Trichotillomania often occurs with a number of other psychological conditions including anxiety, depression, obsessive-compulsive disorder or Tourette syndrome.

An estimated 3-5 percent of the US population are afflicted with the impulse-control disorder.

Those affected typically pull their hair out until they are bald in places.

The researchers observed a connection between trichotillomania and mutations in the SLITKR1 gene. Their findings are published in Molecular Psychiatry.