Reported CCR5-∆32 deviation from Hardy-Weinberg equilibrium is explained by poor genotyping of rs62625034

In the fall of 2018, news broke about a researcher from China who had used CRISPR gene editing to cause human babies to have a deletion in the CCR5 chemokine receptor, making them resistant to HIV infection. One of the numerous ethical concerns about this study is that the deletion may have other effects. Subsequently, Nature Medicine published a Brief Communications from Wei and Nielsen concluding that homozygotes for the CCR5-∆32 deletion have a survival probability to age 76 of 83.5% compared to 86.5% and 86.4% for the heterozygotes and the other homozygote, respectively, and that observed departures from Hardy Weinberg proportions also support selection operating on this allele1. In the study, Wei and Nielsen used a proxy variant, rs62625034 in their analysis. Here, we report that the reported CCR5-∆32 deviation from Hardy-Weinberg equilibrium (HWE) inferred by Wei and Nielsen can be explained by poor genotyping of rs62625034, the variant used for their analysis.

Regulating G protein-coupled receptors by topological inversion

G protein-coupled receptors (GPCRs) are a family of proteins containing seven transmembrane helices, with the N- and C-terminus of the protein located at the extracellular space and cytosol, respectively. Here, we report that ceramide or related sphingolipids might invert the topology of many GPCRs that contain a GXXXN motif in their first transmembrane helix. The functional significance of this topological regulation is illustrated by the CCR5 chemokine receptor. In the absence of lipopolysaccharide (LPS), CCR5 adopts a topology consistent with that of GPCR, allowing mouse peritoneal macrophages to migrate toward its ligand CCL5. LPS stimulation results in increased production of dihydroceramide, which inverts the topology of CCR5, preventing macrophages from migrating toward CCL5. These results suggest that GPCRs may not always adopt the same topology and can be regulated through topological inversion.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that major issues remain unresolved (<xref ref-type="decision-letter" rid="SA1">see decision letter</xref>).

HIV-associated neurocognitive disorders: recent advances in pathogenesis, biomarkers, and treatment

HIV-associated neurocognitive disorders (HAND) remain prevalent despite plasma viral suppression by antiretroviral agents. In fact, the prevalence of milder subtypes of cognitive impairment is increasing. Neuropsychologic testing remains the “gold standard” of diagnosis; however, this is time consuming and costly in a resource-poor environment. Recently developed screening tools, such as CogState and the revised HIV dementia scale, have very good sensitivity and specificity in the more severe stages of HAND. However, questions remain regarding the utility of, optimal population for, and insensitivity of tests in mild HAND.Recognition of ongoing viral persistence and the inflammatory milieu in the central nervous system (CNS) has advanced our understanding of the pathogenesis of HAND and facilitated the development of biomarkers of CNS disease. The importance of the monocyte-macrophage lineage cell and the astrocyte as viral reservoirs, HIV viral proteins, self-perpetuating CNS inflammation, and CCR5 chemokine receptor neurotropism has been identified. Whilst biomarkers demonstrate monocyte activation, inflammation, and neuronal injury, they remain limited in their clinical utility. The improved understanding of pathogenic mechanisms has led to novel approaches to the treatment of HAND; however, despite these advances, the optimal management is still undefined.

Hypothesis about the protective role of ccr5delta32 mutations in juvenile idiopathic arthritis: fiction or reality?

It is suspected that the prevalence in different ethnic groups of HLA-genotype and of mutation CCR5delta32 - factors which alter adhesion of protein CCR5 - are the causes of different prevalence of juvenile idiopathic arthritis in different ethnic populations. Prerequisites to the fact that the mutation CCR5delta32 may have importance in determining susceptibility to the disease were the observations showing that CCR5 deletion polymorphism reveals a population and geographic diversity in addition to ethnic specificity. But reports on the role of gene deletion in the CCR5 chemokine receptor susceptibility to JIA rather contradictory. 234 DNA samples of patients with systemic JIA (soJIA) were ana-lyzed. The diagnosis was made according to the ILAR criteria. DNA was isolated using QIAamp Mini Kit (QIAGEN) according to the protocol provided. Our results didn’t reveal any differences in prevalence of mutation in patients with soJIA, in patients with soJIA + macrophage activation syndrome and in total population. Our results do not support the idea of protective role of the muta-tion CCR5delta32 against soJIA, which conclusion can be explained also by probable association of soJIA with HLA-genotype or other factors of ethnicity. At the same time, it can be considered as an additional evidence of expediency of soJIA being an original disease different from the rest of JIA group of diseases.