Iranian Biomedical Journal

en In silico Analysis of Two Novel Variants in the Pyruvate Carboxylase (PC) Gene Associated with the Severe Form of PC Deficiency Molecular Genetics & Genomics Molecular Genetics & Genomics مقاله کامل Full Length/Original Article 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. Pyruvate Carboxylase, Pyruvate Carboxylase Deficiency Disease, Metabolic Diseases, Exome Sequencing 307 319 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-870-1&slc_lang=en&sid=1 Fereshteh Maryami fmaryami@yahoo.com 0000-0002-0014-9249 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St., Tehran, Iran Elham Rismani el.rismani@gmail.com 0000-0001-9997-3512 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St., Tehran, Iran Elham Davoudi-Dehaghani davoodie419419@yahoo.com 0000-0003-1429-2019 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St., Tehran, Iran Nasrin Khalesi nasrinkhalessi@yahoo.com 0000-0002-2798-3372 No Department of Pediatrics and Neonatal Intensive Care Unit, Ali-Asghar Children’s Hospital, Iran University of Medical Sciences, Tehran, Iran Saeed Talebi talebisaid@yahoo.com 0000-0002-8055-9335 No Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran Reza Mahdian Dr.reza.mahdian@gmail.com 0000-0003-1458-4767 No Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St., Tehran, Iran Sirous Zeinali zeinali@gmail.com 0000-0002-9516-9954 Yes Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Pasteur St., Tehran, Iran