The investigators have named the condition PLCG2-associated antibody deficiency and immune dysregulation, or PLAID." Diagnosis
Diagnosis is typically obtained by an allergist or other licensed practitioner performing a cold test. During the cold test, a piece of ice is placed inside a thin plastic bag and held against the forearm, typically for 3–4 minutes. A positive result is a specific looking mark of raised red hives. The hives may be the shape of the ice, or it may radiate from the contact area of the ice. However, while these techniques assist in diagnosis, they do not provide information about temperature and stimulation time thresholds at which patients will start to develop symptoms, which is essential because it can establish disease severity and monitor the effectiveness of treatment. Management
Management largely consists of avoiding exposures that could trigger a reaction and taking medicine to manage the reaction. The best treatment for this allergy is avoiding exposure to cold temperatures. Avoiding triggers
Anything that lowers the skin temperature (not bodys core temperature) can trigger a reaction in affected people. Avoiding exposures limits the risk of a reaction. The reaction usually affects the body parts that are exposed, so cold air could trigger a reaction to exposed skin or in the breathing passages if cold air is inhaled. Risky exposures include:

Situations:
Cold weather, including snow: Exposure to cold or cool air can quickly trigger a reaction; for example walking by the open freezer cases in a supermarket. Air conditioning: Entering a cool building during a summer day can result in a reaction.
Cold urticaria (essentially meaning cold hives) is a disorder in large red welts called hives (urticaria) form on the skin after exposure to a cold stimulus. The hives are usually itchy and often the hands and feet will become itchy and swollen as well. Hives vary in size from about 7 mm in diameter to as big as about 27 mm or larger. This disorder, or perhaps two disorders with the same clinical manifestations, can be inherited (familial cold urticaria) or acquired (primary acquired cold urticaria). The acquired form is most likely to begin between ages 18 and 25, although it can occur as early as 5 years old in some cases. Life-threatening risks include suffocation resulting from swollen tissue (pharyngeal angioedema) induced by cold foods or beverages, drowning after shock from swimming in cold water, and anaphylactic shock. Types
Cold urticaria may be divided into the following types:

Primary cold contact urticaria
Primary cold contact urticaria is a cutaneous condition characterized by wheals, and occurs in rainy, windy weather, and after swimming in cold water and after contact with cold objects, including ice cubes. Secondary cold contact urticaria
Secondary cold contact urticaria is a cutaneous condition characterized by wheals, due to serum abnormalities such as cryoglobulinemia or cryofibrinogenemia are extremely rare, and are then associated with other manifestations such as Raynauds phenomenon or purpura. Reflex cold urticaria
Reflex cold urticaria is a cutaneous condition in which generalized cooling of the body induces widespread welting.