A rare cause of sudden unexpected death syndrome (SUDS) in the first year of life: endomyocardial fibroelastosis (EFE) due to two compound heterozygous MYBPC3 mutations.

Background: Autopsies regularly aim to clarify the cause of death; however, relatives may directly benefit from autopsy results in the setting of heritable traits ("mortui vivos docent").

Case Presentation: A case of a sudden unexpected cardiac death of a 5.5-months-old child is presented. Autopsy and thorough postmortem cardiac examinations revealed a massively enlarged heart with endomyocardial fibroelastosis. Postmortem molecular testing (molecular autopsy) revealed an unusual combination of two biparental MYBPC3 gene mutations likely to underlie the cardiac abnormalities. Thus, the molecular autoptic findings also had consequences for the relatives of the deceased child and impact on further family planning.

Conclusions: The presented case highlights the need for clinical autopsies including cardiac examinations and postmortem molecular testing; it also paves the way for further cascade screening of family members for cardiac disease, if a distinct genetic disorder is suspected.