Perinatal death, of a fetus or newborn, is a devastating event for families. Following nationwide multicentre recruitment, we assessed ‘genomic autopsy’ as an adjunct to standard autopsy for 200 families who experienced perinatal death, and provided a definite or candidate genetic diagnosis in 105 families. From this understudied cohort, half of the (candidate) diagnoses were phenotype expansions or novel disease genes, revealing previously unknown in-utero presentations of existing developmental disorders, and genomic disorders that are likely incompatible with life. Among the definite diagnoses, 43% were recessively or dominantly inherited, posing a 25% or 50% recurrence risk for future pregnancies. Ten families used their diagnosis for preimplantation or prenatal diagnosis of 12 pregnancies, facilitating the delivery of ten healthy newborns and management of two affected pregnancies. We emphasize the clinical importance of genomic investigations of perinatal death, with short turn-around times, enabling accurate counselling and options for families to prevent recurrence.
