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Czech dysplasia OMIM 609162 is a recently established COL2A1 disorder characterized by normal height, earlyonset osteoarthritis, platyspondyly, short metatarsals, and the absence of ophthalmological complications or cleft palate. A specific missense mutation c.823C > T, R275C in the exon 13 of the COL2A1gene, coding for the triple helical domain of the alpha 1 chain of the type II collagen, has been linked to Czech dysplasia, which is quite a unique situation among the COL2A1 disorders. Since all of the 11 families and patients reported to date were of European ancestry, an ancient single origin of the R275C mutation was speculated about. Here we report on a Japanese family consisting of three patients with Czech dysplasia, each member showing valgus knees in addition to remarkably uniform manifestation of the clinical and radiological abnormalities. Mutation analysis documented the COL2A1c.823C > T mutation in all affected individuals. In conclusion, this report provides novel evidence for the independent occurrence of Czech dysplasia among the populations. © 2009 WileyLiss, Inc.

AbstractOsteopetrosis is a rare genetic disorder characterized by increased bone mineral density (BMD) due to osteoclast failure. T-cell immune regulator 1 (TCIRG1) plays crucial roles on osteoclast function, and its mutation causes autosomal recessive osteopetorosis. However, mutations in TCIRG1 have never been identified in autosomal dominant osteopetrosis (ADO). A 3-year-old boy was first presented to the clinic because of spontaneous radius and femur fractures. He has optic atrophy. The areal BMD at the lumbar spine was 1274 g/cm2(233% of normal). Laboratory tests revealed no remarkable abnormal findings, including anemia, except for extremely elevated serum tartrate-resistant acid phosphatase-5b (14,600 mU/dL). Radiographically, the skull base, pelvis, and vertebrae showed a focal sclerosis. Genetic analysis revealed a novel de novoheterozygous missense mutation (His242Arg). Taken together with the mutation, his mild clinical features were diagnosed as ADO. This case implies that TCIRG1 could become a genetic candidate for ADO in addition to malignant forms such as ARO.