Pontocerebellar hypoplasia (PCH) is an autosomal recessive, neurodegenerative disorder with multiple subtypes leading to severe neurodevelopmental disabilities. PCH type 1 D is linked to alterations in the EXOSC9 gene. EXOSC9 is a component of the RNA exosome, an evolutionarily conserved ribonuclease complex essential for RNA degradation and processing. The clinical phenotype is characterized by cerebellar and pontine hypoplasia associated with motor neuronopathy. To date, nine patients have been reported in the literature with PCH1D. We report the case of an infant with PCH type 1D due to two variants in the EXOCS9 gene (NM_001034194.1: c.41T>C-p.Leu14Pro) and a novel variant (c.643C>T-p.Arg212*). This report thoroughly reviews the literature PCH1D and highlights the crucial role of the exosome in cellular homeostasis.
Keywords: EXOSC9; cerebellar atrophy; motor neuron disease; pontocerebellar hypoplasia; spinal motor neuronopathy.