Adaptive sequencing using nanopores and deep learning of mitochondrial DNA.

Nanopore sequencing is an emerging technology that reads DNA by utilizing a unique method of detecting nucleic acid sequences and identifies the various chemical modifications they carry. Deep learning has increased in popularity as a useful technique to solve many complex computational tasks. 'Adaptive sequencing' is an implementation of selective sequencing, intended for use on the nanopore sequencing platform. In this study, we demonstrated an alternative method of software-based selective sequencing that is performed in real time by combining nanopore sequencing and deep learning. Our results showed the feasibility of using deep learning for classifying signals from only the first 200 nucleotides in a raw nanopore sequencing signal format. This was further demonstrated by comparing the accuracy of our deep learning classification model across data from several human cell lines and other eukaryotic organisms. We used custom deep learning models and a script that utilizes a 'Read Until' framework to target mitochondrial molecules in real time from a human cell line sample. This achieved a significant separation and enrichment ability of 2.3-fold. In a series of very short sequencing experiments (10, 30 and 120 min), we identified genomic and mitochondrial reads with accuracy above 90%, although mitochondrial DNA comprised only 0.1% of the total input material. The uniqueness of our method is the ability to distinguish two groups of DNA even without a labeled reference. This contrasts with studies that required a well-defined reference, whether of a DNA sequence or of another type of representation. Additionally, our method showed higher correlation to the theoretically possible enrichment factor, compared with other published methods. We believe that our results will lay the foundation for rapid and selective sequencing using nanopore technology and will pave the approach for clinical applications that use nanopore sequencing data.

Prediction of sustained opioid use in children and adolescents using machine learning.

BACKGROUND: Opioid misuse in the paediatric population is understudied. This study aimed to develop a machine learning classifier to differentiate between occasional and sustained opioid users among children and adolescents in outpatient settings. METHODS: Data for 29,335 patients under 19 yr with recorded opioid purchases were collected from medical records. Machine learning methods were applied to predict sustained opioid use within 1, 2, or 3 yr after first opioid use, using sociodemographic information, medical history, and healthcare usage variables collected near the time of first prescription fulfilment. The models' performance was evaluated with classification and calibration metrics, and a decision curve analysis. An online tool was deployed for model self-exploration and visualisation. RESULTS: The models demonstrated good performance, with a 1-yr follow-up model achieving a sensitivity of 0.772, a specificity of 0.703, and an ROC-AUC of 0.792 on an independent test set, with calibration intercept and slope of 0.00 and 1.02, respectively. Decision curve analysis revealed the clinical benefit of using the model relative to other strategies. SHAP analysis (SHapley Additive exPlanations) identified influential variables, including the number of diagnoses, medical images, laboratory tests, and type of opioid used. CONCLUSIONS: Our model showed promising performance in predicting sustained opioid use among paediatric patients. The online risk prediction tool can facilitate compliance to such tools by clinicians. This study presents the potential of machine learning in identifying at-risk paediatric populations for sustained opioid use, potentially contributing to secondary prevention of opioid abuse.

Machine learning-enhanced noninvasive prenatal testing of monogenic disorders.

OBJECTIVE: Single-nucleotide variants (SNVs) are of great significance in prenatal diagnosis as they are the leading cause of inherited single-gene disorders (SGDs). Identifying SNVs in a non-invasive prenatal screening (NIPS) scenario is particularly challenging for maternally inherited SNVs. We present an improved method to predict inherited SNVs from maternal or paternal origin in a genome-wide manner. METHODS: We performed SNV-NIPS based on the combination of fragments of cell free DNA (cfDNA) features, Bayesian inference and a machine-learning (ML) prediction refinement step using random forest (RF) classifiers trained on millions of non-pathogenic variants. We next evaluate the real-world performance of our refined method in a clinical setting by testing our models on 16 families with singleton pregnancies and varying fetal fraction (FF) levels, and validate the results over millions of inherited variants in each fetus. RESULTS: The average area under the ROC curve (AUC) values are 0.996 over all families for paternally inherited variants, 0.81 for the challenging maternally inherited variants, 0.86 for homozygous biallelic variants and 0.95 for compound heterozygous variants. Discriminative AUCs were achieved even in families with a low FF. We further investigate the performance of our method in correctly predicting SNVs in coding regions of clinically relevant genes and demonstrate significantly improved AUCs in these regions. Finally, we focus on the pathogenic variants in our cohort and show that our method correctly predicts if the fetus is unaffected or affected in all (10/10, 100%) of the families containing a pathogenic SNV. CONCLUSIONS: Overall, we demonstrate our ability to perform genome-wide NIPS for maternal and homozygous biallelic variants and showcase the utility of our method in a clinical setting.

TWIST1 methylation by SETD6 selectively antagonizes LINC-PINT expression in glioma.

Gliomas are one of the most common and lethal brain tumors among adults. One process that contributes to glioma progression and recurrence is the epithelial to mesenchymal transition (EMT). EMT is regulated by a set of defined transcription factors which tightly regulate this process, among them is the basic helix-loop-helix family member, TWIST1. Here we show that TWIST1 is methylated on lysine-33 at chromatin by SETD6, a methyltransferase with expression levels correlating with poor survival in glioma patients. RNA-seq analysis in U251 glioma cells suggested that both SETD6 and TWIST1 regulate cell adhesion and migration processes. We further show that TWIST1 methylation attenuates the expression of the long-non-coding RNA, LINC-PINT, thereby promoting EMT in glioma. Mechanistically, TWIST1 methylation represses the transcription of LINC-PINT by increasing the occupancy of EZH2 and the catalysis of the repressive H3K27me3 mark at the LINC-PINT locus. Under un-methylated conditions, TWIST1 dissociates from the LINC-PINT locus, allowing the expression of LINC-PINT which leads to increased cell adhesion and decreased cell migration. Together, our findings unravel a new mechanistic dimension for selective expression of LINC-PINT mediated by TWIST1 methylation.

Deoxyhypusine hydroxylase: A novel therapeutic target differentially expressed in short-term vs long-term survivors of glioblastoma.

Glioblastoma (GB) is the most aggressive neoplasm of the brain. Poor prognosis is mainly attributed to tumor heterogeneity, invasiveness and drug resistance. Only a small fraction of GB patients survives longer than 24 months from the time of diagnosis (ie, long-term survivors [LTS]). In our study, we aimed to identify molecular markers associated with favorable GB prognosis as a basis to develop therapeutic applications to improve patients' outcome. We have recently assembled a proteogenomic dataset of 87 GB clinical samples of varying survival rates. Following RNA-seq and mass spectrometry (MS)-based proteomics analysis, we identified several differentially expressed genes and proteins, including some known cancer-related pathways and some less established that showed higher expression in short-term (<6 months) survivors (STS) compared to LTS. One such target found was deoxyhypusine hydroxylase (DOHH), which is known to be involved in the biosynthesis of hypusine, an unusual amino acid essential for the function of the eukaryotic translation initiation factor 5A (eIF5A), which promotes tumor growth. We consequently validated DOHH overexpression in STS samples by quantitative polymerase chain reaction (qPCR) and immunohistochemistry. We further showed robust inhibition of proliferation, migration and invasion of GB cells following silencing of DOHH with short hairpin RNA (shRNA) or inhibition of its activity with small molecules, ciclopirox and deferiprone. Moreover, DOHH silencing led to significant inhibition of tumor progression and prolonged survival in GB mouse models. Searching for a potential mechanism by which DOHH promotes tumor aggressiveness, we found that it supports the transition of GB cells to a more invasive phenotype via epithelial-mesenchymal transition (EMT)-related pathways.

Population differences in antibody response to SARS-CoV-2 infection and BNT162b2 vaccination.

The concentration of SARS-CoV-2-specific serum antibodies, elicited by vaccination or infection, is a primary determinant of anti-viral immunity, which correlates with protection against infection and COVID-19. Serum samples were obtained from 25 897 participants and assayed for anti-SARS-CoV-2 spike protein RBD IgG antibodies. The cohort was composed of newly vaccinated BNT162b2 recipients, in the first month or 6 months after vaccination, COVID-19 patients and a general sample of the Israeli population. Antibody levels of BNT162b2 vaccine recipients were negatively correlated with age, with a prominent decrease in recipients over 55 years old, which was most significant in males. This trend was observable within the first month and 6 months after vaccination, while younger participants were more likely to maintain stable levels of serum antibodies. The antibody concentration of participants previously infected with SARS-CoV-2 was lower than the vaccinated and had a more complex, non-linear relation to age, sex and COVID-19 symptoms. Taken together, our data supports age and sex as primary determining factors for both the magnitude and durability of humoral response to SARS-CoV-2 infection and the COVID-19 vaccine. Our results could inform vaccination policies, prioritizing the most susceptible populations for repeated vaccination.

Oral microbiota signatures in post-traumatic stress disorder (PTSD) veterans.

Post-traumatic stress disorder (PTSD) represents a global public health concern, affecting about 1 in 20 individuals. The symptoms of PTSD include intrusiveness (involuntary nightmares or flashbacks), avoidance of traumatic memories, negative alterations in cognition and mood (such as negative beliefs about oneself or social detachment), increased arousal and reactivity with irritable reckless behavior, concentration problems, and sleep disturbances. PTSD is also highly comorbid with anxiety, depression, and substance abuse. To advance the field from subjective, self-reported psychological measurements to objective molecular biomarkers while considering environmental influences, we examined a unique cohort of Israeli veterans who participated in the 1982 Lebanon war. Non-invasive oral 16S RNA sequencing was correlated with psychological phenotyping. Thus, a microbiota signature (i.e., decreased levels of the bacteria sp_HMT_914, 332 and 871 and Noxia) was correlated with PTSD severity, as exemplified by intrusiveness, arousal, and reactivity, as well as additional psychopathological symptoms, including anxiety, hostility, memory difficulties, and idiopathic pain. In contrast, education duration correlated with significantly increased levels of sp_HMT_871 and decreased levels of Bacteroidetes and Firmicutes, and presented an inverted correlation with adverse psychopathological measures. Air pollution was positively correlated with PTSD symptoms, psychopathological symptoms, and microbiota composition. Arousal and reactivity symptoms were correlated with reductions in transaldolase, an enzyme controlling a major cellular energy pathway, that potentially accelerates aging. In conclusion, the newly discovered bacterial signature, whether an outcome or a consequence of PTSD, could allow for objective soldier deployment and stratification according to decreases in sp_HMT_914, 332, 871, and Noxia levels, coupled with increases in Bacteroidetes levels. These findings also raise the possibility of microbiota pathway-related non-intrusive treatments for PTSD.

Dominant frontonasal dysplasia with ectodermal defects results from increased activity of ALX4.

Frontonasal dysplasia (FND) refers to a group of rare developmental disorders characterized by abnormal morphology of the craniofacial region. We studied a family manifesting with clinical features typical for FND2 including neurobehavioral abnormalities, hypotrichosis, hypodontia, and facial dysmorphism. Whole-exome sequencing analysis identified a novel heterozygous frameshift insertion in ALX4 (c.985_986insGTGC, p.Pro329Argfs*115), encoding aristaless homeobox 4. This and a previously reported dominant FND2-causing variant are predicted to result in the formation of a similar abnormally elongated protein tail domain. Using a reporter assay, we showed that the elongated ALX4 displays increased activity. ALX4 negatively regulates the Wnt/ß-catenin pathway and accordingly, patient keratinocytes showed altered expression of genes associated with the WNT/ß-catenin pathway, which in turn may underlie ectodermal manifestations in FND2. In conclusion, dominant FND2 with ectodermal dysplasia results from frameshift variants in ALX4 exerting a gain-of-function effect.

Can RNA Affect Memory Modulation? Implications for PTSD Understanding and Treatment.

Memories are a central aspect of our lives, but the mechanisms underlying their formation, consolidation, retrieval, and extinction remain poorly understood. In this review, we explore the molecular mechanisms of memory modulation and investigate the effects of RNA on these processes. Specifically, we examine the effects of time and location on gene expression alterations. We then discuss the potential for harnessing these alterations to modulate memories, particularly fear memories, to alleviate post-traumatic stress disorder (PTSD) symptoms. The current state of research suggests that transcriptional changes play a major role in memory modulation and targeting them through microRNAs may hold promise as a novel approach for treating memory-related disorders such as PTSD.

PNPT1, MYO15A, PTPRQ, and SLC12A2-associated genetic and phenotypic heterogeneity among hearing impaired assortative mating families in Southern India.

The study was conducted between 2018 and 2020. From a cohort of 113 hearing impaired (HI), five non-DFNB12 probands identified with heterozygous CDH23 variants were subjected to exome analysis. This resolved the etiology of hearing loss (HL) in four South Indian assortative mating families. Six variants, including three novel ones, were identified in four genes: PNPT1 p.(Ala46Gly) and p.(Asn540Ser), MYO15A p.(Leu1485Pro) and p.(Tyr1891Ter), PTPRQ p.(Gln1336Ter), and SLC12A2 p.(Pro988Ser). Compound heterozygous PNPT1 variants were associated with DFNB70 causing prelingual profound sensorineural hearing loss (SNHL), vestibular dysfunction, and unilateral progressive vision loss in one family. In the second family, MYO15A variants in the myosin motor domain, including a novel variant, causing DFNB3, were found to be associated with prelingual profound SNHL. A novel PTPRQ variant was associated with postlingual progressive sensorineural/mixed HL and vestibular dysfunction in the third family with DFNB84A. In the fourth family, the SLC12A2 novel variant was found to segregate with severe-to-profound HL causing DFNA78, across three generations. Our results suggest a high level of allelic, genotypic, and phenotypic heterogeneity of HL in these families. This study is the first to report the association of PNPT1, PTPRQ, and SLC12A2 variants with HL in the Indian population.

Variant PADI3 in Central Centrifugal Cicatricial Alopecia.

BACKGROUND: Central centrifugal cicatricial alopecia (CCCA) is the most common form of scarring alopecia among women of African ancestry. The disease is occasionally observed to affect women in families in a manner that suggests an autosomal dominant trait and usually manifests clinically after intense hair grooming. We sought to determine whether there exists a genetic basis of CCCA and, if so, what it is. METHODS: We used exome sequencing in a group of women with alopecia (discovery set), compared the results with those in a public repository, and applied other filtering criteria to identify candidate genes. We then performed direct sequencing to identify disease-associated DNA variations and RNA sequencing, protein modeling, immunofluorescence staining, immunoblotting, and an enzymatic assay to evaluate the consequences of potential etiologic mutations. We used a replication set that consisted of women with CCCA to confirm the data obtained with the discovery set. RESULTS: In the discovery set, which included 16 patients, we identified one splice site and three heterozygous missense mutations in PADI3 in 5 patients (31%). (The approximate prevalence of the disease is up to 5.6%.) PADI3 encodes peptidyl arginine deiminase, type III (PADI3), an enzyme that post-translationally modifies other proteins that are essential to hair-shaft formation. All three CCCA-associated missense mutations in PADI3 affect highly conserved residues and are predicted to be pathogenic; protein modeling suggests that they result in protein misfolding. These mutations were found to result in reduced PADI3 expression, abnormal intracellular localization of the protein, and decreased enzymatic activity - findings that support their pathogenicity. Immunofluorescence staining showed decreased expression of PADI3 in biopsy samples of scalp skin obtained from patients with CCCA. We then directly sequenced PADI3 in an additional 42 patients (replication set) and observed genetic variants in 9 of them. A post hoc analysis of the combined data sets showed that the prevalence of PADI3 mutation was higher among patients with CCCA than in a control cohort of women of African ancestry (P = 0.002 by the chi-square test; P = 0.006 by Fisher's exact test; and after adjustment for relatedness of persons, P = 0.03 and P = 0.04, respectively). CONCLUSIONS: Mutations in PADI3, which encodes a protein that is essential to proper hair-shaft formation, were associated with CCCA. (Funded by the Ram Family Foundation and others.).

Bayesian-based noninvasive prenatal diagnosis of single-gene disorders.

In the last decade, noninvasive prenatal diagnosis (NIPD) has emerged as an effective procedure for early detection of inherited diseases during pregnancy. This technique is based on using cell-free DNA (cfDNA) and fetal cfDNA (cffDNA) in maternal blood, and hence, has minimal risk for the mother and fetus compared with invasive techniques. NIPD is currently used for identifying chromosomal abnormalities (in some instances) and for single-gene disorders (SGDs) of paternal origin. However, for SGDs of maternal origin, sensitivity poses a challenge that limits the testing to one genetic disorder at a time. Here, we present a Bayesian method for the NIPD of monogenic diseases that is independent of the mode of inheritance and parental origin. Furthermore, we show that accounting for differences in the length distribution of fetal- and maternal-derived cfDNA fragments results in increased accuracy. Our model is the first to predict inherited insertions-deletions (indels). The method described can serve as a general framework for the NIPD of SGDs; this will facilitate easy integration of further improvements. One such improvement that is presented in the current study is a machine learning model that corrects errors based on patterns found in previously processed data. Overall, we show that next-generation sequencing (NGS) can be used for the NIPD of a wide range of monogenic diseases, simultaneously. We believe that our study will lead to the achievement of a comprehensive NIPD for monogenic diseases.

DYRK1B haploinsufficiency in a family with metabolic syndrome and abnormal cognition.

A family with DYRK1B LOF variant offering to expand the phenotype beyond the metabolic syndrome.

Microdeletion of 16q24.1-q24.2-A unique etiology of Lymphedema-Distichiasis syndrome and neurodevelopmental disorder.

Interstitial deletions of 16q24.1-q24.2 are associated with alveolar capillary dysplasia, congenital renal malformations, neurodevelopmental disorders, and congenital abnormalities. Lymphedema-Distichiasis syndrome (LDS; OMIM # 153400) is a dominant condition caused by heterozygous pathogenic variants in FOXC2. Usually, lymphedema and distichiasis occur in puberty or later on, and affected individuals typically achieve normal developmental milestones. Here, we describe a boy with congenital lymphedema, distichiasis, bilateral hydronephrosis, and global developmental delay, with a de novo microdeletion of 894 kb at 16q24.1-q24.2. This report extends the phenotype of both 16q24.1-q24.2 microdeletion syndrome and of LDS. Interestingly, the deletion involves only the 3'-UTR part of FOXC2.

Transcriptomic Analysis of Human Fragile X Syndrome Neurons Reveals Neurite Outgrowth Modulation by the TGFß/BMP Pathway.

Fragile X Syndrome (FXS) is the main genetic reason for intellectual disability and is caused by the silencing of fragile X mental retardation protein (FMRP), an RNA-binding protein regulating the translation of many neuronal mRNAs. Neural differentiation of FX human embryonic stem cells (hESC) mimics the neurodevelopment of FXS fetuses and thus serves as a good model to explore the mechanisms underlining the development of FXS. Isogenic hESC clones with and without the FX mutation that share the same genetic background were in vitro differentiated into neurons, and their transcriptome was analyzed by RNA sequencing. FX neurons inactivating FMR1 expression presented delayed neuronal development and maturation, concomitant with dysregulation of the TGFß/BMP signaling pathway, and genes related to the extracellular matrix. Migration assay showed decreased neurite outgrowth in FX neurons that was rescued by inhibition of the TGFß/BMP signaling pathway. Our results provide new insights into the molecular pathway by which loss of FMRP affects neuronal network development. In FX neurons, the lack of FMRP dysregulates members of the BMP signaling pathway associated with ECM organization which, in a yet unknown mechanism, reduces the guidance of axonal growth cones, probably leading to the aberrant neuronal network function seen in FXS.

Blood RNA Sequencing Indicates Upregulated BATF2 and LY6E and Downregulated ISG15 and MT2A Expression in Children with Autism Spectrum Disorder.

Mutations in over 100 genes are implicated in autism spectrum disorder (ASD). DNA SNPs, CNVs, and epigenomic modifications also contribute to ASD. Transcriptomics analysis of blood samples may offer clues for pathways dysregulated in ASD. To expand and validate published findings of RNA-sequencing (RNA-seq) studies, we performed RNA-seq of whole blood samples from an Israeli discovery cohort of eight children with ASD compared with nine age- and sex-matched neurotypical children. This revealed 10 genes with differential expression. Using quantitative real-time PCR, we compared RNAs from whole blood samples of 73 Israeli and American children with ASD and 26 matched neurotypical children for the 10 dysregulated genes detected by RNA-seq. This revealed higher expression levels of the pro-inflammatory transcripts BATF2 and LY6E and lower expression levels of the anti-inflammatory transcripts ISG15 and MT2A in the ASD compared to neurotypical children. BATF2 was recently reported as upregulated in blood samples of Japanese adults with ASD. Our findings support an involvement of these genes in ASD phenotypes, independent of age and ethnicity. Upregulation of BATF2 and downregulation of ISG15 and MT2A were reported to reduce cancer risk. Implications of the dysregulated genes for pro-inflammatory phenotypes, immunity, and cancer risk in ASD are discussed.

Re-evaluating the pathogenicity of the c.783+2T>C BAP1 germline variant.

BAP1 germline pathogenic sequence variants (PSVs) underlie a unique tumor predisposition syndrome (BAP1-TPDS) associated with an increased lifetime risk for developing primarily pleural and peritoneal mesothelioma and uveal and cutaneous melanoma. Overwhelmingly, BAP1 PSVs are unique, family-specific inactivating variants. We identified seven families, six of Jewish Iraqi origin, harboring an identical BAP1 splice variant (c.783+2T>C), currently assigned a "likely pathogenic" status. Given a nonclassical BAP1-TPDS tumor type clustering and low penetrance in these families, the pathogenicity of this variant was re-evaluated by a combined approach including literature analysis, revised bioinformatics analysis, allelic loss, effect on the transcript, and tumor protein expression patterns. None of the three available tumors showed an allelic loss, there was no discernable effect on alternative splicing based on reverse-transcription polymerase chain reaction, and there was no decrease or loss of somatic protein expression in 2/3 analyzed tumors. This led to assigning a Benign Strong (BS) criteria, BS4, supporting BS3 criteria, and weakening the Pathogenic Supporting (PP) criteria PP5. Combined, these data suggest that this sequence variant should be reclassified as a variant of unknown significance by American College of Medical Genetics (ACMG) criteria.

Two intronic cis-acting variants in both alleles of the POLR3A gene cause progressive spastic ataxia with hypodontia.

POLR3A encodes the largest subunit of the DNA-dependent RNA polymerase III. Pathogenic variants in this gene are associated with dysregulation of tRNA production and other non-coding RNAs. POLR3A-related disorders include variable phenotypes. The genotype-phenotype correlation is still unclear. Phenotypic analysis and exome sequencing were performed in four affected siblings diagnosed clinically with hereditary spastic ataxia, two healthy siblings and their unaffected mother. All four affected siblings (ages 46-55) had similar clinical features of early childhood-onset hypodontia and adolescent-onset progressive spastic ataxia. None had progeria, gonadal dysfunction or dysmorphism. All affected individuals had biallelic POLR3A pathogenic variants composed by two cis-acting intronic splicing-altering variants, c.1909 + 22G > A and c.3337-11 T > C. The two healthy siblings had wild-type alleles. The mother and another unaffected sibling were heterozygous for the allele containing both variants. This is the first report addressing the clinical consequence associated with homozygosity for a unique pathogenic intronic allele in the POLR3A gene. This allele was previously reported in compound heterozygous combinations in patients with Wiedemann-Rautenstrauch syndrome, a severe progeroid POLR3A-associated phenotype. We show that homozygosity for this allele is associated with spastic ataxia with hypodontia, and not with progeroid features. These findings contribute to the characterization of genotype-phenotype correlation in POLR3A-related disorders.

Molecular epidemiology of non-syndromic autosomal recessive congenital ichthyosis in a Middle-Eastern population.

Autosomal recessive congenital ichthyosis (ARCI) is a rare and heterogeneous skin cornification disorder presenting with generalized scaling and varying degrees of erythema. Clinical manifestations range from lamellar ichthyosis (LI), congenital ichthyosiform erythroderma (CIE) through the most severe form of ARCI, Harlequin ichthyosis (HI). We used homozygosity mapping, whole-exome and direct sequencing to delineate the relative distribution of pathogenic variants as well as identify genotype-phenotype correlations in a cohort of 62 Middle Eastern families with ARCI of various ethnic backgrounds. Pathogenic variants were identified in most ARCI-associated genes including TGM1 (21%), CYP4F22 (18%), ALOX12B (14%), ABCA12 (10%), ALOXE3 (6%), NIPAL4 (5%), PNPLA1 (3%), LIPN (2%) and SDR9C7 (2%). In 19% of cases, no mutation was identified. Our cohort revealed a higher prevalence of CYP4F22 and ABCA12 pathogenic variants and a lower prevalence of TGM1 and NIPAL4 variants, as compared to data obtained in other regions of the world. Most variants (89%) in ALOX12B were associated with CIE and were the most common cause of ARCI among patients of Muslim origin (26%). Palmoplantar keratoderma associated with fissures was exclusively a result of pathogenic variants in TGM1. To our knowledge, this is the largest cohort study of ARCI in the Middle-Eastern population reported to date. Our data demonstrate the importance of population-tailored mutation screening strategies and shed light upon specific genotype-phenotype correlations.

Ethnic differences in alpha-1 antitrypsin deficiency allele frequencies may partially explain national differences in COVID-19 fatality rates.

Infection rates, severity, and fatalities due to COVID-19, the pandemic mediated by SARS-CoV-2, vary greatly between countries. With few exceptions, these are lower in East and Southeast Asian and Sub-Saharan African countries compared with other regions. Epidemiological differences may reflect differences in border closures, lockdowns, and social distancing measures taken by each county, and by cultural differences, such as common use of face masks in East and Southeast Asian countries. The plasma serine protease inhibitor alpha-1 antitrypsin was suggested to protect from COVID-19 by inhibiting TMPRSS2, a cell surface serine protease essential for the SARS-CoV-2 cell entry. Here, we present evidence that population differences in alpha-1 antitrypsin deficiency allele frequencies may partially explain national differences in the COVID-19 epidemiology. Our study compared reported national estimates for the major alpha-1 antitrypsin deficiency alleles PiZ and PiS (SERPINA1 rs28929474 and rs17580, respectively) with the Johns Hopkins University Coronavirus Resource Center dataset. We found a significant positive correlation (R = .54, P = 1.98e-6) between the combined frequencies of the alpha-1 antitrypsin PiZ and PiS deficiency alleles in 67 countries and their reported COVID-19 mortality rates. Our observations suggest that alpha-1 antitrypsin deficiency alleles may contribute to national differences in COVID-19 infection, severity, and mortality rates. Population-wide screening for carriers of alpha-1 antitrypsin deficiency alleles should be considered for prioritizing individuals for stricter social distancing measures and for receiving a SARS-CoV-2 vaccine once it becomes available.