Postmortem genetic diagnosis of long QT syndrome in a case of sudden unexplained death of a young child: A case report and overview of regional guidelines for genetic testing

ABSTRACT: Many cases of sudden unexplained death in the young are due to heritable mutations that cause disturbances in cardiac conduction that cannot be diagnosed at the time of autopsy. Screening of immediate family members of the deceased can identify individuals affected with the same condition. The collection and freezing of unfixed tissue at autopsy is crucial for the genetic confirmation of heritable cardiac conduction disorders. The case of a young victim of sudden unexplained death demonstrates how electrocardiogram screening of relatives can identify a cardiac ion channel mutation in family members. Several North American guidelines address tissue retention in cases of sudden unexplained death of the young. Although similar guidelines have not been published for British Columbia, autopsies for most cases of unexplained death in infants and children under 16 years of age in BC are performed at BC Children’s Hospital, where a standard autopsy approach is used and tissue is snap-frozen. To ensure every family can obtain the care they need, regardless of the jurisdiction, physicians performing autopsies in cases of sudden unexplained death in the young should use standard autopsy practices and retain tissue suitable for future genetic testing. A death occurring instantaneous­ ly, or less than 24 hours after symptom onset, in an other­ wise healthy individual, without a known cause, is known as a “sudden unexplained death” (SUD), a defini­ tion recognized in ICD-10. Unex­ plained sudden cardiac death is a sub­ set of SUD, in which the cardiac cause of the death is not detectable by basic autopsy techniques such as gross and microscopic examination. In individ­ uals 1 year of age and older, such a death is referred to as “sudden unex­ plained death syndrome” (SUDS). Where no cause of death is identified after a thorough autopsy, scene inves­ tigation, and toxicological evaluation, Anna F. Lee, MDCM, PhD, FRCPC, Andrew D. Krahn, MD, FRCPC, FHRS, Shubhayan Sanatani, MD, FRCPC, Deborah E. McFadden, MD, FRCPC