Arthralgia literally means pain and Polyarthralgia means pain in several joints, anything from two upwards. Polyarthralgia encompasses Simple Arthralgia in which the main symptom is pain with no clinical features of inflammation in the joints or morning stiffness, Osteoarthritis in which pain is usually in the large weight bearing joints such as the knees and hips and in the joints of the thumb and fingers, Seronegative Arthritis and Rheumatoid Arthritis. Each of these has a distinct clinical presentations and genetic basis.
Simple Arthralgia refers to arthritis with no clinical manifestation of inflammation. It is often associated with fever or infection. It is thought to be associated with HLA-B*27 or HLA-DRB1*04.
Osteoarthritis is the most common form of arthritis and is characterised by pain in the large weight bearing joints such as the knees and hips as well s in the joints of the thumb and fingers. Both genetic and environmental factors contribute to the predisposition to Osteoarthritis. Environmental factors include lifestyle factors such as being overweight, a sedentary occupation, repetitive use of joints and history of trauma to affected joints. Genetic factors include HLA-B*08, though the strong linkage disequilibrium on the HLA-A1, B8, DR17 haplotype makes it difficult to be certain.
Seronegative arthritis refers to arthritis without the presence of Rheumatoid factor. It typically affects multiple joints. It is thought to be associated with HLA-DRB1*04.
Rheumatoid Arthritis is a chronic inflammatory symmetrical arthritis (it affects both sides of the body equally) which affects multiple synovial lined joints. It is characterised by progressive articular damage leading to joint deformation and disability. Patients are Rheumatoid factor positive and up to 70% of patients develop autoimmunity to citrullinated protein. Rheumatoid Arthritis is associated with a set of shared epitopes at positions 70 – 74 in the genetic sequence of the HLA-DRB1 gene. These include the sequences QKRAA, QRRAA, RKRAA and RRRAA. HLA-DRB1 alleles which share these sequences include HLA-DRB1*01:01, HLA-DRB1*01:02, HLA-DRB1*04:01, HLA-DRB1*04:04, HLA-DRB1*04:05, HLA-DRB1*04:08, HLA-DRB1*10:01, HLA-DRB1*13:03, HLA-DRB1*14:02 and HLA-DRB1*14:06.
Genetic testing for Polyarthralgia is an aid to diagnosis rather than a strong diagnostic tool.
Do you or someone you know suffer from Polyarthralgia or are you a researcher working in this area? Please join the conversation. Leave a comment. Thanks.
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