TORONTO, May 12, 2022 – Researchers at The Hospital for Sick Children (SickKids) and Centre for Addiction and Mental Health (CAMH) have found that repeated DNA sequences in the genome may contribute to an individual’s risk of developing schizophrenia.
Tandem repeats are a class of DNA sequence where two or more nucleotides, known as the building blocks of DNA, are repeated adjacent to one another. Sometimes these repeats can expand when they are passed from one generation to the next. As a repeat sequence expands, the likelihood that it may disrupt a gene’s function increases.
Tandem repeat expansions are known to contribute to more than 50 conditions, including Huntington’s Disease. Less is known about the role of these tandem repeats in a complex disorder like schizophrenia, which is influenced by the effects of many variants in different genes.
Led by Dr. Ryan Yuen, Scientist in the Genetics & Genome Biology program at SickKids, and Dr. Anne Bassett, a Senior Scientist at CAMH and University Health Network, a study published May 12, 2022 in Molecular Psychiatry found that individuals with schizophrenia have a high number of rare tandem repeat expansions that are not typically found in the general population. These tandem repeat expansions are located near genes, and often together with other genetic variants, that are known to be associated with schizophrenia.
As part of the study, the team found that the expansions were also present in the sequenced genomes of individuals with a family history of schizophrenia.
“This is the first time these rare repeat expansions have been assessed genome-wide in schizophrenia. Our findings suggest that the tandem repeat expansions are an important class of variants that contribute to schizophrenia risk,” says Yuen.