A novel splicing mutation in FKBP10 causing osteogenesis imperfecta with a possible mineralization defect

Osteogenesis imperfecta (OI) is a group of hereditary disorders characterized by bone fragility and osteopenia, with a broad spectrum of clinical severity. The majority of cases are dominantly inherited and due to mutations in type I collagen genes, whereas recessive forms are less frequent and attributable to mutations in different genes involved in collagen I post translational modifications and folding (prolyl-3-hydroxylase complex, SERPINH1, FKBP10). We report the case of a patient with an initially mild and then progressively severe form of osteogenesis imperfecta due to a novel homozygous splicing mutation in FKBP10 (intron 8 c.1399+1G>A), which results in aberrant mRNA processing and consequent lack of FKBP65 chaperone. Although this mutation does not affect collagen type I post translational modifications in dermal fibroblasts, the histomorphometric pattern of our patient's bone sample showed a mineralization defect possibly due to the mutation in FKBP10.