To search for phenotypes use the Phenotypes option at the top of the screen.
In GWAS Central we have annotated all phenotypes to MeSH or HPO, which provides the ability to carry out powerful searches by entering search terms or by using a MeSH/HPO tree.

Entering a search term not only results in phenotypes annotated to that term (or a synonym of that term), but it will also return phenotypes annotated to more specific versions of that term. For example, searching for ‘Autoimmune diseases’ will return all such phenotypes including rheumatoid arthritis and type I diabetes. Currently, only a single term search can be performed at a time.

Using the tree search you can search different phenotype groups at the same time. Two trees are provided: MeSH and HPO. Selecting parent terms will additionally return all child terms. However, the tree search allows the researcher to be more selective over phenotypes returned.