple-testing correction. Two remained associated with FN BMD and two with fracture. The association of block-4 haplotype "AC" (of SNPs #18 and #17) with FN BMD (p = 0.0002) was stronger than that of SNP#17 alone and was the best result overall. A global assessment of the results indicated that all the alleles and haplotypes with a protective effect, at p < 0.05, belonged to a frequent long-range haplotype. CONCLUSIONS: In conclusion, these results provide a detailed picture of the involvement of common variants and haplotypes of the OPG gene in bone phenotypes.

Polymorphisms in the interleukin-6 receptor gene are associated with bone mineral density and body mass index in Spanish postmenopausal women.

OBJECTIVE: Osteoporosis and obesity are complex diseases with a strong genetic component. Bone mineral density (BMD) and body mass index (BMI) linkage studies identified a locus at 1q21-23, where the interleukin-6 receptor (IL6R) gene is located. The IL6R and the gp130 receptors are the mediators of IL6 action. Serum levels of IL6 and sIL6R (the soluble form of IL6R) are higher in several diseases such as osteoporosis or obesity. Variants at IL6R have been associated with BMI and obesity. However, IL6R is an as-yet-unexplored osteoporosis candidate gene. DESIGN: In the present study we analysed two polymorphisms in the IL6R promoter, -1435 C/T (rs3887104) and -208 G/A (rs4845617), and the Asp358Ala polymorphism (rs8192284), in relation to both BMD and BMI in a cohort of 559 postmenopausal Spanish women. RESULTS: The promoter polymorphisms, -1435 C/T and -208 G/A were associated with femoral neck (FN) BMD (P=0.011 and P=0.025 respectively). The C-A and T-G promoter haplotypes were also associated with FN BMD. Additionally, the Asp358Ala variant was associated with lumbar spine BMD (P=0.038). Finally, the -208 G/A polymorphism and the C-G and C-A haplotypes were associated with BMI and obesity, where GG was the risk genotype (P=0.033 for BMI; P=0.010 for obesity). CONCLUSION: These data suggest that variants in the IL6R gene are not only involved in the determination of BMI but also relevant for the determination of BMD. The IL6R gene may belong to the growing list of genes known to be involved in both phenotypes.

COL1A1, ESR1, VDR and TGFB1 polymorphisms and haplotypes in relation to BMD in Spanish postmenopausal women.

INTRODUCTION AND HYPOTHESIS: Genetic studies of osteoporosis have focused on analysing single polymorphisms in individual genes - with inconclusive results. An alternative approach may involve haplotypes and gene-gene interactions. The aim of the study was to test the association between the COL1A1, ESR1, VDR and TGFB1 polymorphisms or haplotypes and bone mineral density (BMD) in Spanish postmenopausal women. METHODS: Sixteen polymorphisms were analysed in 719 postmenopausal women. ANOVA, ANCOVA and Xi2 tests were used to perform the statistical analysis. RESULTS: COL1A1 -1997G > T (p=0.04) and TGFB1 Leu10Pro (p=0.02) were found to be associated with adjusted lumbar spine (LS) BMD. Interactions were observed between: the COL1A1 -1997 G/T and Sp1 polymorphisms (p < 0.01 for LS BMD) and the COL1A1 -1663 indelT and VDR ApaI polymorphisms (p < 0.01 for femoral neck (FN) BMD). The COL1A1 GDs and ESR1 LPX haplotypes were associated with FN BMD (p=0.03 and p=0.03). CONCLUSIONS: Polymorphisms at COL1A1 and TGFB1 and haplotypes at COL1A1 and ESR1 were found to be associated with BMD in a cohort of postmenopausal Spanish women. Moreover, COL1A1 polymorphisms showed significant interactions among them and with the VDR 3' polymorphisms.

Two successful pregnancies in pyridoxine-nonresponsive homocystinuria.

Two successful pregnancies are reported in a pyridoxine-nonresponsive woman who was also homozygous for the MTHFR 677C>T polymorphism. Two healthy children were delivered, although there had also been an early miscarriage of an apparently normal fetus in another pregnancy. Management of the patient's homocystine and methionine levels was maintained throughout pregnancy and, in view of the increased thromboembolic risk, anticoagulation therapy was also included in management.