The and Riley-Day syndromes are two of several syndromes associated with self-injurious behavior. Lesch-Nyhan syndrome is caused by a deficiency in the enzyme hypoxanthine guanine phosphoribosyltransferase. The lack of this enzyme is associated with mental retardation and severe self-biting, particularly of the lips, tongue, and fingers.24 The exact mechanisms causing the self-mutilation are poorly understood. Hypotheses range from a problem with pain perception25 to a dynamic interplay between dopamine uptake, serotonin, and the neuronal systems of the basal ganglia.26
Riley-Day syndrome is a disorder of the autonomic nervous system with an autosomal recessive mode of inheritance.27,28 The diagnosis is based on clinical features that include
The disease probably results from an as-yet unidentified enzymatic insufficiency.
Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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