Burgeoning interest in the genetics of schizophrenia and other major psychiatric disorders in the 1970s and 1980s led to several papers addressing the issue of genetic counselling for these conditions (1–13). Since then, we have gained appreciable knowledge, both in the field of genetic counselling and in the field of psychiatric genetics, which has helped to shape how genetic information about these psychiatric illnesses is conveyed to patients and families in the 21st century. In this paper, we review the genetic counselling process and use schizophrenia as an example to outline current knowledge about its genetics and issues arising in genetic counselling, including those pertaining to a genetic subtype of schizophrenia.

Manuscript received and accepted January 2001.
¹Doctoral Candidate, Genetics Department, Memorial University of Newfoundland, St John’s, Newfoundland.
²Genetic Counsellor, Schizophrenia Research Program, Queen Street Division, Centre for Addiction and Mental Health, Toronto, Ontario.
³Associate Professor, Department of Genetics and Department of Psychiatry, University of Medicine and Dentistry of New Jersey, Newark–Piscataway, New Jersey.
⁴Associate Professor, Department of Psychiatry, University of Toronto; Head, Genetics Section, Schizophrenia Research Program, Queen Street Division, Centre for Addiction and Mental Health, Toronto, Ontario.
Address for correspondence: Dr A Bassett, Schizophrenia Research Program, Queen Street Division, Centre for Addiction and Mental Health, 1001 Queen Street West, Toronto, ON  M6J 1H4
e-mail: anne.bassett@utoronto.ca

What is Genetic Counselling?

The term genetic counselling was coined by Sheldon Reed in the 1950s (14); it is a well-defined process that should ideally occur for any disorder wherein a significant risk to relatives is present (15). A formal definition of genetic counselling was established at the beginning of the 1970s by the American Society of Human Genetics (15) (Figure 1). This definition describes genetic counselling as a communication process that provides genetic information in a nondirective manner, facilitates decision making, and supports the individual seeking counselling (consultand) and the individual’s family.

Genetic counselling is traditionally provided for 1) mendelian disorders with a straightforward inheritance pattern (for example, dominant and recessive) of both pediatric and adult onset; 2) nonmendelian disorders of complex genetic etiology (for example, multifactorial) of both pediatric and adult onset; 3) genetic syndromes; 4) prenatal diagnosis of genetic conditions; and 5) teratogen assessment in pregnancy (16). Genetic counselling is provided by health-care professionals trained in genetics—primarily, by genetic counsellors (who are typically graduates from Master’s programs or equivalently trained nurses) and medical geneticists.