Chediak-Higashi syndrome is due to a defect in which cellular structure?

• A. Microtubules
• B. Actin filaments
• C. Lysosomes
• D. Golgi apparatus

Answer: (A)

Chediak-Higashi syndrome reflects a defect in lysosome-related organelle biogenesis and trafficking. The mutation disrupts the lysosome trafficking regulator, leading to abnormally large lysosomes that accumulate in various cells such as neutrophils, macrophages, platelets, and melanocytes. This abnormal lysosomal compartment impairs phagosome-lysosome fusion, reducing intracellular killing of bacteria, and it also affects melanosome maturation, causing oculocutaneous albinism. In immune cells, the problem extends to lysosome-like lytic granules required for NK cell and cytotoxic T cell function, contributing to immunodeficiency. While microtubules and actin filaments serve as tracks for moving these organelles, the central defect is in the lysosome system itself, not the cytoskeletal structures.