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Spontaneous germline mutations generate genetic diversity in populations of sexually reproductive organisms, and are thus regarded as a driving force of evolution. However, the cause and mechanism remain unclear. 8-oxoguanine (8-oxoG) is a candidate molecule that causes germline mutations, because it makes DNA more prone to mutation and is constantly generated by reactive oxygen species in vivo. We show here that endogenous 8-oxoG caused de novo spontaneous and heritable G to T mutations in mice, which occurred at different stages in the germ cell lineage and were distributed throughout the chromosomes. Using exome analyses covering 40.9 Mb of mouse transcribed regions, we found increased frequencies of G to T mutations at a rate of 2×10-7 mutations/base/generation in offspring of Mth1/Ogg1/Mutyh triple knockout (TOY-KO) mice, which accumulate 8-oxoG in the nuclear DNA of gonadal cells. The roles of MTH1, OGG1, and MUTYH are specific for the prevention of 8-oxoG-induced mutation, and 99% of the mutations observed in TOY-KO mice were G to T transversions caused by 8-oxoG; therefore, we concluded that 8-oxoG is a causative molecule for spontaneous and inheritable mutations of the germ lineage cells. [ABSTRACT FROM AUTHOR]

Abstract Case report  Bursal cysts (bursitis) are attributed to repeated microtrauma of the connective tissue around the synovial joint and are rare in the coccygeal region. Materials and methods  A 10-year-old boy had a subcutaneous tumor at the midline of the buttock. He could not walk and slid himself in a seated position because of psychomotor retardation. MR images showed a cystic lesion overlying the coccygeal bone, the intensity of which was identical to cerebrospinal fluid (CSF). Although meningocele was suspected, constructive interference in steady-state (CISS) MR images clearly depicted a discontinuity between the cyst and CSF space. Results and conclusion  It was conceivable that repeated friction between the coccygeal bone, which projected posteriorly, and overlying subcutaneous tissue during movement resulted in the formation of a bursal cyst. In addition to total removal of the cyst, the coccygeal bone was planed away to prevent friction. We should keep this rare clinical entity in mind in cases that appear to be sacrococcygeal meningocele. [ABSTRACT FROM AUTHOR]