, researchers have found.
Previous studies have found de novo genetic variants – those not found in either parent but which occur for the first time in their offspring – that increase the risk of cardiac and seizure disorders, but research on sudden unexplained deaths in children (SUDC) is limited, according to Matthew Halvorsen, PhD, of the University of North Carolina at Chapel Hill, and colleagues. Most cases of SUDC occur in children aged 1-4 years, and a lack of standardized investigation systems likely leads to misclassification of these deaths, they said.
Compared with sudden infant death syndrome (SIDS), which occurs in approximately 1,400 children in the United States each year, approximately 400 children aged 1 year and older die from SUDC annually. A major obstacle to studying these cases is that so-called molecular autopsies – which incorporate genetic analysis into the postmortem examination – typically do not assess the parents’ genetic information and thus limit the ability to identify de novo mutations, they added.
In a study published in the Proceedings of the National Academy of Sciences, Dr. Halvorsen’s group obtained whole exome sequence data from 124 “trios,” meaning a dead child and two living parents. They tested for excessive de novo mutations for different genes involved in conditions that included cardiac arrhythmias and epilepsy. The average age at the time of death for the children was 34.2 months; 54% were male, and 82% were White.
Children who died of SUDC were nearly 10 times as likely to have de novo mutations in genes associated with cardiac and seizure disorders as were unrelated healthy controls (odds ratio, 9.76). Most pathogenic variants were de novo, which highlights the importance of trio studies, the researchers noted.
The researchers identified 11 variants associated with increased risk of SUDC, 7 of which were de novo. Three of the 124 cases carried mutations (two for RYR2 and 1 for TNNI3) affecting genes in the CardiacEpilepsy dataset proposed by the American College of Medical Genetics and Genomics, strengthening the connection to seizure disorders.
Another notable finding was the identification of six de novo mutations involved in altering calcium-related regulation, which suggests a cardiac susceptibility to sudden death.
The data support “novel genetic causes of pediatric sudden deaths that could be discovered with larger cohorts,” the researchers noted. Taken together, they say, the gene mutations could play a role in approximately 9% of SUDC cases.
The study findings were limited by several factors, including lack of population-based case ascertainment, exclusive focus on unexplained deaths, potentially missed mutations, and use of DNA from blood as opposed to organs, the researchers noted.
However, they concluded, “the data indicate that deleterious de novo mutations are significant genetic risk factors for childhood sudden unexplained death, and that their identification may lead to medical intervention that ultimately saves lives.”
Findings highlight impact of SUDC
“This study is important because SUDC is a much more pressing medical need than most people realize,” said Richard Tsien, PhD, of New York University Langone Medical Center, and the corresponding author of the study.