Is Arthritis Hereditary?

Answering a question like, "Is arthritis hereditary?" is never simple. For a start, there are more than 100 types of arthritis, from septic arthritis to ankylosing spondylitis. For some, the answer is a definitive no; others are more complicated.

It's also challenging to say the degree to which arthritis is caused by genetics. Though we've discovered certain genes that are definitely associated with specific types of arthritis, simply having these genes doesn't guarantee that arthritis occurs – dietary and lifestyle factors are also critical.

Below we'll go through the four most common types of arthritis affecting the feet, answering if arthritis is hereditary for each. We'll also identify other risk factors you should consider.

Is arthritis hereditary?

Osteoarthritis

Osteoarthritis (OA) is the most common type of arthritis, affecting more than 32.5 million adults in the US. Sometimes referred to as "wear-and-tear" arthritis, it's caused by the breakdown of the cartilage covering the bone ends. When these bone ends rub, patients complain of pain, tenderness, stiffness, and inflammation.

Given this, you may imagine OA isn't hereditary. However, genetic mutations can alter your cartilage, increasing or decreasing your risk. In fact, it's estimated that between 40% to 65% of OA has a genetic component – rising in hand and hip cases. 

Nevertheless, no single gene causes the condition. So, even if your family suffers from OA, there's no guarantee you will too. 

Rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune condition. That means the immune system mistakes healthy joint tissues for an invading pathogen. As it attacks the tissue, it breaks down the joint, causing inflammation, pain, low-grade fever, fatigue, and loss of appetite. If left untreated, RA will eventually cause the complete degradation of a joint. 

It's estimated that the heritability of RA is as much as 60% - with 37% specifically associated with the human leukocyte antigen (HLA) system (genes that modulate your immune response). 

Research has identified several other genes that may be involved, including:

• PTPN22 is linked with RA development and progression

• STAT4 regulates and activates the immune response

• TRAF1, C5 are associated with chronic inflammation

Inheriting these genes does not "cause" RA, but it does increase the risk RA will occur. So, RA is not 100% hereditary but has a significant genetic component.

Psoriatic arthritis

As the name suggests, psoriatic arthritis (PsA) is associated with the skin condition psoriasis. Like RA, psoriatic arthritis is an inflammatory condition that causes pain and swelling in one or more joints. Common symptoms include morning stiffness, "sausage-like" fingers and tones, pitted nails, fatigue, and silvery-white patches on the skin (classic psoriasis).

Not everyone who suffers from psoriasis will notice arthritis, nor do all patients with PsA have the characteristic scaly, white plaques. Certain genetic differences, psoriasis with nail involvement, and immune system problems all increase the risk of PsA. Lifestyle risk factors include smoking, obesity, high-stress levels, excess alcohol consumption, infections, certain medications, and a diet high in saturated fats.

Genetically, PsA is linked to variations in the HLA complex (like RA), although other genes are believed to play small roles in its development. Despite these genetic links, the patterns for inheritability are notoriously unpredictable. Still, around 40% of people with PsA have at least one close family member with either PsA or psoriasis. 

Gout

Gout is a type of inflammatory arthritis caused by high uric acid levels in the blood; it is not an autoimmune disease. Uric acid is produced by the breakdown of purines found in certain foods. When uric acid levels rise, the risk of urate crystals forming in the joints increases. These needle-sharp crystals inflame the surrounding tissues causing arthritis.

There are three primary causes of high uric acid levels: (1) increased purine consumption, (2) increased breakdown of purines, or (3) decreased excretion of uric acid. 

The first cause is entirely dietary and not genetic. However, certain genes, like SLC2A9 and ABCG2, are associated with the excretion of uric acid via the kidneys and gut. When these genetic influences are combined, the heritability of gout is estimated at 65%, and 20% of people with gout have a relative with the condition, particularly a sibling or parent.

Other risk factors for gout are being male between the ages of 30 and 50, obesity, certain medications (like diuretics), alcohol consumption, poor kidney function, a purine-rich diet, and a high fructose diet.

Final thoughts

Genetics plays a role in most common types of arthritis. However, simply having a genetic predisposition to these conditions is by no means a guarantee that arthritis will develop. Still, if you have a family member with arthritis, it may be worth minimizing the other risk factors. That could mean losing weight, quitting smoking, eating a healthy and balanced diet, and increasing your weekly exercise.