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20 Diseases You've Probably Never Heard Of

Lesch Nyhan Syndrome
This syndrome can cause finger biting.
This syndrome can cause finger biting.

This disease is caused by the absence or deficiency of an enzyme. Symptoms include impaired kidney function, joint pain and self-mutilating behaviors such as lip and finger biting and/or head-banging. Additional symptoms may include muscle weakness (hypotonia), uncontrolled muscle movements and neurological impairment. Other names for it include HGPRT or HPRT deficiency, or hypoxanthine-guanine phosphoribosyl transferase deficiency.

Read More About the Disease From NORD