FCER1A encodes the alpha subunit of the high-affinity IgE receptor (FcεRI), which is primarily expressed on mast cells and basophils. This receptor plays a critical role in allergic responses by binding to the Fc region of immunoglobulin E (IgE). Cross-linking of IgE-bound FcεRI by allergens triggers cell degranulation and release of inflammatory mediators such as histamine and cytokines. The FCER1A gene is located on chromosome 1q23.3, and genetic variations in this gene have been associated with atopic conditions, including asthma, eczema, and food allergies.