Genetic Modifiers Associated with Vaso-Occlusive Crises and Acute Pain Phenomena in Sickle Cell Disease: A Scoping Review.

Sickle cell disease (SCD) is a group of recessive diseases caused by the β sickling mutation of in homozygosity or in compound heterozygosity with other pathogenic mutations. Patients with severe SCD typically experience painful vaso-occlusive crises and other pain-related phenomena, including acute chest syndrome, priapism, dactylitis, avascular necrosis, and splenic sequestration and infarction. High variability of pain-related phenomena per SCD genotype indicates genetic disease modifiers (GDMs) as pathology determinants and, thus, as critical to prognosis, treatment choice, and therapy development. Articles likely holding genetic information for SCD pain phenomena were identified in PubMed and SCOPUS for article quality assessment and extraction of corresponding GDMs and observations indicative of development areas in our understanding of SCD GDMs. This process led to the initial selection of 183 articles matching the search terms, which, after two-step selection, resulted in the inclusion of 100 articles for content analysis and of significant findings for GDMs from 37 articles. Published data point to gender effects and to 51 GDM SNVs, deletions, and regions, including globin genes and significant overrepresentation of gene ontology pathways related, e.g., to oxidative stress, hypoxia, and regulation of blood pressure. Analyzed articles further pointed to additional candidate GDMs affecting SCD VOC and pain phenomena and to potential confounding factors for GWAS analyses. We found that despite the critical importance of VOC and pain phenomena for SCD pathology, corresponding clinically relevant genetic insights are held back by a shortage of large-scale, systematic multi-ethnic efforts, as undertaken by the INHERENT Network.