Chromatin profiling identifies chondrocyte-specific Sox9 enhancers important for skeletal development.

The transcription factor SRY-related HMG box 9 (Sox9) is essential for chondrogenesis. Mutations in and around SOX9 cause campomelic dysplasia (CD) characterized by skeletal malformations. Although the function of Sox9 in this context is well studied, the mechanisms that regulate Sox9 expression in chondrocytes remain to be elucidated. Here, we have used genome-wide profiling to identify 2 Sox9 enhancers located in a proximal breakpoint cluster responsible for CD. Enhancer activity of E308 (located 308 kb 5' upstream) and E160 (located 160 kb 5' upstream) correlated with Sox9 expression levels, and both enhancers showed a synergistic effect in vitro. While single deletions in mice had no apparent effect, simultaneous deletion of both E308 and E160 caused a dwarf phenotype, concomitant with a reduction of Sox9 expression in chondrocytes. Moreover, bone morphogenetic protein 2-dependent chondrocyte differentiation of limb bud mesenchymal cells was severely attenuated in E308/E160 deletion mice. Finally, we found that an open chromatin region upstream of the Sox9 gene was reorganized in the E308/E160 deletion mice to partially compensate for the loss of E308 and E160. In conclusion, our findings reveal a mechanism of Sox9 gene regulation in chondrocytes that might aid in our understanding of the pathophysiology of skeletal disorders.

Osteocondrodisplasia de tipo displasia campomélica / Osteochondrodysplasia of campomelic dysplasia type

La osteocondrodisplasia de tipo displasia campomélica es una alteración del desarrollo esquelético que se presenta de forma autosómica dominante. Se caracteriza por la angulación de las extremidades, junto con otras alteraciones, cardiopulmonares, orofaciales y neurológicas. Las mutaciones estudiadas presentes en el gen SOX9 son responsables de la mayoría de casos de estas alteraciones. Se presenta aquí un caso de displasia campomélica hijo de madre de 22 años con embarazo de 24 semanas.

Campomelic dysplasia (CD) is a type of osteochondrodysplasia or disorder of skeletal development with autosomal dominant inheritance. It is characterized by angulation of the limbs along with cardiopulmonary, orofacial and neurological alterations. Mutations involving the SOX9 gene are responsible for CD in most affected individuals. A case of CD is presented in a boy born at 24 weeks of gestational age to a 22-year-old mother.

Reporte de caso de síndrome FATCO: aplasia fibular, campomelia de tibia y oligosindactilia / A case report of a patient with FATCO syndrome: fibular aplasia, tibial campomelia and oligosyndactyly

El síndrome FATCO, por las siglas en inglés de aplasia fibular (Fibular Aplasia), campomelia de tibia (Tibial Campomelia) y oligosindactilia (Oligosyndactyly), es un conjunto de malformaciones óseas, en las que la alteración se centra en los huesos de la pierna. Es una entidad rara y hay pocos casos descritos en la Literatura internacional, y, hasta ahora, no se ha descrito ningún caso en Colombia. Presentamos aquí el caso de un recién nacido de sexo masculino con signos clínicos de manera prenatal y posnatal consistentes con síndrome FATCO sin otras malformaciones asociadas. Exponemos también una breve discusión sobre las diferentes malformaciones óseas y otros casos de FATCO en el mundo.

The FATCO syndrome, (Fibular Aplasia, Tibial Campomelia and Oligosyndactyly) are bone malformations with main alteration in lower limbs. It is a rare entity and there are few cases reported in international literature, and so far there are not published cases in Colombia. Here we present a case of a male newborn with prenatal and postnatal signs consistent with FATCO syndrome without other organs malformations, and there is a brief discussion about this syndrome and other different malformations associated with it.

Displasia esquelética campomélica: reporte de caso / Campomelic dysplasia: case report

La displasia campomélica es una osteocondrodisplasia poco frecuente, incluida dentro del grupo de las osteocondrodisplasias letales. Su origen genético son mutaciones en el gen SOX9 que se heredan de forma autosómica dominante. Se caracteriza clínicamente por la forma arqueada de las extremidades, malformaciones de la caja torácica, alteraciones cartilaginosas en el árbol traqueobronquial, alteraciones en la diferenciación genital y otras anomalías menores. Los pacientes con este diagnóstico no tienen un buen pronóstico, a pesar de instaurarse un manejo adecuado. Usualmente, la muerte se da en el período neonatal por insuficiencia respiratoria, debido a las malformaciones torácicas, aunque se describen casos con buen pronóstico. El diagnóstico temprano in utero, a través de la ecografía prenatal y la confirmación diagnóstica con radiografía convencional, son indispensables para un adecuado abordaje interdisciplinario del paciente. Se presenta el caso de un recién nacido masculino con displasia campomélica y su abordaje diagnóstico desde la radiología.

Campomelicdysplasia is a rare osteochondrodysplasia, which is included in the lethal osteochondrodysplasias group. Mutations in SOX9 gene are responsible for this disorder and its inheritance mechanism is autosomal dominant. Campomelicdysplasia is characterized by congenital bowing and angulations of long bones, tracheobronchial tree abnormalities, ambiguous genitalia, dislocated hips and other minor abnormalities. Prognosis is poor in spite of suitable management. Death is usually produced by respiratoryfailure due to thoracic malformations. The early in utero diagnosis through prenatal ultrasonography and its confirmation by conventional X–ray are both essential for an interdisciplinary management. We present a case of a male newborn with campomelicdysplasia and its radiological diagnostic approach.