In particular, heterozygous variants in the catalytic unit of RNA polymerase I, POLR1A, cause acrofacial dysostosis, Cincinnati type (MIM 616462), described in four unrelated patients exhibiting varying mandibulofacial dysostosis phenotypes, with or without extra-facial skeletal defects.3,4 As for the recessive disease, we previously reported two brothers, homozygous for POLR1A NM_015425.3:c.2801C>T, p.(Ser934Leu), with leukodystrophy and atrophy of cerebrum, cerebellum and corpus callosum, leading to spasticity and in the elder brother additionally neurological regression.5 The gene discussed is POLR1A; the disease is mandibulofacial dysostosis.