Acquired Cold Urticaria- NOT a genetic form, this can be brought on by illnesses, bee
stings, underlying conditions etc.. You have a chance at growing out of this one,
and if it is caused by an underlying condition( like a thyroid disorder) will go away once the condition is treated. Always positive to an ice cube test, and can cause anaphylaxis. Has subtypes that fall under this
FCAS-Familial Cold Auto inflammatory Syndrome (also called FCAD) is a genetic type of CU. This
type is present at birth, and does not (according to Dr.'s) cause anaphylaxis. Instead it causes fevers, body aches and a general sick feeling for a day or more after exposure. Testing for FCAS is done through genetic testing. Also called Familial Cold Urticaria (FCU) or Familial Cold Auto inflammatory Disorder (FCAD).
FACU-Familial Atypical Cold Urticaria. This is another type of genetic CU, discovered about 3-4 years ago I believe.. This condition is not always present at birth, and can appear at anytime. It is also known to cause anaphylaxis. Testing is through a skin biopsy.
PLAID- This is the newest form of CU to be discovered, and can cause anaphylaxis. With this condition you also form
autoantibodies (antibodies that attack your own tissues and cells) giving you a bigger risk of an autoimmune disease and immune deficiency causing you to be sick more often, illness will affect you harder than others, and have a harder time
getting over the illness. Testing is done through genetic testing.
The Dr.'s that we have seen have said that history is so important when going to see a Dr. for a diagnosis. A lot of Dr.'s will rule out CU if the ice cube tests is negative, but they are finding that the genetic types are harder to get a
reaction from (even though they can still have a positive ice cube test), so CU can not and should not be ruled out due to a negative ice cube tests.
Again always check with your Dr. to see if this info pertains to you or your loved one.