Which of the following is NOT considered a collagen disorder?

Collagen disorders primarily involve abnormalities in the structure, production, or function of collagen, a key structural protein found throughout the body, particularly in connective tissues. Ehlers-Danlos syndrome is a classic example of a collagen disorder, characterized by hypermobility, skin elasticity, and a tendency for easy bruising due to defects in collagen synthesis.

Rheumatoid arthritis and systemic lupus erythematosus (SLE) are autoimmune conditions that can impact connective tissues and may involve collagen but are not classified as primary collagen disorders. While they may affect the joints and skin, their primary pathophysiology relates to immune dysregulation rather than a direct defect in collagen itself.

Ulcerative colitis is primarily an inflammatory condition affecting the gastrointestinal tract, particularly the colon, and does not primarily involve collagen or its synthesis. It is characterized by inflammation and ulceration of the colonic mucosa. Therefore, it does not fall into the category of collagen disorders as it does not involve the fundamental structural abnormalities associated with connective tissues and collagen.

This makes ulcerative colitis the option that is not considered a collagen disorder.