Biomedical subjects

Victoria Nembaware

Publications and source records attributed to Victoria Nembaware.

4 recordsLinked to original sources

PubMed2025

Clinical and Genetic Predictors of Sickle Cell Nephropathy: A Global Systematic Review.

Sickle cell disease (SCD) affects nearly 300,000 newborns annually worldwide, with 80% born in Africa. Sickle cell nephropathy (SCN) affects 5-18% of patients with SCD and contributes significantly to morbidity and mortality. Identifying SCN-associated factors would promote effective clinical management. We conducted a global systematic review in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines (Prospective Register of Systematic Reviews, registration number: CRD42020185763) to explore clinical and genetic correlates of SCN. We sought after cohort, case-control, and cross-sectional studies published up to December 31, 2024 that reported on clinical and/or genetic predictors of SCN in different populations globally. A total of 70 hospital-based study articles were finally included, with a leading percentage (45.7%) of the included studies performed in the United States, whereas 24.3% were from Sub-Saharan Africa. Most had a cross-sectional design (68.6%) involving children and adults. Genetic studies (17/70) identified associations with α-thalassemia, APOL1, and HMOX1 genes. The only genome-wide association study identified six suggestive variants in CRYL1, VWF, ADAMTS7, LRP1B, linc02288, and FPGT-TNNI3K/TNNI3K among adult patients. In conclusion, this systematic review (1) unpacks and highlights the role of clinical, genetic, and biochemical factors in the pathogenesis and progression of SCN and (2) reveals the consistent association of SCN with the 3.7 Kb deletion in HBA and variants in APOL1 and HMOX1 genes. This systematic review underscores the paucity of data from Africa, emphasizing the need for large-scale prospective studies on African SCN cohorts. Our findings also provide a foundation for the early identification of individuals at risk for SCN and the avenues for clinical and public health management strategies. To the best of our knowledge, this is the first systematic review summarizing risk factors for kidney dysfunction in SCD populations worldwide, which includes, specifically, a meta-analysis for APOL1 association with albuminuria.

Humans↗

PubMed2004

Allele-specific transcript isoforms in human.

Estimates of the number of human genes that produce more than one transcript isoform through alternative mRNA splicing depend on the assumption that the observation of multiple transcripts from a gene can be attributed entirely to alternative splicing. It is possible, however, that a substantial proportion of cases where multiple transcripts have been observed for a gene result from differences between alleles. Many examples of genes that are spliced differently from different alleles have been reported but no systematic estimate of the proportion of alternatively spliced genes that are affected by such polymorphisms has been carried out. We find that alternative transcript isoforms are non-randomly associated with closely linked nucleotide polymorphisms, based on an integrated analysis of the dbSNP, dbEST and ASAP databases. From the observed level of association between transcript isoforms and polymorphisms, we estimate that 21% of alternatively spliced genes are affected by polymorphisms that either completely determine which form of the transcript is observed or alter the relative abundances of some of the alternative isoforms. We provide a conservative lower bound of 6% on this estimate and point out that alternative splicing cannot be confirmed absolutely unless more than one transcript is observed from the same allele.

Alleles↗

PubMed2004

A plant natriuretic peptide-like gene in the bacterial pathogen Xanthomonas axonopodis may induce hyper-hydration in the plant host: a hypothesis of molecular mimicry.

BACKGROUND: Plant natriuretic peptides (PNPs) are systemically mobile molecules that regulate homeostasis at nanomolar concentrations. PNPs are up-regulated under conditions of osmotic stress and PNP-dependent processes include changes in ion transport and increases of H2O uptake into protoplasts and whole tissue. PRESENTATION OF THE HYPOTHESIS: The bacterial citrus pathogen Xanthomonas axonopodis pv. Citri str. 306 contains a gene encoding a PNP-like protein. We hypothesise that this bacterial protein can alter plant cell homeostasis and thus is likely to represent an example of molecular mimicry that enables the pathogen to manipulate plant responses in order to bring about conditions favourable to the pathogen such as the induced plant tissue hyper-hydration seen in the wet edged lesions associated with Xanthomonas axonopodis infection. TESTING THE HYPOTHESIS: We found a Xanthomonas axonopodis PNP-like protein that shares significant sequence similarity and identical domain organisation with PNPs. We also observed a significant excess of conserved residues between the two proteins within the domain previously identified as being sufficient to induce biological activity. Structural modelling predicts identical six stranded double-psi beta barrel folds for both proteins thus supporting the hypothesis of similar modes of action. No significant similarity between the Xanthomonas axonopodis protein and other bacterial proteins from GenBank was found. Sequence similarity of the Xanthomonas axonopodis PNP-like protein with the Arabidopsis thaliana PNP (AtPNP-A), shared domain organisation and incongruent phylogeny suggest that the PNP-gene may have been acquired by the bacteria in an ancient lateral gene transfer event. Finally, activity of a recombinant Xanthomonas axonopodis protein in plant tissue and changes in symptoms induced by a Xanthomonas axonopodis mutant with a knocked-out PNP-like gene will be experimental proof of molecular mimicry. IMPLICATION OF THE HYPOTHESIS: If the hypothesis is true, it could at least in part explain why the citrus pathogen Xanthomonas campestris that does not contain a PNP-like gene produces dry corky lesions while the closely related Xanthomonas axonopodis forms lesions with wet edges. It also suggests that genes typically found in the host, horizontally transferred or heterologous, can help to explain aspects of the physiology of the host-pathogen interactions.

Amino Acid Sequence↗

PubMed2002

Impact of the presence of paralogs on sequence divergence in a set of mouse-human orthologs.

Using a large set of orthologous human and mouse gene pairs, we have characterized genes that have been retained in duplicate in human over timescales comparable to the time of speciation of human and mouse. Orthologous gene pairs for which a paralogous gene has been present for much or all of the time since speciation show an increased rate of nonsynonymous substitution. We have related rate of divergence to functional classification using the Gene Ontology terms. Protein function was found, in some cases, to have a larger impact on rate of evolution than the presence or absence of a paralog. No evidence was found that genes that have been retained in duplicate are weighted toward any functional categories. An increase in the ratio of nonsynonymous to synonymous changes following duplication has previously been reported. However, because amino acid sequences include conservative as well as more freely evolving sites, the ratio of nonsynonymous to synonymous changes tends to be higher for closely related pairs. By measuring the divergence of orthologs only and comparing between genes for which a paralogous gene is either present or absent, we have compared gene pairs that share a common divergence time. We have also found that shorter genes have a higher probability of being found duplicated in the human genome, possibly reflecting a mutational effect.

Alleles↗