Next-generation sequencing is a powerful diagnostic tool, and even though it is still of limited use in clinical practice, genome sequencing will be increasingly applied. Transition to wider genetic screening methods as clinical exome or genome sequencing has the potential to detect more variants of unknown significance as well as secondary findings. It calls for close cooperation between the laboratory geneticist and the medical geneticist. Pre- and post-test genetic counselling must be offered systematically, and always when there is a high risk of finding germ line variants.