Identification of Missense ADGRV1 Mutation as a Candidate Genetic Cause of Familial Febrile Seizure 4

Febrile seizure (FS) is related to a febrile illness (temperature > 38 °C) not caused by an infection of central nervous system, without neurologic deficits in children aged 6–60 months. The family study implied a polygenic model in the families of proband(s) with single FS, however in families with repeated FS, inheritance was matched to autosomal dominance with reduced disease penetrance. A 20 month-old girl showed recurrent FS and afebrile seizures without developmental delay or intellectual disability. The seizures disappeared after 60 months without anti-seizure medication. The 35 year-old proband’s mother also experienced five episodes of simple FS and two episodes of unprovoked seizures before 5 years old. Targeted exome sequencing was conducted along with epilepsy/seizure-associated gene-filtering to identify the candidate causative mutation. As a result, a heterozygous c.2039A>G of the ADGRV1 gene leading to a codon change of aspartic acid to glycine at the position 680 (rs547076322) was identified. This protein’s glycine residue is highly conserved, and its allele frequency is 0.00002827 in the gnomAD population database. ADGRV1 mutation may have an influential role in the occurrence of genetic epilepsies, especially those with febrile and afebrile seizures. Further investigation of ADGRV1 mutations is needed to prove that it is a significant susceptible gene for febrile and/or afebrile seizures in early childhood.

Genomic Variations in ORF3a and ORF1ab Genes of SARS-nCoV2 Strain from Southern Pakistan

Emergence of COVID-19 pandemic has resulted in 8,578,283 total cases and 456,286 deaths worldwide as of June 19, 2020. We previously analysed genomic variants in two Northern Pakistani SARS-nCoV2 strains against USA and Chinese strains as reference, and hypothesized the putative role of observed variants in low severity of COVID-19 in Pakistan. Due to high variation rate in this virus, we further analysed the whole genome of Southern Pakistani SARS-nCoV2 MT500122 strain (Karachi-Pak) vs NC_045512 (Wuhan1-China) and observed 4 variants (3=SNPs,1=del). Three of variants at g.1604 (del ND447N), SNPs at g.1912 (p.=), g.10582 (p.=) and g.26022 (p.=) in ORF1ab and ORF3a genes respectively. ORF1ab encodes 16 non-structural polyproteins (nsps1-16) and plays role in viral replication. The codon change deletion in its sequence (as observed in MT500122) might have caused conformational alterations particularly in nsp2&5 structures which may obstruct its effectiveness. ORF3a is unique to SARS-nCoV2 and located in-between envelope and spike genes, which assist viral entry into the host cell by interacting with S gene. Alteration in its sequence might have hampered the activation of S gene and affect its binding capacity to host cell ACE2 and NRP1 receptors, which may greatly weaken its pathogenicity in its different strains and hence may vary severity of COVID-19. Nevertheless, intensive data and conclusive wet lab experiments are needed for validating this postulated hypothesis. Moreover, these variants have modifier to silent impact on further 9 genes e.g. M, N, S, E, ORFs 6, 7a, 7b, 8 and 10 as well. Advancements in understanding the role of these Pakistani SARS-nCoV2 genomic variations will be helpful in developing indigenous vaccines, diagnostic kits and drug development.

Congenital Hypoparathyroidism Associated With Elevated Circulating Nonfunctional Parathyroid Hormone Due to Novel PTH Mutation

Context Familial hypoparathyroidism has a heterogeneous presentation where patients usually have low parathyroid hormone (PTH) levels due to impaired production or secretion. This contrasts with pseudohypoparathyroidism, in which PTH resistance is usually associated with an elevated serum PTH. High levels of circulating PTH can also be due to bioinactive PTH, which is difficult to distinguish from pseudohypoparathyroidism on biochemical grounds. Case Description We report on 2 sisters from consanguineous parents who presented with tetany at birth and were diagnosed with congenital hypocalcemia. Serum PTH levels were normal for many years, but progressively increased in midadulthood to greater than 100x the upper limit of normal on multiple assays. Homozygosity mapping was performed on 1 sister that demonstrated loss of heterozygosity (LOH) around PTH. Sequencing revealed a previously unreported variant, c.94T>C, predicting a codon change of p.Ser32Pro that is biologically inactive. Conclusions This case report shows a previously unreported unusual biochemical phenotype of a rising PTH in the context of a novel PTH mutation. This expands the evolving genotypes associated with hypoparathyroidism without established gene mutations.

Gain-of-function IKBKB mutation causes human combined immune deficiency

Genetic mutations account for many devastating early onset immune deficiencies. In contrast, less severe and later onset immune diseases, including in patients with no prior family history, remain poorly understood. Whole exome sequencing in two cohorts of such patients identified a novel heterozygous de novo IKBKB missense mutation (c.607G>A) in two separate kindreds in whom probands presented with immune dysregulation, combined T and B cell deficiency, inflammation, and epithelial defects. IKBKB encodes IKK2, which activates NF-κB signaling. IKK2V203I results in enhanced NF-κB signaling, as well as T and B cell functional defects. IKK2V203 is a highly conserved residue, and to prove causation, we generated an accurate mouse model by introducing the precise orthologous codon change in Ikbkb using CRISPR/Cas9. Mice and humans carrying this missense mutation exhibit remarkably similar cellular and biochemical phenotypes. Accurate mouse models engineered by CRISPR/Cas9 can help characterize novel syndromes arising from de novo germline mutations and yield insight into pathogenesis.

Deleterious Effect of the QoInhibitor Compound Resistance-Conferring Mutation G143A in the Intron-Containing CytochromebGene and Mechanisms for Bypassing It

ABSTRACTThe mutation G143A in the inhibitor binding site of cytochromebconfers a high level of resistance to fungicides targeting thebc1complex. The mutation, reported in many plant-pathogenic fungi, has not evolved in fungi that harbor an intron immediately after the codon for G143 in the cytochromebgene, intron bi2. UsingSaccharomycescerevisiaeas a model organism, we show here that a codon change from GGT to GCT, which replaces glycine 143 with alanine, hinders the splicing of bi2 by altering the exon/intron structure needed for efficient intron excision. This lowers the levels of cytochromeband respiratory growth. We then investigated possible bypass mechanisms that would restore the respiratory fitness of a resistant mutant. Secondary mutations in the mitochondrial genome were found, including a point mutation in bi2 restoring the correct exon/intron structure and the deletion of intron bi2. We also found that overexpression of nuclear genesMRS2andMRS3, encoding mitochondrial metal ion carriers, partially restores the respiratory growth of the G143A mutant. Interestingly, theMRS3gene from the plant-pathogenic fungusBotrytiscinerea, overexpressed in anS.cerevisiaeG143A mutant, had a similar compensatory effect. These bypass mechanisms identified in yeast could potentially arise in pathogenic fungi.