Clubbing is a condition in which the ends of the fingers and toes swell and the nails bulge outward. The nails wrap around the fingers or toes and look raised, curved, and shiny.
Clubbing occurs more frequently in children born with heart defects and people with chronic heart, lung, liver, or thyroid disease. But simple hereditary clubbing can occur without heart or lung problems.
WebMD Medical Reference from Healthwise