Author(s):
Encarnação, Marisa ; Coutinho, Maria Francisca ; Cho, Soo Min ; Cardoso, Maria Teresa ; Ribeiro, Isaura ; Chaves, Paulo ; Santos, Juliana Inês ; Quelhas, D ; Lacerda, Lucia ; Leão Teles, Elisa ; Futerman, Anthony H. ; Vilarinho, Laura ; Alves, Sandra
Date: 2020
Persistent ID: http://hdl.handle.net/10400.16/2678
Origin: Repositório Científico da Unidade Local de Saúde de Santo António (ULSSA)
Subject(s): NPC1; Niemann-Pick type C; RNA-seq; exon skipping; silent variant; unfolded protein response
Description
Background: Niemann-Pick type C (NPC, MIM #257220) is a neuro-visceral disease, caused predominantly by pathogenic variants in the NPC1 gene. Here we studied patients with clinical diagnosis of NPC but inconclusive results regarding the molecular analysis. Methods: We used a Next-Generation Sequencing (NGS)-panel followed by cDNA analysis. Latter, we used massively parallel single-cell RNA-seq (MARS-Seq) to address gene profiling changes and finally the effect of different variants on the protein and cellular levels. Results: We identified novel variants and cDNA analysis allowed us to establish the functional effect of a silent variant, previously reported as a polymorphism. We demonstrated that this variant induces the skipping of exon 11 leading to a premature stop codon and identified it in NPC patients from two unrelated families. MARS-Seq analysis showed that a number of upregulated genes were related to the unfolded protein response (UPR) and endoplasmic reticulum (ER) stress in one specific patient. Also, for all analyzed variants, the NPC1 protein was partially retained in the ER. Conclusion: We showed that the NPC1 silent polymorphism (p.V562V) is a disease-causing variant in NPC and that the UPR is upregulated in an NPC patient.
