Novel EXOSC9 variants cause pontocerebellar hypoplasia type 1D with spinal motor neuronopathy and cerebellar atrophy.

Journal of human genetics 2021 Apr

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Pontocerebellar hypoplasia (PCH) is currently classified into 13 subgroups and many gene variants associated with PCH have been identified by next generation sequencing. PCH type 1 is a rare heterogeneous neurodegenerative disorder. The clinical presentation includes early-onset severe developmental delay, progressive motor neuronopathy, and cerebellar and pontine atrophy. Recently two variants in the EXOSC9 gene (MIM: 606180), NM_001034194.1: c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161*) were identified in four unrelated patients with PCH type 1D (PCH1D) (MIM: 618065). EXOSC9 encodes a component of the exosome complex, which is essential for correct processing and degradation of RNA. We report here two PCH1D families with biallelic EXOSC9 variants: c.239T>G (p.Leu80Arg) and c.484dupA (p.Arg162Lysfs*3) in one family and c.151G>C (p.Gly51Arg) in the other family. Although the patients studied here showed similar clinical features as previously described for PCH1D, relatively greater intellectual development (although still highly restricted) and normal pontine structure were recognized. Our findings expand the clinical consequences of biallelic EXOSC9 variants.

Citation

Masamune Sakamoto, Kazuhiro Iwama, Futoshi Sekiguchi, Hideaki Mashimo, Satoko Kumada, Keiko Ishigaki, Nobuhiko Okamoto, Mahdiyeh Behnam, Mohsen Ghadami, Eriko Koshimizu, Satoko Miyatake, Satomi Mitsuhashi, Takeshi Mizuguchi, Atsushi Takata, Hirotomo Saitsu, Noriko Miyake, Naomichi Matsumoto. Novel EXOSC9 variants cause pontocerebellar hypoplasia type 1D with spinal motor neuronopathy and cerebellar atrophy. Journal of human genetics. 2021 Apr;66(4):401-407