Mental health conditions

PRACTICE POINT

There are currently no specific high-risk gene variants Gene variants are small DNA sequence changes (ie additions, duplications, deletions, substitutions). These variants can have a range of effects: some may cause disease (pathogenic variant), while others do not cause disease but may modify an individual’s risk of disease (i.e may increase risk or provide a protective effect). The vast majority of gene variants are benign and do not result in disease but rather contribute to the differences between people. that are associated with mental health disorders that are useful for predictive testing Pre-symptomatic testing aims to determine whether a person will almost certainly develop a particular genetic condition at some point in the future when symptoms of the condition have not yet manifested (eg Huntington disease). Predictive testing aims to determine whether a person who has no signs or symptoms of a specific condition at the time of testing has a specific pathogenic variant that increases the likelihood they will later develop the condition. Predictive testing is often performed in relation to genetic conditions that are not evident at birth, but have their onset during adulthood, such as some cancers (eg BRCA 1 and 2 testing). Predictive genetic testing in familial cancer syndromes can only be conducted when the family-specific genetic variant is known. Hence, genetic testing must generally first be done on a family member affected with the specific condition. in clinical practice. There are some genetic conditions with increased rates of mental health conditions. An example is the 22q11.2 deletion syndrome where there is an approximately 25% chance of schizophrenia. Generally, there are other features present that indicate the mental health condition is part of genetic syndrome. In such instances referral to a clinical geneticist should be considered. 

Some companies that offer personal genomic testing may include polygenic risk scores for common mental health conditions such as depression.  The clinical utility of such tests remains uncertain.