Elbay Aliyev

Ancestry-specific genetic mapping of transcriptome regulation is pivotal for understanding genome function, especially in underrepresented consanguineous populations. Here we characterized 1,882 Qatar Biobank participants, integrating blood RNA sequencing, whole-genome sequencing and phenotypic data across 45 clinically relevant traits. We cataloged ~7 million significant quantitative trait loci (QTLs), both short and structural variants, impacting gene expression, isoform usage, splicing and allele-specific expression, uncovering 1,379 novel eGenes. Fine-mapping resolved 29,953 high-confidence, independent causal loci including 24% previously unreported as well as those with effect alleles showing significant divergence across global populations, while 1,371 were absent from public databases. Leveraging elevated autozygosity, we found that causal variants are depleted from runs of homozygosity, consistent with purifying selection, while recent autozygosity increased the burden of homozygous regulatory variants. We identified QTLs with recessive deleterious effects on 10 Mendelian disease genes and homozygous QTLs causing extreme outlier expression in 66 genes including dosage-sensitive ones. Colocalization analysis revealed 58 causal variants acting on 20 clinically relevant phenotypes, implicating novel genes including ATP6V0B and RQCD1 in metabolic and blood disorders. These findings establish this QTL catalog as a valuable Middle Eastern resource for genome interpretation and genomic medicine.

Introduction Tandem repeats (TRs), including short tandem repeats (1-6 bp motifs) and variable number tandem repeats (7+ bp motifs), have been linked to more than 50 Mendelian diseases. However, current frameworks for evaluating gene-disease relationships do not adequately address TR-specific complexities. As a result, proposed TR locus-disease relationships are often incorrectly classified, under-evaluated, or excluded entirely, limiting discovery and leading to underdiagnosis of TR disorders. Methods We developed criTRia, a scoring framework designed to accurately evaluate TR locus-disease relationships at the locus level rather than the gene level. Building on ClinGen best practices, criTRia introduces TR-specific evidence categories and reweighted scoring. We applied criTRia to curate 65 loci from STRchive, a database of disease-associated TRs. Results We compared criTRia curations with gene-level curations from nine Gene Curation Coalition (GenCC) groups. Of 65 newly scored loci, 7 had not been previously evaluated by GenCC and 17 showed significant disagreement across groups. These differences have direct implications for whether a disease is recommended for inclusion in a diagnostic gene panel. The criTRia framework also enabled curation of previously unassessed associations, bringing the total to 77 curated TR locus-disease associations and identifying four contradictory associations. Discussion By incorporating TR-specific evidence, criTRia provides a reproducible methodology for assessing TR locus-disease relationships, improving classification consistency and establishing a foundation for better integrating tandem repeats into clinical genetic medicine and providing more accurate diagnoses.

Background: Tandem repeats (TRs) play critical roles in human disease and phenotypic diversity but are among the most challenging classes of genomic variation to measure accurately. While it is possible to identify TR expansions using short-read sequencing, these methods are limited because they often cannot accurately determine repeat length or sequence composition. Long-read sequencing (LRS) has the potential to accurately characterize long TRs, including the identification of non-canonical motifs and complex structures. However, while there are an increasing number of genotyping methods available, no systematic effort has been undertaken to evaluate their length and sequence-level accuracy, performance across motifs from STRs to VNTRs and across allele lengths, and, critically, how usable these tools are in practice. Results: We reviewed 25 available bioinformatic tools, and selected seven that are actively maintained for benchmarking using publicly available Oxford Nanopore genome sequencing data from more than 100 individuals. Our benchmarking catalog included ∼43k TR loci genome-wide, selected to represent a range of simple and challenging TR loci. As no “truth” exists for this purpose, we used four complementary strategies to assess accuracy: concordance with high-quality haplotype-resolved Human Pangenome Reference Consortium (HPRC) assemblies, Mendelian consistency in Genome in a Bottle trios, cross-tool consistency, and sensitivity in individuals with pathogenic TR expansions confirmed by molecular methods. For all comparisons, we assess both total allele length and full sequence similarity using the Levenshtein distance. We also evaluated installation, documentation, computational requirements, and output characteristics to reflect real-world use. We provide a complete analysis workflow for all tools to support community reuse. Tool performance varied substantially across both accuracy and usability. Most methods achieved high concordance with HPRC assemblies, with higher accuracy when using the R10 ONT pore chemistry. Accuracy generally declined with increasing allele length, and most tools performed worse on homopolymers, likely reflecting underlying sequencing accuracy. Tools generally performed worse at heterozygous loci and at alleles that differed from the reference genome. Interestingly, concordance with assembly in population samples did not predict sensitivity to pathogenic expansions, with different genotypers performing best in each category. Similarly, Mendelian consistency was highest in the tool that performed worst in assembly concordance. Conclusions: No single genotyper emerged as consistently best across all assessments, but strong contenders emerged in each. Our results demonstrate that length accuracy (a typical benchmarking approach) alone overestimates TR genotyping performance. Sequence-level benchmarking is essential for selecting tools best-suited for population studies and clinical diagnostics. This work provides practical guidance for tool selection and highlights key priorities for future long-read TR genotyping method development.

We present a large-scale study of structural variation (SV) in the Qatari population, based on short-read whole-genome sequencing (WGS) of 6,141 individuals, identifying 153,946 variants across 5 classes reflecting the region’s diversity and evolutionary history. Leveraging consanguinity and biobank phenotypes, we identify >180 putative gene knockouts, and use proteomics to show functional consequences in homozygotes. Conversely, 52 genes show significant depletion of homozygous deletions, eight of which cause severe pediatric disease or murine embryonic lethality. Examining phenotypic extremes uncovers several non-exonic homozygous deletions with large effect, including in SPIRE2 (creatinine), MAGI2 (leanness) and a chr19 microRNA cluster (extreme obesity). Further, SV-GWAS reveals gene-trait associations independent of SNPs, including at ACY1 (acetylation), SLC2A9 (uric acid), UGT1A8 (bilirubin) and ZNF251 (alanine aminotransferase). Notably, 3.2% of Qataris carry findings in medically actionable genes, one-third attributable to SVs. Our findings offer a rich SV reference for a globally understudied population, and demonstrate the utility of consanguineous biobanks for studying SVs in health and disease. All common SVs and tag-SNPs are provided as imputation resource.

Ritscher-Schinzel syndrome (RSS) is a congenital malformation syndrome characterized by cerebellar, cardiac, and craniofacial malformations and phenotypes associated with liver, skeletal, and kidney dysfunction. The genetic cause of RSS remains to be fully defined, and limited information is available regarding the root cause of the multiple tissue phenotypes. Causative mutations in the Commander multiprotein assembly are an emerging feature of this syndrome. Commander organizes the sorting nexin-17 (SNX17)–dependent recycling of hundreds of integral membrane proteins through the endosomal network. Here, we identify previously unrecognized cohorts of patients with RSS that we genetically and clinically analyzed to identify causative genes in the copper metabolic murr1 domain–containing (COMMD) proteins COMMD4, COMMD9, and coiled-coil domain containing 93 (CCDC93) subunits of the Commander complex. Using interactome analysis, we determined that these mutations disrupted Commander assembly and, through cell surface proteomics, that this reduces tissue-specific presentation of cell surface integral membrane proteins essential for kidney, bone, and brain development. We established that these integral proteins contained ΦxNPxY/F or ΦxNxxY/F sorting motifs in their cytoplasmic-facing domains (where Φ is a hydrophobic residue and x is any residue) that are recognized by SNX17 to drive their Commander-dependent endosomal recycling. Last, through generation of mouse models of RSS, we show replication of RSS-associated clinical phenotypes including proteinuria, skeletal malformation, and neurological impairment. Our data establish RSS as a “recyclinopathy” that arises from a dysfunction in the Commander endosomal recycling pathway.

Pontocerebellar hypoplasia (PCH) encompasses a group of autosomal recessive neurodegenerative disorders marked by cerebellar and pontine atrophy. Multiple subtypes of PCH have been identified, among which the rare subtype PCH type 16 is caused by MINPP1 genetic variants. MINPPI encodes an enzyme essential for inositol polyphosphate dephosphorylation, regulating calcium and iron homeostasis. We conducted genome sequencing on a proband from the consanguineous family, who presented with a severe neurodegenerative disorder, to identify the underlying cause of disease. A comprehensive clinical assessment in addition to neuroradiological findings are described. We performed the functional validation of the identified variant and conducted untargeted metabolomic analyses. The clinical and radiological assessment of the patient showed a congenital brain anomaly and neurodegenerative symptoms. Further genetic analysis identified a homozygous loss-of-function variant (c.1401del, p.Ser468Valfs10*) in MINPP1, providing molecular confirmation of a clinical PCH diagnosis. While real-time quantitative PCR (RT-qPCR) showed that MINPP1 gene expression was unaffected in the proband, Western blot analysis demonstrated reduced protein abundance, supporting a pathogenic role of the variant. Metabolomic profiling revealed elevated lipid levels and disrupted inositol metabolism, providing further insights into the disease mechanism. These findings establish the pathogenicity of the p.Ser468Valfs10* variant in MINPP1 and highlight inositol metabolism as a potential pathway involved in PCH16, advancing the understanding of the pathophysiology of the disease.

Advances in long-read sequencing have enabled routine complete assembly of human genomes, but much remains to be done to represent broader populations and show impact on disease-gene discovery. Here, we report highly accurate, near-complete and phased genomes from six Middle Eastern (ME) family trios (n = 18) with neurodevelopmental conditions, representing ancestries from Sudan, Jordan, Syria, Qatar and Afghanistan. These genomes revealed 42.2 Mb of new sequence (13.8% impacting known genes), 75 new HLA/KIR alleles and strong signals of inbreeding, with ROH covering up to one-third of chromosomes 6 and 12 in one individual. Using assembly-based variant calling, we identified 23 de novo and recessive variants as strong candidates for causing previously unresolved symptoms in the probands. The ME genomes revealed unique variation relative to existing references, showing enhanced mappability and variant calling. These results underscore the value of de novo assembly for disease variant discovery and the need for sampled ME-specific references to better characterize population-relevant variation.

Leveraging whole genome sequencing data of 1751 individuals from the UK and 2587 Qatari subjects, we suggest here an association of rare variants mapping to the sour taste-associated gene KCNJ2 with reduced low-density lipoprotein cholesterol (LDL-C, P = 2.10 × 10⁻¹²) and with a 22% decreased dietary trans-fat intake. This study identifies a novel candidate rare locus for LDL-C, adding insights into the genetic architecture of a complex trait implicated in cardiovascular disease.

Clefts of the lip and/or palate (CL/P) are considered the most common form of congenital anomalies occurring either in isolation or in association with other clinical features. Van der woude syndrome (VWS) is associated with about 2% of all CL/P cases and is further characterized by having lower lip pits. Popliteal pterygium syndrome (PPS) is a more severe form of VWS, normally characterized by orofacial clefts, lower lip pits, skin webbing, skeletal anomalies and syndactyly of toes and fingers. Both syndromes are inherited in an autosomal dominant manner, usually caused by heterozygous mutations in the Interferon Regulatory Factor 6 (IRF6) gene. Here we report the case of a two-generation family where the index presented with popliteal pterygium syndrome while both the father and sister had clinical features of van der woude syndrome, but without any point mutations detected by re-sequencing of known gene panels or microarray testing. Using whole genome sequencing (WGS) followed by local de novo assembly, we discover and validate a copy-neutral, 429 kb complex intra-chromosomal rearrangement in the long arm of chromosome 1, disrupting the IRF6 gene. This variant is copy-neutral, novel against publicly available databases, and segregates in the family in an autosomal dominant pattern. This finding suggests that missing heritability in rare diseases may be due to complex genomic rearrangements that can be resolved by WGS and de novo assembly, helping deliver answers to patients where no genetic etiology was identified by other means.

In October 2021, 59 scientists from 14 countries and 13 U.S. states collaborated virtually in the Third Annual Baylor College of Medicine & DNANexus Structural Variation hackathon. The goal of the hackathon was to advance research on structural variants (SVs) by prototyping and iterating on open-source software. This led to nine hackathon projects focused on diverse genomics research interests, including various SV discovery and genotyping methods, SV sequence reconstruction, and clinically relevant structural variation, including SARS-CoV-2 variants. Repositories for the projects that participated in the hackathon are available at https://github.com/collaborativebioinformatics.