The APOBEC/AID family is known for its mutator activity, and recent evidence also supports the potential impact of ADARs. Furthermore, the mutator impacts of APOBEC/ADAR mutations have not yet been investigated. Assessment of pancancer TCGA exomes identified enriched somatic variants among exomes with nonsynonymous APOBEC1, APOBEC3B, APOBEC3C, ADAR, and ADARB1 mutations, compared to exomes with synonymous ones. Principal component (PC) analysis reduced the number of potential players to eight in cancer exomes/genomes, and to five in cancer types. Multivariate regression analysis was used to assess the impact of the PCs on each COSMIC mutational signature among pancancer exomes/genomes and particular cancers, identifying several novel links, including SBS17b, SBS18, and ID7 mainly determined by APOBEC1 mRNA levels; SBS40, ID1, and ID2 by age; SBS3 and SBS16 by APOBEC3A/APOBEC3B mRNA levels; ID5 and DBS9 by DNA repair/replication (DRR) defects; and SBS7a-d, SBS38, ID4, ID8, ID13, and DBS1 by ultraviolet (UV) radiation/ADARB1 mRNA levels. APOBEC/ADAR mutations appeared to potentiate the impact of DRR defects on several mutational signatures, and some factors seemed to inversely affect certain signatures. These findings potentially implicate certain APOBEC/ADAR mutations/mRNA levels in distinct mutational signatures, particularly APOBEC1 mRNA levels in aging-related signatures and ADARB1 mRNA levels in UV radiation-related signatures.

BACKGROUND: Inherited retinal dystrophies (IRD) are one of the main causes of incurable blindness worldwide. IRD are caused by mutations in genes that encode essential proteins for the retina, leading to photoreceptor degeneration and loss of visual function. IRD generates an enormous global financial burden due to the lack of understanding of a significant part of its pathophysiology, molecular diagnosis, and the near absence of non-palliative treatment options. Patient-derived induced pluripotent stem cells (iPSC) for IRD seem to be an excellent option for addressing these questions, serving as exceptional tools for in-depth studies of IRD pathophysiology and testing new therapeutic approaches.
METHODS: From a cohort of 8 patients with PROM1-related IRD, we identified 3 patients carrying the same variant (c.1354dupT) but expressing three different IRD phenotypes: Cone and rod dystrophy (CORD), Retinitis pigmentosa (RP), and Stargardt disease type 4 (STGD4). These three target patients, along with one healthy relative from each, underwent comprehensive ophthalmic examinations and their genetic panel study was expanded through clinical exome sequencing (CES). Subsequently, non-integrative patient-derived iPSC were generated and fully characterized. Correction of the c.1354dupT mutation was performed using CRISPR/Cas9, and the genetic restoration of the PROM1 gene was confirmed through flow cytometry and western blotting in the patient-derived iPSC lines.
RESULTS: CES revealed that 2 target patients with the c.1354dupT mutation presented monoallelic variants in genes associated with the complement system or photoreceptor differentiation and peroxisome biogenesis disorders, respectively. The pluripotency and functionality of the patient-derived iPSC lines were confirmed, and the correction of the target mutation fully restored the capability of encoding Prominin-1 (CD133) in the genetically repaired patient-derived iPSC lines.
CONCLUSIONS: The c.1354dupT mutation in the PROM1 gene is associated to three distinct AR phenotypes of IRD. This pleotropic effect might be related to the influence of monoallelic variants in other genes associated with retinal dystrophies. However, further evidence needs to be provided. Future experiments should include gene-edited patient-derived iPSC due to its potential as disease modelling tools to elucidate this matter in question.

Molecular diagnosis of inborn errors of immunity (IEI) plays a critical role in determining patients\' long-term prognosis, treatment options, and genetic counseling. Over the past decade, the broader utilization of next-generation sequencing (NGS) techniques in both research and clinical settings has facilitated the evaluation of a significant proportion of patients for gene variants associated with IEI. In addition to its role in diagnosing known gene defects, the application of high-throughput techniques such as targeted, exome, and genome sequencing has led to the identification of novel disease-causing genes. However, the results obtained from these different methods can vary depending on disease phenotypes or patient characteristics. In this study, we conducted whole-exome sequencing (WES) in a sizable cohort of IEI patients, consisting of 303 individuals from 21 different clinical immunology centers in Türkiye. Our analysis resulted in likely genetic diagnoses for 41.1% of the patients (122 out of 297), revealing 52 novel variants and uncovering potential new IEI genes in six patients. The significance of understanding outcomes across various IEI cohorts cannot be overstated, and we believe that our findings will make a valuable contribution to the existing literature and foster collaborative research between clinicians and basic science researchers.

The tyrosine kinase Inhibitor (TKI) imatinib is approved for the treatment of the chronic phase of chronic myeloid leukemia (CP-CML). Pharmacokinetic studies have highlighted the importance of inter-patient variability on imatinib plasma trough concentrations (ima[C]min). In the OPTIM-imatinib trial, we demonstrated that therapeutic drug monitoring (TDM) is able to improve the molecular response of CP-CML patients treated with imatinib. Here, we analyzed the constitutional exomes and RNAseq data of these patients. We performed an association analysis between the constitutional genetic variants of the patients and their ima[C]min, measured after 12 weeks of treatment with 400 mg once daily. Using linear regression, we identified 50 SNPs that showed excess heterozygosity depending on the ima[C]min. Ten SNPs were from non-coding sequences, and among the 40 remaining, 30 (from 25 genes) could be split into two categories. The first group of 16 SNPs concerns genes encoding extracellular matrix, cell junction, and membrane proteins. Coincidentally, cell adhesion proteins were also identified by RNA-seq as being overexpressed in patients with high ima[C]min. The other group of 14 SNPs were from genes encoding proteins involved in transcription/translation. Although most of the SNPs are intronic variants (28), we also identified missense (3), synonymous (4), 5\'/3\' (2), splicing (1), and upstream (4) variants. A haplotype analysis of four genes showed a significant association with high ima[C]min. None of the SNPs were significantly associated with the response. In conclusion, we identified a number of ima[C]min-associated SNPs, most of which correspond to genes encoding proteins that could play a role in the diffusion and transit of imatinib through membranes or epithelial barriers.

Hereditary spastic paraplegias are a diverse group of degenerative disorders that are clinically categorized as isolated; with involvement of lower limb spasticity, or symptomatic, where spastic paraplegia is complicated by further neurological features. We sought to identify the underlying genetic causes of these disorders in the participating patients. Three consanguineous families with multiple affected members were identified by visiting special schools in the Punjab Province. DNA was extracted from blood samples of the participants. Exome sequencing was performed for selected patients from the three families, and the data were filtered to identify rare homozygous variants. ExomeDepth was used for the delineation of the copy number variants. All patients had varying degrees of intellectual disabilities, poor speech development, spasticity, a wide-based gait or an inability to walk and hypertonia. In family RDHR07, a homozygous deletion involving multiple exons and introns of SPG11 (NC000015.9:g.44894055_449028del) was found and correlated with the phenotype of the patients who had spasticity and other complex movement disorders, but not those who exhibited ataxic or indeterminate symptoms as well. In families ANMD03 and RDFA06, a nonsense variant, c.985C > T;(p.Arg329Ter) in DDHD2 and a frameshift insertion‒deletion variant of AP4B1, c.965-967delACTinsC;p.(Tyr322SerfsTer14), were identified which were homozygous in the patients while the obligate carriers in the respective pedigrees were heterozygous. All variants were ultra-rare with none, or very few carriers identified in the public databases. The three loss of function variants are likely to cause nonsense-mediated decay of the respective transcripts. Our research adds to the genetic variability associated with the SPG11 and AP4B1 variants and emphasizes the genetic heterogeneity of hereditary spastic paraplegia.

Mosaic loss of the X chromosome (mLOX) is the most common clonal somatic alteration in leukocytes of female individuals1,2, but little is known about its genetic determinants or phenotypic consequences. Here, to address this, we used data from 883,574 female participants across 8 biobanks; 12% of participants exhibited detectable mLOX in approximately 2% of leukocytes. Female participants with mLOX had an increased risk of myeloid and lymphoid leukaemias. Genetic analyses identified 56 common variants associated with mLOX, implicating genes with roles in chromosomal missegregation, cancer predisposition and autoimmune diseases. Exome-sequence analyses identified rare missense variants in FBXO10 that confer a twofold increased risk of mLOX. Only a small fraction of associations was shared with mosaic Y chromosome loss, suggesting that distinct biological processes drive formation and clonal expansion of sex chromosome missegregation. Allelic shift analyses identified X chromosome alleles that are preferentially retained in mLOX, demonstrating variation at many loci under cellular selection. A polygenic score including 44 allelic shift loci correctly inferred the retained X chromosomes in 80.7% of mLOX cases in the top decile. Our results support a model in which germline variants predispose female individuals to acquiring mLOX, with the allelic content of the X chromosome possibly shaping the magnitude of clonal expansion.

BACKGROUND: Genetic variants that cause rare disorders may remain elusive even after expansive testing, such as exome sequencing. The diagnostic yield of genome sequencing, particularly after a negative evaluation, remains poorly defined.
METHODS: We sequenced and analyzed the genomes of families with diverse phenotypes who were suspected to have a rare monogenic disease and for whom genetic testing had not revealed a diagnosis, as well as the genomes of a replication cohort at an independent clinical center.
RESULTS: We sequenced the genomes of 822 families (744 in the initial cohort and 78 in the replication cohort) and made a molecular diagnosis in 218 of 744 families (29.3%). Of the 218 families, 61 (28.0%) - 8.2% of families in the initial cohort - had variants that required genome sequencing for identification, including coding variants, intronic variants, small structural variants, copy-neutral inversions, complex rearrangements, and tandem repeat expansions. Most families in which a molecular diagnosis was made after previous nondiagnostic exome sequencing (63.5%) had variants that could be detected by reanalysis of the exome-sequence data (53.4%) or by additional analytic methods, such as copy-number variant calling, to exome-sequence data (10.8%). We obtained similar results in the replication cohort: in 33% of the families in which a molecular diagnosis was made, or 8% of the cohort, genome sequencing was required, which showed the applicability of these findings to both research and clinical environments.
CONCLUSIONS: The diagnostic yield of genome sequencing in a large, diverse research cohort and in a small clinical cohort of persons who had previously undergone genetic testing was approximately 8% and included several types of pathogenic variation that had not previously been detected by means of exome sequencing or other techniques. (Funded by the National Human Genome Research Institute and others.).

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Radiotherapy is focused on the tumor but also reaches healthy tissues, causing toxicities that are possibly related to genomic factors. In this context, radiogenomics can help reduce the toxicity, increase the effectiveness of radiotherapy, and personalize treatment. It is important to consider the genomic profiles of populations not yet studied in radiogenomics, such as the indigenous Amazonian population. Thus, our objective was to analyze important genes for radiogenomics, such as ATM, TGFB1, RAD51, AREG, XRCC4, CDK1, MEG3, PRKCE, TANC1, and KDR, in indigenous people and draw a radiogenomic profile of this population. The NextSeq 500® platform was used for sequencing reactions; for differences in the allelic frequency between populations, Fisher\'s Exact Test was used. We identified 39 variants, 2 of which were high impact: 1 in KDR (rs41452948) and another in XRCC4 (rs1805377). We found four modifying variants not yet described in the literature in PRKCE. We did not find any variants in TANC1-an important gene for personalized medicine in radiotherapy-that were associated with toxicities in previous cohorts, configuring a protective factor for indigenous people. We identified four SNVs (rs664143, rs1801516, rs1870377, rs1800470) that were associated with toxicity in previous studies. Knowing the radiogenomic profile of indigenous people can help personalize their radiotherapy.

Large-scale genomic studies have significantly increased our knowledge of genetic variability across populations. Regional genetic profiling is essential for distinguishing common benign variants from disease-causing ones. To this end, we conducted a comprehensive characterization of exonic variants in the population of Navarre (Spain), utilizing whole genome sequencing data from 358 unrelated individuals of Spanish origin. Our analysis revealed 61,410 biallelic single nucleotide variants (SNV) within the Navarrese cohort, with 35% classified as common (MAF > 1%). By comparing allele frequency data from 1000 Genome Project (excluding the Iberian cohort of Spain, IBS), Genome Aggregation Database, and a Spanish cohort (including IBS individuals and data from Medical Genome Project), we identified 1069 SNVs common in Navarre but rare (MAF ≤ 1%) in all other populations. We further corroborated this observation with a second regional cohort of 239 unrelated exomes, which confirmed 676 of the 1069 SNVs as common in Navarre. In conclusion, this study highlights the importance of population-specific characterization of genetic variation to improve allele frequency filtering in sequencing data analysis to identify disease-causing variants.