2. Clubbed Nails
This condition is characterized by enlarged fingertips with nails that curve right around the edge. The U.S. Library of Medicine says there are some disorders of varying seriousness that clubbed nails may be characteristic of.
Some of the less-serious problems associated with nail clubbing are Celiac disease (a gluten allergy), an overactive thyroid, or dysentery (severe diarrhea with pain). However, the most common ailment associated with clubbed nails is lung cancer. It can also be caused by heart defects and lung disorders, such as Cystic Fibrosis.