DNA-dependent RNA polymerases catalyze the synthesis of different types of RNA during transcription in eukaryotic cells. The protein encoded by POLR3A forms the largest subunit of the RNA polymerase III complex, which is mainly responsible for synthesizing several small RNAs like transfer RNA, ribosomal 5S-RNA and U6 RNA. Perturbations of the transcription machinery caused by POLR3A mutations have been associated with a specific form of leukodystrophy (4H syndrome)

International researchers have now determined specific biallelic POLR3A mutations in eight patients as the genetic cause of Wiedemann-Rautenstrauch syndrome and identified disturbed RNA polymerase III function as a novel mechanism for the development of progeroid disorders. Wiedemann-Rautenstrauch syndrome is a rare congenital disorder characterized by growth retardation, lipodystrophy, dental anomalies and facial dysmorphism. Already at birth, the affected children appear to be prematurely aged. The types of mutation identified in this study suggest that specific combinations of compound heterozygous variants of POLR3A must be present to cause the phenotype of Wiedemann-Rautenstrauch syndrome, including one variant that has a strong detrimental effect on protein function (splice-site or truncating mutation) and a variant exerting a milder functional effect (often a hypofunctional, intronic variant).

The results of the study have been published in the Journal of Medical Genetics.

Paolacci S, Li Y, Agolini E, … Hennekam RC. Specific combinations of biallelic POLR3A variants cause Wiedemann-Rautenstrauch syndrome. J Med Genet. 2018 Oct 15; Epub ahead of print