SFU studies causes behind sudden infant death

By Diane Mar-Nicolle

A team of researchers from Canada and the U.S. has found that a newly identified genetic variant can cause sudden cardiac arrest (SCA), which may explain certain cases of sudden unexpected death in infants (SUDI).

The research was conducted at Simon Fraser University under the supervision of biomedical physiology and kinesiology professor Glen Tibbits, who is also an investigator at BC Children’s Hospital.

“SUDI is a devastating occurrence for parents and health-care practitioners, particularly when post-mortem analysis is unable to pinpoint the cause of death,” Tibbits says.

“Thanks to post-mortem molecular genetic testing and innovative new technologies using induced pluripotent stem cells and genome editing, a significant number of SUDI cases can be attributed to SCA.”

The work stemmed from Sanam Shafaattalab’s PhD research and included contributions from fellow SFU researchers Alison Li, Eric Lin, Laura Dewar and Charlie Stevens. The team also received assistance from researchers at BC Children’s Hospital Research Institute, UBC, the University of Calgary and Ohio State University to develop the experimental platform used to assess genetic variants that could potentially be causal in sudden cardiac death of infants. (SCDI).

Using this platform, the team was able to introduce the TNNI1 R37C^+/- variant into human induced pluripotent stem cells (hiPSCs) and differentiate them into beating heart cells in the lab. Monitoring heart beat patterns under control conditions allowed the team to detect abnormal electrical activity or arrhythmias.

Tibbits explains that in people without the genetic variant, as one’s heart rate increases with exercise or stress, the period of electrical excitation shortens to accommodate the higher rates.  However, in people with this genetic variant, the shortened period of electrical excitation does not occur. Instead, Tibbits says that the mutation disrupts neonatal cardiac physiology by altering how calcium in the heart cells is handled.

“This can then trigger-life threatening arrhythmias in newborn’s hearts,” he adds.

Tibbits cautions there is still work to be done before this discovery can be used to develop a treatment.

“However, we will now inform the cardiologists and genetic counsellors who will work with families, parents, and siblings of the deceased infants to identify carriers of this variant and to develop a strategy to reduce SUDI within that community,” says Tibbits.  

The experimental platform developed by the team will also be useful in investigating other types of inherited arrhythmias induced by other genetic variants that might increase the risk for SCA.

The study was funded by the Stem Cell Network of Canada and CIHR and was published last week in the Proceedings of the National Academy of Sciences of the United States of America.