Congratulations to the authors for this very nice paper.
Studies like this is much needed in order to gain more knowledge within this field - both to understand the true burden of SCD in the young and on how to use genetic testing in unexplained SCD in the future.
I am curious if you have any data on non-autopsied cases of sudden death, i.e. how high is your autopsy ratio in sudden death cases, and why were some cases autopsied, and not others? Your data provides incidence rates that are somewhat lower than we have seen in Denmark (with an autopsy rate of 75%, Winkel et al, EHJ 2011), and the proportion of males are slightly higher than in many other studies (72% vs 66%, although I am not sure it would reach statistic significance).
Another question: what was the reason why DNA in this prospective setting was not available in one-fifth of unexplained cases (where next-of-kin had given permission)? The question of course have some relevance in order to generalize the potential yield from genetic testing in these cases.