While the variable phenotype of patients P1, P5 and P9–P11 are consistent with the clinical criteria for MBS6, 43, patient P12, who was identified as having a heterozygous nonsense mutation in REV3L, only had bilateral facial paralysis and no weakness of the abducens nerves, suggestive of the restricted HCFP phenotype (Fig. 1; Supplementary Table 5). The gene discussed is REV3L; the disease is Paralysis.