Introduction: The Dutch Pharmacogenetics Working Group (DPWG) indicated a list of actionable genotypes that affect patients’ response to more 50 drugs; these drugs which show variable effects based on patients’ genetic traits were named as pharmacogenetics (PGX) drugs. Preemptive genetic testing before using these drugs may protect certain patients from serious adverse reactions and could help in avoiding treatment failures. The objectives of this study include identifying the rate of PGX drug usage among Dutch population, estimating the level of users who carry the actionable genotypes and determining the main genes involved in drug’s effect variability. Methods; Usage of PGX drugs over 2011–2017 by the insured population (an average of 11.4 million) in outpatient clinics in Netherlands was obtained from the publically available GIP databank. The data of 45 drugs were analyzed and their interactions with selected pharmacogenes were estimated. Frequency of actionable genotypes of 249 Dutch parents was obtained from the public database: Genome of Netherlands (GoNL), to identify the pattern of genetic characteristics of Dutch population. Results: Over a 7 year period, 51.3 million exposures of patients to PGX drugs were reported with an average of 5.3 exposures per each drug user. One quarterof the exposures (12.4 million) are predicted to be experienced by individuals with actionable genotypes (risky exposures). Up to 60% of the risky exposures (around 7.5 million) were related to drugs metabolized by CYP2D6. SLCO1B1, and CYP2C19 were also identified among the top genes affecting response of drugs users (involved in about 22 and 12.4% of the risky exposures, respectively). Cardiovascular medications were the top prescribed PGX drug class (43%), followed by gastroenterology (29%) and psychiatry/neurology medications (15%). Women use more PGX drugs than men (55.8 vs. 44.2%, respectively) with the majority (84%) of users in both sexes are above 45 years. Conclusion: PGX drugs are commonly used in Netherlands. Preemptive panel testing for CYP2D6, SLCO1B1, and CYP2C19 only could be useful to predict 95% of vulnerable patients’ exposures to PGX drugs. Future studies to assess the economic impact of preemptive panel testing on patients of older age are suggested.

Background: Different levels of evidence related to the variable responses of individuals to drug treatment have been reported in various pharmacogenomic (PGx) databases. Identification of gene-drug pairs with strong association evidence can be helpful in prioritizing the implementation of PGx guidelines and focusing on a gene panel. This study aimed to determine the pharmacogenes with the highest evidence-based association and to indicate their involvement in drug-gene interactions.Methodology: The publicly available datasets CPIC, DPWG, and PharmGKB were selected to determine the pharmacogenes with the highest drug outcome associations. The upper two levels of evidence rated by the three scoring methods were specified (levels A–B in CPIC, 3–4 in DPWG, or 1–2 levels in PharmGKB). The identified pharmacogenes were further ranked in this study based on the number of medications they interacted with.Results: Fifty pharmacogenes, with high to moderately high evidence of associations with drug response alterations, with potential influence on the therapeutic and/or toxicity outcomes of 152 drugs were identified. CYP2D6, CYP2C9, CYP2C19, G6PD, HLA-B, SLCO1B1, CACNA1S, RYR1, MT-RNR1, and IFNL4 are the top 10 pharmacogenes, where each is predicted to impact patients' responses to ≥5 drugs.Conclusion: This study identified the most important pharmacogenes based on the highest-ranked association evidence and their frequency of involvement in affecting multiple drugs. The obtained data is useful for customizing a gene panel for PGx testing. Identifying the strength of scientific evidence supporting drug-gene interactions aids drug prescribers in making the best clinical decision.

Intellectual disability (ID) is a highly heterogeneous genetic condition with more than a thousand genes described so far. By exome sequencing of two consanguineous families presenting hallmark features of ID, we identified two homozygous variants in two genes previously associated with autosomal recessive ID: NDST1 (c.1966G>A; p.Asp656Asn) and METTL23 (c.310T>C; p.Phe104Leu). The segregation of the variants was validated by Sanger sequencing in all family members. In silico homology modeling of wild-type and mutated proteins revealed substantial changes in the secondary structure of both proteins, indicating a possible effect on function. The identification and validation of new pathogenic NDST1 and METTL23 variants in two cases of autosomal recessive ID further highlight the importance of these genes in proper brain function and development.

The liver is susceptible to drug toxicity due to its vital role in xenobiotic metabolism and elimination. In addition to human leukocyte antigen (HLA) variants, which were previously determined as risk factors for drug-induced liver injury (DILI) due to co-amoxiclav, other non-HLA genes may contribute to hepatotoxicity risk. In this study, the association between DILI due to co-amoxiclav and several non-HLA genes was investigated. Association of variants in candidate genes ( SOD2, GPX1, GSTM1, and GSTT1 ) with DILI due to various drugs was reported previously in other DILI cohorts. This study examined relevance in a co-amoxiclav-DILI cohort. One hundred sixty-five co-amoxiclav DILI cases were recruited from several European countries by two different studies (DILIGEN and iDILIC). A North-East England population group ( n = 334) was used as the control group. PCR assays were used to genotype for the GSTM1 and GSTT1 null alleles with TaqMan SNP genotyping assays used for SOD2 (rs4880) and GPX1 (rs1050450). Fisher's exact test was used to assess differences in significance between cases and controls. None of the studied variants ( SOD2 rs4880, GPX1 rs1050450, GSTM1 null allele, and GSTT1 null allele) was significantly associated with co-amoxiclav DILI compared with the control group. No significant differences between cases and controls were seen when combined SOD2/GPX1 genotypes and GST genotypes were considered. Despite the possible functional relevance and the previously reported contribution of the selected genes to DILI, our study failed to confirm associations between the selected genes and liver injury induced by co-amoxiclav.

Background: Sickle cell disease (SCD) is a Mendelian disease characterized by multigenic phenotypes. Previous reports indicated a higher rate of thromboembolic events (TEEs) in SCD patients. A number of candidate polymorphisms in certain genes (e.g., FVL, PRT, and MTHFR) were previously reported as risk factors for TEEs in different clinical conditions. This study aimed to genotype these genes and other loci predicted to underlie TEEs in SCD patients. Methodology: A multi-center genome-wide association study (GWAS) involving Saudi SCD adult patients with a history of TEEs (n = 65) and control patients without TEE history (n = 285) was performed. Genotyping used the 10× Affymetrix Axiom array, which includes 683,030 markers. Fisher’s exact test was used to generate p-values of TEE associations with each single-nucleotide polymorphism (SNP). The haplotype analysis software tool version 1.05, designed by the University of Göttingen, Germany, was used to identify the common inherited haplotypes. Results: No association was identified between the targeted single-nucleotide polymorphism rs1801133 in MTHFR and TEEs in SCD (p = 0.79). The allele frequency of rs6025 in FVL and rs1799963 in PRT in our cohort was extremely low (<0.01); thus, both variants were excluded from the analysis as no meaningful comparison was possible. In contrast, the GWAS analysis showed novel genome-wide associations (p < 5 × 10⁻⁸) with seven signals; five of them were located on Chr 11 (rs35390334, rs331532, rs317777, rs147062602, and rs372091), one SNP on Chr 20 (rs139341092), and another on Chr 9 (rs76076035). The other 34 SNPs located on known genes were also detected at a signal threshold of p < 5 × 10⁻⁶. Seven of the identified variants are located in olfactory receptor family 51 genes (OR51B5, OR51V1, OR51A1P, and OR51E2), and five variants were related to family 52 genes (OR52A5, OR52K1, OR52K2, and OR52T1P). The previously reported association between rs5006884-A in OR51B5 and fetal hemoglobin (HbF) levels was confirmed in our study, which showed significantly lower levels of HbF (p = 0.002) and less allele frequency (p = 0.003) in the TEE cases than in the controls. The assessment of the haplotype inheritance pattern involved the top ten significant markers with no LD (rs353988334, rs317777, rs14788626882, rs49188823, rs139349992, rs76076035, rs73395847, rs1368823, rs8888834548, and rs1455957). A haplotype analysis revealed significant associations between two haplotypes (a risk, TT-AA-del-AA-ins-CT-TT-CC-CC-AA, and a reverse protective, CC-GG-ins-GG-del-TT-CC-TT-GG-GG) and TEEs in SCD (p = 0.024, OR = 6.16, CI = 1.34–28.24, and p = 0.019, OR = 0.33, CI = 0.13–0.85, respectively). Conclusions: Seven markers showed novel genome-wide associations; two of them were exonic variants (rs317777 in OLFM5P and rs147062602 in OR51B5), and less significant associations (p < 5 × 10⁻⁶) were identified for 34 other variants in known genes with TEEs in SCD. Moreover, two 10-SNP common haplotypes were determined with contradictory effects. Further replication of these findings is needed.

Sickle cell disease (SCD) is a severe inherited blood disorder characterized by abnormal hemoglobin (HbS) that leads to varying degrees of severity, including chronic hemolysis, episodic vaso-occlusion, and damage to multiple organs, causing significant morbidity and mortality. While SCD is a monogenic disease, its complications are influenced by polygenic factors. SCD prevalence is notably high in regions including the Middle East, with Saudi Arabia reporting significant cases, particularly in the Eastern Province. Most genetic factors associated with SCD outcomes have been identified in populations predominantly from Africa or of African ancestry. This study aims to identify genetic variants that characterize Saudi SCD patients with the potential to influence disease outcomes in this population. A multicenter case-control genome-wide association study (GWAS) was conducted involving 350 adult Saudi SCD patients and 202 healthy controls. Participants were genotyped using the Affymetrix Axiom array, covering 683,030 markers. Rigorous quality control measures were applied to ensure data integrity. Fisher’s exact was used to identify genetic variants with a significant difference in allele frequency (p < 5 × 10⁻⁸). Functional annotations and regulatory functions of variants were determined using the Ensembl Variant Effect Predictor (VEP) and RegulomeDB databases. The GWAS identified numerous significant genetic variants characterizing SCD cases in the Saudi population. These variants, distributed across multiple chromosomes, were found in genes with known functional consequences. A substantial proportion of the markers were detected in the olfactory receptor cluster, TRIM family, and HBB locus genes. Many of the identified genes were reported in previous studies showing significant associations with various SCD outcomes, including hemoglobin regulation, inflammation, immune response, and vascular function. The findings highlight the genetic complexity underlying SCD and its clinical manifestations. The identified variants suggest potential molecular biomarkers and therapeutic targets, enhancing our understanding of the molecular basis of SCD in the Saudi population. This is the first genetic analysis characterizing SCD patients compared to healthy individuals, uncovering genetic markers that could serve as diagnostic biomarkers and therapeutic targets. Given the known molecular mechanisms of the detected genetic loci, these provide a foundation for precision medicine in SCD management, highlighting the need for further studies to validate these results and explore their clinical implications.