This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Twenty-nail dystrophy is a condition that affects the nails of the fingers and toes. The nails become rough, thin, and brittle. They appear similar to sandpaper. It was once thought that all 20 nails will be affected, but any number of nails can become rough and brittle. This condition most commonly occurs in childhood, but it can occur at any age. The exact cause is often unknown, but sometimes appears with other skin conditions such as lichen planus, psoriasis and alopecia areata. In some people, the symptoms of twenty-nail dystrophy improve or disappear over time, but in other people they persist for a long time.
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