For example, Nijmegen breakage syndrome (NBS), exhibits microcephaly as well as distinct facial features including a small lower jaw, and is caused by apoptosis of neuroepithelial cells48 in association with hypomorphic mutations in NBS1. Similarly, specific mutations in MRE11 have also been shown to underlie craniofacial anomalies including a small jaw and chin, together with short palpebral fissures and microcephaly as part of the rare Ataxia Telangiectasia-like disorder49, 50, 51. Here, MRE11 is linked to microcephaly.