| Characteristic | Summary |
|---|---|
| Disease Name | Osteogenesis Imperfecta Type IX (pqac-00000001, pqac-00000002) |
| OMIM ID | 259440 (pqac-00000001, pqac-00000005) |
| Gene | **PPIB** (peptidyl-prolyl cis-trans isomerase B) (pqac-00000001, pqac-00000003) |
| Protein | Cyclophilin B (CyPB), an ER-resident peptidyl-prolyl cis-trans isomerase and collagen chaperone (pqac-00000001, pqac-00000002) |
| Chromosome | 15q22.31 *(reported genomic locus for **PPIB**; chromosome location not explicitly stated in retrieved context)* (pqac-00000003) |
| Inheritance | Autosomal recessive (pqac-00000001, pqac-00000044) |
| Severity Range | Moderate to perinatal lethal; reported phenotypes span moderate OI to severe/perinatal lethal disease (pqac-00000002, pqac-00000036) |
| Key Clinical Features | Bone fragility, multiple fractures, short stature/growth deficiency, bowed long bones, scoliosis/kyphosis, gray sclerae, joint hypermobility, absence of rhizomelia, and no dentinogenesis imperfecta reported in at least one patient (pqac-00000008, pqac-00000012, pqac-00000013) |
| Molecular Mechanism | Impaired procollagen prolyl 3-hydroxylation, delayed collagen folding/chain association, abnormal post-translational modification and cross-linking, intracellular retention of overmodified collagen with ER stress/cellular stress (pqac-00000019, pqac-00000020, pqac-00000036) |
| Prevalence | Ultra-rare; literature in retrieved context includes the first 2 families (2009) and 3 additional families (2011), consistent with **<10 families reported** in early literature (pqac-00000043, pqac-00000044) |
| Animal Models | **Ppib−/−** mice recapitulate OI with kyphosis, osteoporosis, reduced BMD/BV/TV, abnormal collagen fibrils, increased brittleness, and reduced bone strength (pqac-00000026, pqac-00000028, pqac-00000030) |
| Treatment | Supportive multidisciplinary care; bisphosphonates are standard for moderate/severe OI, and intravenous pamidronate was used in reported PPIB-mutant patients; orthopedic surgery, physiotherapy, and rehabilitation are important adjuncts (pqac-00000008, pqac-00000041, pqac-00000047, pqac-00000049) |


*Table: This table summarizes the core disease characteristics of Osteogenesis Imperfecta Type IX, including genetics, clinical presentation, mechanism, rarity, model systems, and current management. It is useful as a compact knowledge-base style overview anchored to cited evidence from the retrieved literature.*