Genetic risk factors for lumbar disc disease.

Lumbar disc disease (LDD) is a common musculoskeletal disease affecting about 5% of all individuals. It is characterized by lumbar disc herniation, which causes nerve root irritation, either mechanically or via inflammatory mediators, and results in radiating pain, known as sciatica. Numerous studies have been conducted to identify the causes and risk factors for LDD. Lifting heavy loads, torsional stress and motor vehicle driving are among the best-identified environmental risk factors. However, it has become evident recently from family and twin studies that genetic factors may also be important in LDD. This hypothesis was strengthened by the identification of two collagen IX alleles associated with sciatica and lumbar disc herniation. In addition, disc degeneration has been shown to be related to an aggrecan gene polymorphism, a vitamin D receptor and matrix metalloproteinase-3 gene alleles.