Family 15DG2154 presented with the lethal microcephaly-micromelia syndrome in multiple pregnancies, which was mapped to a severe splicing variant in DONSON, the same variant that when inherited in trans with milder variants results in a much milder Seckel syndrome as described previously [32] (a range of DONSON-related phenotypes has also been described [33]). Here, DONSON is linked to Seckel syndrome.