Which disorder is characterized by a defect in heme synthesis?

Porphyria is indeed characterized by a defect in heme synthesis. This group of disorders results from a deficiency of one of the enzymes involved in the biochemical pathway that produces heme, the iron-containing compound in hemoglobin that is crucial for oxygen transport in the blood. When there is an enzyme deficiency, it leads to a buildup of porphyrins or their precursors, which can manifest clinically in various ways, including skin sensitivity, abdominal pain, and neuropsychiatric symptoms.

Understanding heme synthesis is pivotal in recognizing the underlying issues in porphyrias, as these deficiencies can significantly disrupt the normal production of heme, leading to both acute and chronic symptoms depending on which enzyme is affected. This highlights the importance of proper heme production for overall cellular function and health.