Researchers have found that traditional genetic linkages may be poor predictors of autism or schizophrenia.
A team of researchers led by scientists at the University of Montreal have found that traditional genetic linkages may actually be poor predictors of mutations that predispose individuals to autism or schizophrenia. Their finding, that de novo gene mutations—cell DNA alterations—play a part in these conditions, could hold implications for disease prevalence and severity.
“This study emphasizes the importance of de novo mutations as genetic factors predisposing to autism and schizophrenia. We found an increased frequency of severe de novo mutations in critical brain genes in both of these diseases,” said senior author Guy Rouleau, professor, University of Montreal. “Harmful de novo mutations, as observed in this study, may in part explain the high global incidences of autism and schizophrenia.”
Because de novo mutations are the result of DNA replication errors that occur prior to cell division and are newly formed within each individual, the researchers were able to conclude that schizophrenia and autism may not be inherited from either parent.
Rouleau’s team also found that DNA obtained right from a patient’s blood was superior to blood obtained from patient-derived cell lines.
Lead author Philip Awadalla, professor of pediatrics, University of Montreal, added that the “source of biological material is crucial for these types of experiments. In the process of confirming our findings, we were also able to provide one of the first direct estimates of the human mutation rate. The number of mutations per generation is extremely small but on the order of what was previously indirectly inferred for human-chimpanzee comparisons. We also discovered that mutations can be introduced when cell lines are produced, which creates false-positive results. This artifact can significantly bias results and therefore great care needs to taken when analyzing these samples.”