Genetic counselling: its need in psychiatry and the directions it gives for future research.

The methods for investigating the extent to which genetic factors can influence vulnerability to psychiatric illness are, in increasing order of precision: family, twin, and adoption studies. The evidence from these studies is in support of a gene-environment interaction for schizophrenia and the affective disorders. While the family study method cannot supply precise etiological data, the empirically derived information can be used by the genetic counsellor to provide empirical risk estimates to the counsellee. The psychiatrist, geneticist, and social worker make an appropriate team for reliable genetic counselling. The clinician must determine the precise psychiatric diagnoses in family members which the geneticist may use to estimate risk. The social worker can follow-up the counselling session or sessions to assess the counsellees' understanding of what has been told to them. It is stressed that while genetic counselling should be available, clinical judgement should be exercised to ensure its appropriate use.