[Complex hereditary diseases with psychiatric symptoms].

Family and adoption studies indicate that genetic factors play a role in the development of many psychiatric disorders. A variable number of possible interacting genes giving a predisposition to the diseases is likely. The genetic dissection has been hampered by genetic complexity as well as by difficulties in defining the phenotypes. Genetic mapping efforts using sib pairs, twins and individual large families have revealed preliminary or tentative evidence of susceptibility loci for a number of psychiatric disorders. Illnesses described in this article include the prion disease familial fatal insomnia (FFI), alcoholism, anorexia nervosa, autism, bipolar affective disorder, dyslexia, enuresis nocturna, epilepsia, obsessive-compulsive disorders (OCD), schizophrenia, and the dementias, Alzheimer's disease and frontal lobe dementia. The genes and proteins related to the newly discovered transmitter in the central nervous system, nitric oxide (NO), and its genes and proteins are also reviewed. The number of mapped human genes now exceeds 30,000 of the estimated total number of 60,000 to 100,000 genes. This rapid development will facilitate gene mapping and efforts to isolate and identify the genes responsible for symptom susceptibility in many of the aetiologically unclear psychiatric diseases with complex genetic origin.