When the 6q terminal deletion extends to 7.1 Mb, the majority of the patient’s clinical features can be attributed to the DLL1. Deletions exceeding 7.1 Mb result in a more severe phenotype, such as such as abnormality of the anus, either anal atresia or an ectopic anus (Engwerda et al., 2023). Here, DLL1 is linked to imperforate anus.