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BackgroundIt has been suggested that the accumulation of damage to mitochondrial DNA is a major cause of age related, degenerative disease. Aging is known to cause bone loss leading to a fall in bone mineral density and disruption of bone microarchitecture. However, despite the evidence of age related bone loss, no attempt has been made to detect specific deletions of mitochondrial DNA in the bone of aged individuals.AimsTo detect bone specific, age related deletions in mitochondrial DNA.MethodBlood leucocytes and bone biopsies from patients who had undergone orthopaedic surgery were used as a source of mitochondrial DNA and screened for deletions using the polymerase chain reaction.ResultsAlthough no deletions were detected in the blood mitochondrial DNA, specific deletions in bone mitochondrial DNA were found in three of five elderly subjects.ConclusionThe findings of this study suggest that there could be a link between mitochondrial DNA deletions and free radical induced apoptosis of bone cells in the development of age related bone loss.

AimTo examine the possible influence of the MHC class II antigens alleles in the formation of the multinucleate aggressive giant cell tumour of bone.MethodsHLA class II antigen alleles were investigated in eight white patients from north east England with confirmed diagnosis of giant cell tumour of bone. All had locally aggressive, immunophenotypically HLA-DR negative giant cell tumours.ResultsFive of the eight patients were found to be positive for HLA-DRB1^*0801/3, the distribution of this allele in healthy white controls being quite low (2%). All but one of the patients possessing DRB1*080 also expressed DRB1*070.ConclusionsHLA-DRB1*080 is predominant in patients with immunophenotypic HLA-DR negative giant cell tumour of bone; individuals with the genotype 070/080 are at particularly high risk of developing giant cell tumour of bone.