There is much talk nowadays about the Obamas getting a dog, and bless their hearts for preferring to adopt instead of purchasing. Let's say it again : purchasing from pet stores only helps the puppy mill business. Avoid it like the plague, and adopt from a shelter. Adopting saves lives---one, the dog you adopted; two, the dog who will take its place. Hypoallergenic means that something does not produce, or produces less allergic reactions in a certain person. Hypoallergenic dogs are not allergen-free. They just produce less irritating allergens than other dogs. The culprit is usually a protein found in saliva and dander, and this protein comes from the sebaceous glands.
Hypoallergenic dogs can be found in shelters. It is not true that all shelter dogs cause allergic reactions in people. It is not true that one has to go to breeders or pet stores to get a hypoallergenic dog.
As in other matters relating to adopting a pet, one has to deal with the particular dog or cat to see if it is a good match or not. Remember, it isn't all about the pet. The other variable in this experiment is the person himself, and his/her particular allergenic reactions. A dog that caused an allergic reaction in one person might not cause a reaction in another. If a dog caused allergic reactions in several people, then the dog requires a human who isn't prone to allergic reactions. As they say in shoe stores, try them on for size.