RESUMO
Spondyloepiphyseal dysplasia (SED), Omani type (OMIM 608637) is a recessively inherited skeletal dysplasia previously described in two distantly related families from the Republic of Oman. The phenotype consists of short stature, severe kyphoscoliosis, arthritic joints (elbows, wrists, knees), secondary large joint dislocations, rhizomelia, fusion of carpal bones and mild brachydactyly. Affected individuals were homozygous for a missense mutation, R304Q in CHST3 that encodes the enzyme chondroitin 6-O-sulfotransferase-1 (C6ST-1). This enzyme mediates the sulfation of proteoglycans, particularly chondroitin sulfate (CS), in the extracellular matrix of cartilage. Here we describe the identification of a mutation (857T > C predicting the substitution L286P) in CHST3 in a Turkish family and extend the clinical phenotype of SED-Omani type to include congenital joint dislocation, club feet, ventricular septal defect, deafness, metacarpal shortening and accessory carpal ossification centers. Fibroblasts and urine obtained from affected patients demonstrated negligible levels of 6-O-sulfated GalNAc residue in CS. Furthermore, the 6-O-sulfotransferase activity of cloned C6ST-1 into which the L286P mutation had been introduced was dramatically reduced, confirming the pathogenicity of this substitution. These results indicate that the clinical consequences of a deficiency of 6-O-sulfation in CS can be varied and that a clinical spectrum may exist similar to that seen in other skeletal dysplasias characterized by disorders of proteoglycan sulfation.
Assuntos
Osteocondrodisplasias/genética , Mutação Puntual , Sulfotransferases/genética , Substituição de Aminoácidos , Criança , Pré-Escolar , Clonagem Molecular , Consanguinidade , Dissacarídeos/urina , Feminino , Fibroblastos/enzimologia , Humanos , Omã , Osteocondrodisplasias/diagnóstico por imagem , Osteocondrodisplasias/enzimologia , Linhagem , Fenótipo , Radiografia , Coluna Vertebral/anormalidades , Coluna Vertebral/diagnóstico por imagem , Sulfotransferases/urina , Carboidrato SulfotransferasesRESUMO
We report two cases of apparently balanced complex de novo chromosomal rearrangements (BCCR) detected prenatally at 17 weeks and 10 weeks of gestation, respectively. Chromosomes were studied using GTG-banding and fluorescent in situ hybridization (FISH). In one case four chromosomes and in the other case three chromosomes were involved in the rearrangements. One of the pregnancies was terminated and no external or internal showed no abnormalities. The child is now 3 years old and has neither congenital anomalies nor evidence of delayed psychomotor development.