Implementation of an In-House Platform for Rapid Screening of SARS-CoV-2 Genome Variations.

BACKGROUND: Global real-time monitoring of SARS-CoV-2 variants is crucial to controlling the COVID-19 outbreak. The purpose of this study was to set up a Sanger-based platform for massive SARS-CoV-2 variant tracking in laboratories in low-resource settings. METHODS: We used nested RT-PCR assay, Sanger sequencing and lineage assignment for 930-bp of the SARS-CoV-2 spike gene, which harbors specific variants of concern (VOCs) mutations. We set up our platform by comparing its results with whole genome sequencing (WGS) data on 137 SARS-CoV-2 positive samples. Then, we applied it on 1028 samples from March-September 2021. RESULTS: In total, 125 out of 137 samples showed 91.24% concordance in mutation detection. In lineage assignment, 123 out of 137 samples demonstrated 89.78% concordance, 65 of which were assigned as VOCs and showed 100% concordance. Of 1028 samples screened by our in-house method, 78 distinct mutations were detected. The most common mutations were: S:D614G (21.91%), S:P681R (12.19%), S:L452R (12.15%), S:T478K (12.15%), S:N501Y (8.91%), S:A570D (8.89%), S:P681H (8.89%), S:T716I (8.74%), S:L699I (3.50%) and S:S477N (0.28%). Of 1028 samples, 980 were attributed as VOCs, which include the Delta (B.1.617.2) and Alpha (B.1.1.7) variants. CONCLUSION: Our proposed in-house Sanger-based assay for SARS-CoV-2 lineage assignment is an accessible strategy in countries with poor infrastructure facilities. It can be applied in the rapid tracking of SARS-CoV-2 VOCs in the SARS-CoV-2 pandemic.

SARS-CoV-2 outbreak in Iran: The dynamics of the epidemic and evidence on two independent introductions.

The SARS-CoV-2 virus has been rapidly spreading globally since December 2019, triggering a pandemic, soon after its emergence. While Iran was among the first countries confronted with rapid spread of virus in February 2020, no real-time SARS-CoV-2 whole-genome tracking in early phase of outbreak was performed in the country. To address this issue, we provided 50 whole-genome sequences of viral isolates ascertained from different geographical locations in Iran during March-July 2020. The corresponding analysis on origins, transmission dynamics and genetic diversity of SARS-CoV-2 virus, represented at least two introductions of the virus into the country, constructing two major clusters defined as B.4 and B.1*. The first entry of the virus might have occurred around very late 2019/early 2020, as suggested by the time to the most recent common ancestor, followed by a rapid community transmission that led to dominancy of B.4 lineage in early epidemic till the end of June. Gradually, reduction in dominancy of B.4 occurred possibly as a result of other entries of the virus, followed by surge of B.1* lineages, as of mid-May. Remarkably, variation tracking of the virus indicated the increase in frequency of D614G mutation, along with B.1* lineages, which showed continuity till October 2020. The increase in frequency of D614G mutation and B.1* lineages from mid-May onwards predicts a rapid viral transmission that may push the country into a critical health situation followed by a considerable change in composition of viral lineages circulating in the country.

Disease Waves of SARS-CoV-2 in Iran Closely Mirror Global Pandemic Trends.

BACKGROUND: Complete SARS-CoV-2 genome sequencing in the early phase of the outbreak in Iran showed two independent viral entries. Subsequently, as part of a genome surveillance project, we aimed to characterize the genetic diversity of SARS-CoV-2 in Iran over one year after emerging. METHODS: We provided 319 SARS-CoV-2 whole-genome sequences used to monitor circulating lineages in March 2020-May 2021 time interval. RESULTS: The temporal dynamics of major SARS-CoV-2 clades/lineages circulating in Iran is comparable to the global perspective and represent the 19A clade (B.4) dominating the first disease wave, followed by 20A (B.1.36), 20B (B.1.1.413), 20I (B.1.1.7), leading the second, third and fourth waves, respectively. We observed a mixture of circulating B.1.36, B.1.1.413, B.1.1.7 lineages in winter 2021, paralleled in a fading manner for B.1.36/B.1.1.413 and a growing rise for B.1.1.7, prompting the fourth outbreak. Entry of the Delta variant, leading to the fifth disease wave in summer 2021, was detected in April 2021. This study highlights three lineages as hallmarks of the SARS-CoV-2 outbreak in Iran; B4, dominating early periods of the epidemic, B.1.1.413 (B.1.1 with the combination of [D138Y-S477N-D614G] spike mutations) as a characterizing lineage in Iran, and the co-occurrence of [I100T-L699I] spike mutations in half of B.1.1.7 sequences mediating the fourth peak. It also designates the renowned combination of G and GR clades' mutations as the top recurrent mutations. CONCLUSION: In brief, we provided a real-time and comprehensive picture of the SARS-CoV-2 genetic diversity in Iran and shed light on the SARS-CoV-2 transmission and circulation on the regional scale.

Exome sequencing utility in defining the genetic landscape of hearing loss and novel-gene discovery in Iran.

Hearing loss (HL) is one of the most common sensory defects affecting more than 466 million individuals worldwide. It is clinically and genetically heterogeneous with over 120 genes causing non-syndromic HL identified to date. Here, we performed exome sequencing (ES) on a cohort of Iranian families with no disease-causing variants in known deafness-associated genes after screening with a targeted gene panel. We identified likely causal variants in 20 out of 71 families screened. Fifteen families segregated variants in known deafness-associated genes. Eight families segregated variants in novel candidate genes for HL: DBH, TOP3A, COX18, USP31, TCF19, SCP2, TENM1, and CARMIL1. In the three of these families, intrafamilial locus heterogeneity was observed with variants in both known and novel candidate genes. In aggregate, we were able to identify the underlying genetic cause of HL in nearly 30% of our study cohort using ES. This study corroborates the observation that high-throughput DNA sequencing in populations with high rates of consanguineous marriages represents a more appropriate strategy to elucidate the genetic etiology of heterogeneous conditions such as HL.

Contribution of Iran in Elucidating the Genetic Causes of Autosomal Recessive Intellectual Disability.

Many genes with different inheritance modes contribute to the pathogenicity of intellectual disability (ID) making it the most known genetically heterogeneous disorder. Advanced next-generation sequencing (NGS) technologies have helped researchers identify genes underlying ID at an exponential pace. As a consanguineous country, Iran is a hotspot for discovering novel autosomal recessive intellectual disability (ARID) genes. Here, we aimed to review and compare reported ARID gene discovery both in Iran and globally, and pinpoint the research areas that need to be developed in future. We studied published articles and reviews on all known ID genes. In parallel, the gene-discovery research carried out on the Iranian population were also reviewed to determine the contribution of Iran to identifying novel ID genes. Also we tried to find supporting evidence on the causative role of novel genes identified in Iran including confirmatory functional studies and existence of more affected families. We also briefly reviewed the current therapeutic approaches under development for a subset of eligible ID cases. In total, 8% of all ID and 11.5% of all ARID genes described so far have been identified via studies on Iranian population. Functional studies have been performed on 29% of the genes identified in Iran. More than one affected family has been reported for many of these genes, supporting their causative role in ID pathogenesis. Despite the notable contribution of Iran in gene-discovery research, further functional studies on the identified genes are required.