What is the primary characteristic of sickle cell disease?

Sickle cell disease is fundamentally characterized as a genetic disorder that results in the production of abnormal hemoglobin, known as hemoglobin S. In this condition, the red blood cells become rigid and crescent-shaped (or sickle-shaped), especially under low oxygen conditions. This distortion affects their ability to flow smoothly through blood vessels, leading to blockages, pain, and a variety of complications related to insufficient blood supply in different tissues.

This genetic aspect is crucial; sickle cell disease is inherited in an autosomal recessive manner, which means a person must inherit two copies of the mutated gene (one from each parent) to be affected by the disease. As a result, this malfunctioning hemoglobin contributes to a range of symptoms and complications, including anemia, frequent pain crises, increased risk of infections, and organ damage over time.

The other options describe conditions unrelated to the primary characteristic of sickle cell disease. A viral infection would not typically result in the characteristic red blood cell shape change, autoimmune diseases involve a different pathological mechanism where the immune system attacks the body's tissues, and clotting disorders pertain to issues with blood coagulation rather than the structural alteration of red blood cells.