Background

Mutation in the membrane-bound transcription factor peptidase site 1 (MBTPS1) gene leads to a rare genetic skeletal disorder called Spondyloepiphyseal dysplasia, Kondo-Fu type (SEDKF). Currently, there are only 11 patients identified with this defect. This small number of patients is likely due to the fact that SEDKF patients have clinical features that overlap with type II collagenopathy patients leading to the SEDKF patients being misdiagnosed. Clinical presentations of patients with mutations in the MBTPS1 gene include spondyloepiphyseal dysplasia with associated kyphosis, dysmorphic facial features, retarded growth with skeletal abnormalities, decreased bone mineral density, and elevated plasma levels of lysosomal enzymes ().

The MBTPS1 gene encodes Site‑1 Protease (S1P), a key serine protease in the Golgi required for intracellular transportation