A homozygous variant in mitochondrial RNase P subunit PRORP is associated with Perrault syndrome characterized by hearing loss and primary ovarian insufficiency
Authors: Hochberg Irit , Demain Leigh A. M. , Urquhart Jill E. , Amberger Albert , Deutschmann Andrea J. , Demetz Sandra , Thompson Kyle , O'sullivan James , Belyantseva Inna A. , Barzik Melanie , Williams Simon G. , Bhaskar Sanjeev S. , Jenkinson Emma M. , AlSheqaih Nada , Blumenfeld Zeev , Yalonetsky Sergey , Oerum Stephanie , Rossmanith Walter , Yue Wyatt W. , Zschocke Johannes , Taylor Robert W. , Friedman Thomas B. , Munro Kevin J. , O'Keefe Raymond T. , Newman William G. 
Published: July 2017

Perrault syndrome is a rare autosomal recessive condition characterised by sensorineural hearing loss in both sexes and primary ovarian insufficiency in 46 XX, females. It is genetically heterogeneous with biallelic variants in six genes identified to date (HSD17B4,HARS2,LARS2,CLPP,C10orf2andERAL1). Most genes possessing variants associated with Perrault syndrome are involved in mitochondrial translation. We describe a consanguineous family with three affected individuals homozygous for a novel missense variant c.1454C>T; p.(Ala485Val) inKIAA0391, encoding proteinaceous RNase P (PRORP), the metallonuclease subunit of the mitochondrial RNase P complex, responsible for the 5’-end processing of mitochondrial precursor tRNAs. In RNase P activity assays, RNase P complexes containing the PRORP disease variant produced ~35-45% less 5’-processed tRNA than wild type PRORP. Consistently, the accumulation of unprocessed polycistronic mitochondrial transcripts was observed in patient dermal fibroblasts, leading to an observable loss of steady-state levels of mitochondrial oxidative phosphorylation components. Expression of wild typeKIAA0391in patient fibroblasts rescued tRNA processing. Immunohistochemistry analyses of the auditory sensory epithelium from postnatal and adult mouse inner ear showed a high level of PRORP in the efferent synapses and nerve fibres of hair cells, indicating a possible mechanism for the sensorineural hearing loss observed in affected individuals. We have identified a variant in an additional gene associated with Perrault syndrome. With the identification of this disease-causing variant inKIAA0391, reduced function of each of the three subunits of mitochondrial RNase P have now been associated with distinct clinical presentations.

Author Summary

Perrault syndrome is a rare genetic condition which results in hearing loss in both sexes and ovarian dysfunction in females. Perrault syndrome may also cause neurological symptoms in some patients. Here, we present the features and genetic basis of the condition in three sisters affected by Perrault syndrome. The sisters did not have pathogenic variants in any of the genes previously associated with Perrault syndrome. We identified a change in the geneKIAA0391, encoding PRORP, a subunit of the mitochondrial RNase P complex. Mitochondrial RNase P is a key enzyme in RNA processing in mitochondria. Impaired RNA processing reduces protein production in mitochondria, which we observed in patient cells along with high levels of unprocessed RNA. When we expressed wild type PRORP in patient cells, the RNA processing improved. We also investigated PRORP localisation in the mouse inner ear and found high levels in the synapses and nerve fibers that transmit sound. It may be that disruption of RNA processing in the mitochondria of these cells causes hearing loss in this family.