Which test can distinguish among X-linked, autosomal, and X-linked carrier forms of CGD?

The dihydrorhodamine 123 test is specifically designed to assess the functionality of the NADPH oxidase complex in phagocytes, which is critical for the oxidative burst necessary for bacterial killing. In the context of chronic granulomatous disease (CGD), this test can provide insight into the underlying genetic nature of the disorder.

In CGD, mutations can occur in genes located on the X chromosome or in autosomal genes, leading to varying inheritance patterns. The dihydrorhodamine 123 test distinguishes between the different forms of CGD based on how effectively phagocytes produce reactive oxygen species (ROS). For instance, X-linked CGD (the most common form) typically shows a dramatic reduction in ROS production due to the absence of a functional component of the NADPH oxidase complex. Conversely, in autosomal recessive forms, there might still be some residual function depending on the specific gene mutation involved.

By analyzing the ROS production in phagocytes from a patient and comparing it to normal standards, clinicians can identify whether the defect is due to a specific autosomal mutation or an X-linked mutation. This allows for a clearer diagnosis of the form of CGD present, including identifying carriers in females who may have one normal and one