Drivers of phenotypic variation in cartilage: Circadian clock genes.

Endogenous homeostasis and peripheral tissue metabolism are disrupted by irregular fluctuations in activation, movement, feeding and temperature, which can accelerate negative biological processes and lead to immune reactions, such as rheumatoid arthritis (RA) and osteoarthritis (OA). This review summarizes abnormal phenotypes in articular joint components such as cartilage, bone and the synovium, attributed to the deletion or overexpression of clock genes in cartilage or chondrocytes. Understanding the functional mechanisms of different genes, the differentiation of mouse phenotypes and the prevention of joint ageing and disease will facilitate future research.