Contributions of genetic studies to clinical psychiatry.

Recent twin and family studies have demonstrated a genetic factor in Gilles de la Tourette syndrome, some cases of infantile autism, enuresis, specific reading disability, sleepwalking, night terrors, common fears and anxiety. Family studies have been used to elucidate the nosological relationship of psychiatric disorders; e.g. anorexia nervosa (to affective disorder), Gilles de la Tourette syndrome, and sleeptalking. Advances in biochemical genetics and in enzyme polymorphisms suggest that there are wide individual variations in the adverse effects of drugs and that dosage should be tailored to the individual patient. Recently molecular genetic methods have been introduced to psychiatry, but a major breakthrough in this field appears to be still years away.