Osteoarthritis (OA) is a degenerative joint disease that causes pain and stiffness and decreases mobility. While OA is not always hereditary, experts believe that there may be a genetic component that increases the risk of developing this condition.

Around 32.5 million adults in the United States have OA. Various factors contribute to individuals developing OA, including increasing age, obesity, joint injuries, and a person’s sex.

While genetics play a role in increasing the risk of someone developing OA, this condition is not hereditary.

This article explores how genetics contribute to OA and discusses other risk factors.

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There are over 100 different types of arthritis, and OA is one of the most common. OA is a degenerative joint disease that worsens over time. Currently, there is no cure for this condition.

When a person has OA, their cartilage breaks down. Cartilage is a protective, fibrous connective tissue that cushions the ends of bones and allows them to move easily over each other.

When cartilage begins to break down, the bones rub against one another. In addition, bony spurs, or osteophytes, might form as the bone attempts to heal itself.

People with OA may experience pain, stiffness, and swelling in the joints.

Autoimmune forms of arthritis, such as rheumatoid arthritis, result from the immune system attacking the body’s healthy tissue.

However, doctors usually consider OA a “wear and tear” disease, as it is more common in people over the age of 50 and is more likely to affect weight-bearing joints, such as the knees and hips. Injuries or genetic predisposition can also increase the risk of OA.

While OA is not always heredity, in some cases, a person can inherit an increased risk of developing this condition. Experts do not currently know how the predisposition of an increased risk of developing OA passes between family members.

Experts estimate that around 40–70% of OA cases have a genetic component, with a stronger link for the hip, hand, and spine. The hereditary forms of OA arise from mutations in genes that help form and maintain bone and cartilage. This type of OA may appear at a young age and rapidly progress.

There is not a single specific gene that increases the risk of developing OA. Multiple genes and other risk factors, such as obesity, injuries, and joint anatomy, also contribute to OA.

Research suggests that several groups of genes may increase the risk of developing OA, including:

  • Cartilage extracellular matrix structural genes: Variations in the COL2A1 genes may reduce the durability of cartilage against stress in the hip and joints.
  • Bone density genes: Variations in estrogen receptor genes may increase the risk of developing OA. Additionally, variations in vitamin D receptor genes may increase the risk of having hand and knee OA.
  • Chondrocyte cell signaling genes: Variations in the FRZB gene may lead to an increase in the risk of females developing OA.
  • Inflammatory cytokine genes: Variations in IL-1R1 genes may increase the risk of hand OA.

While scientists have identified different gene variations that may contribute to OA, they do not yet know precisely what part genetics play in developing this condition.

Additionally, people with certain genetic traits or inheritable conditions, such as Ehlers-Danlos syndrome (EDS), may have an increase in the risk of developing OA.

People with EDS have low collagen levels, which can reduce their ability to support muscles and joints. This can lead to unstable and hypermobile joints that may contribute to OA.

More research is necessary to understand the complex interplay between genetic factors and OA.

The cause of OA is wear and tear at the joints.

A range of factors can contribute to individuals developing OA:

  • Joint injury or overuse: Repetitive stress on joints, bending, or injury can increase the likelihood of someone developing OA in that joint.
  • Age: The risk of OA increases as people age.
  • Gender: Females are more likely to develop OA than males, particularly after age 50.
  • Obesity: Having extra weight stresses weight-bearing joints, especially in the knee and hip. Obesity could also have metabolic effects that influence OA risk.
  • Race: Certain Asian populations have a lower-than-average OA risk.

Typically, OA risk increases with age and appears most often in individuals over the age of 50. However, it can appear in younger individuals, particularly after a bone fracture or a cartilage or ligament tear.

OA usually worsens over time and can develop in several joints. It often begins in a single large joint, such as a hip or knee, but it may also involve a smaller joint, such as an ankle.

Some people may have OA in a single joint, but it may progress to involve other joints, such as the spine, neck, and wrists.

While doctors do not fully understand why this happens, it is possible that the pain from OA causes the individual to move differently, which then forces the joints out of alignment.

OA is a degenerative condition with no cure. This condition worsens over time and can cause significant difficulty in mobility.

If a person has individuals in their family with OA, it does not mean they will also develop the condition. Experts estimate that the heritability of OA is around:

  • 40% for the knee
  • 60% for the hip
  • 70% for the spine

Researchers do not fully understand the link between OA and life expectancy. In some cases, OA of the knee or hip may negatively affect an individual’s life expectancy, but this is potentially due to pain, difficulty in mobility, and other health conditions.

Other types of OA, such as OA of the hand, do not appear to have an effect on life expectancy.

OA is a degenerative joint disease that worsens over time, causing difficulty in mobility and pain. Age is the primary factor that increases OA risk, but other causes include injury, obesity, sex, and genetics.

The heritability of OA is around 40–70%. However, having family members with OA does not mean that a person will develop the condition.