Maryami F, Rismani E, Davoudi-Dehaghani E, Khalesi N, Talebi S, Mahdian R, Zeinali S. In silico Analysis of Two Novel Variants in the Pyruvate Carboxylase (PC) Gene Associated with the Severe Form of PC Deficiency.
IRANIAN BIOMEDICAL JOURNAL 2023;
27:307-19. [PMID:
37873728 PMCID:
PMC10707810 DOI:
10.61186/ibj.27.5.307]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Accepted: 06/17/2023] [Indexed: 12/17/2023]
Abstract
Background
Inborne errors of metabolism are a common cause of neonatal death. This study evaluated the acute early-onset metabolic derangement and death in two unrelated neonates.
Methods
Whole-exome sequencing (WES), Sanger sequencing, homology modeling, and in silico bioinformatics analysis were employed to assess the effects of variants on protein structure and function.
Results
WES revealed a novel homozygous variant, p.G303Afs*40 and p.R156P, in the pyruvate carboxylase (PC) gene of each neonate, which both were confirmed by Sanger sequencing. Based on the American College of Medical Genetics and Genomics guidelines, the p.G303Afs*40 was likely pathogenic, and the p.R156P was a variant of uncertain significance (VUS). Nevertheless, a known variant at position 156, the p.R156Q, was also a VUS. Protein secondary structure prediction showed changes in p.R156P and p.R156Q variants compared to the wild-type protein. However, p.G303Afs*40 depicted significant changes at C-terminal. Furthermore, comparing the interaction of wild-type and variant proteins with the ATP ligand during simulations, revealed a decreased affinity to the ATP in all the variants. Moreover, analysis of Single nucleotide polymorphism impacts on PC protein using Polyphen-2, SNAP2, FATHMM, and SNPs&GO servers predicted both R156P and R156Q as damaging variants. Likewise, free energy calculations demonstrated the destabilizing effect of both variants on PC.
Conclusion
This study confirmed the pathogenicity of both variants and suggested them as a cause of type B Pyruvate carboxylase deficiency. The results of this study would provide the family with prenatal diagnosis and expand the variant spectrum in the PC gene,which is beneficial for geneticists and endocrinologists.
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