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Progressive pseudorheumatoid dysplasia (PPRD) is a joint disease that worsens over time. This condition is characterized by breakdown (degeneration) of the cartilage between bones (articular cartilage). This cartilage covers and protects the ends of bones, and its degeneration leads to pain and stiffness in the joints and other features of PPRD.
PPRD usually begins in childhood, between ages 3 and 8. The first indications are usually an abnormal walking pattern, weakness and fatigue when active, and stiffness in the joints in the fingers and in the knees. Other signs and symptoms that develop over time include permanently bent fingers (camptodactyly), enlarged finger and knee joints (often mistaken as swelling), and a reduced amount of space between the bones at the hip and knee joints. Hip pain is a common problem by adolescence. Affected individuals have flattened bones in the spine (platyspondyly) that are abnormally shaped (beaked), which leads to an abnormal front-to-back curvature of the spine (kyphosis) and a short torso. At birth, people with PPRD are of normal length, but by adulthood, they are usually shorter than their peers. Affected adults also have abnormal deposits of calcium around the elbow, knee, and hip joints and limited movement in all joints, including those of the spine.
PPRD is often mistaken for another joint disorder that affects young people called juvenile rheumatoid arthritis. However, the joint problems in juvenile rheumatoid arthritis are associated with inflammation, while those in PPRD are not.
PPRD has been estimated to occur in approximately 1 per million people in the United Kingdom. The condition is thought to be more common in Turkey and the Middle East, although its prevalence in these regions is unknown. The condition in all regions is likely underdiagnosed because it is often misdiagnosed as juvenile rheumatoid arthritis.
PPRD is caused by mutations in the WISP3 gene. The function of the protein produced from this gene is not well understood, although it is thought to play a role in bone growth and cartilage maintenance. The WISP3 protein is made in cells called chondrocytes, which produce and maintain cartilage. This protein is associated with the production of certain proteins that make up cartilage, but its role in their production is unclear. WISP3 may also help control signaling pathways involved in the development of cartilage and bone and may help regulate the breakdown of cartilage components.
WISP3 gene mutations lead to an altered protein that may not function. Loss of WISP3 protein function likely disrupts normal cartilage maintenance and bone growth, leading to the cartilage degeneration and joint problems that occur in PPRD.
Changes in this gene are associated with progressive pseudorheumatoid dysplasia.
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
These resources address the diagnosis or management of progressive pseudorheumatoid dysplasia and may include treatment providers.
You might also find information on the diagnosis or management of progressive pseudorheumatoid dysplasia in Educational resources and Patient support.
General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook. Read more about genetic testing (http://ghr.nlm.nih.gov/handbook/testing), particularly the difference between clinical tests and research tests (http://ghr.nlm.nih.gov/handbook/testing/researchtesting).
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You may find the following resources about progressive pseudorheumatoid dysplasia helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
Ask the Genetic and Rare Diseases Information Center (https://rarediseases.info.nih.gov/gard).
arthritis ; autosomal ; autosomal recessive ; breakdown ; calcium ; camptodactyly ; cartilage ; cell ; dysplasia ; gene ; homeostasis ; inflammation ; inherited ; joint ; juvenile ; prevalence ; protein ; recessive
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
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