Genetic deficiency of tartrate-resistant acid phosphatase associated with skeletal dysplasia, cerebral calcifications and autoimmunity
Vertebral and metaphyseal dysplasia, spasticity with cerebral calcifications, and strong predisposition to autoimmune diseases are the hallmarks of the genetic disorder spondyloenchondrodysplasia. We mapped a locus in five consanguineous families to chromosome 19p13 and identified mutations in ACP5, which encodes tartrate-resistant phosphatase (TRAP), in 14 affected individuals and showed that these mutations abolish enzyme function in the serum and cells of affected individuals. Phosphorylated osteopontin, a protein involved in bone reabsorption and in immune regulation, accumulates in serum, urine and cells cultured from TRAP-deficient individuals. Case-derived dendritic cells exhibit an …
Recessive multiple epiphyseal dysplasia (rMED): phenotype delineation in eighteen homozygotes for DTDST mutation R279W.
Multiple epiphyseal dysplasia (MED) is a generalised skeletal dysplasia that although relatively mild is associated with significant morbidity. Joint pain, joint deformity, waddling gait, and short stature are the main clinical signs and symptoms. In the past, the disorder was subdivided into the milder Ribbing type, usually with flattened epiphyses,1 and the more severe Fairbank type with round epiphyses,2 but many cases were not classifiable as clearly either type.3 MED can be caused by mutations in at least six separate genes: COMP ,4–7 collagen IX ( COL9A1 , COL9A2 , and COL9A3 ),8–13 matrilin 3 ( MATN3 ),15 and the sulphate transporter, DTDST ( DTDST/SLC26A2 ). We have previously repor…
Preselection of cases through expert clinical and radiological review significantly increases mutation detection rate in multiple epiphyseal dysplasia
Skeletal dysplasias are difficult to diagnose for the nonexpert. In a previous study of patients with multiple epiphyseal dysplasia (MED), we identified cartilage oligomeric matrix protein (COMP) mutations in only 36% of cases and suspected that the low-mutation detection rate was partially due to misdiagnosis. We therefore instituted a clinical–radiographic review system, whereby all cases were evaluated by a panel of skeletal dysplasia experts (European Skeletal Dysplasia Network). Only those patients in whom the diagnosis of MED was confirmed by the panel were screened for mutations. Under this regimen the mutation detection rate increased to 81%. When clinical–radiological diagnostic cr…