Project description:Several RHCE*ce alleles have in common a 733C>G (Leu245Val) change. Some encode an altered expression of e on red blood cells (RBCs) and individuals with such RBCs can make e-like alloantibodies. The identification of an apparent anti-hr(B) in the serum of an E-e+ African American patient prompted us to analyze her DNA, which revealed a novel RHCE*ce allele. We also screened blood samples from African Americans to determine the frequency of the novel allele.Hemagglutination tests and molecular analyses were performed by standard procedures.Analysis of the proband's DNA revealed RHCE*ce 48C/C, 733G/G, 941T/C, and 1006G/T. Of 272 samples from African Americans, 257 were RHCE*941T/T (wild type), and 15 (6%) were RHCE*941T/C. Of these 15, 14 were RHCE*ce/ce, 10 with 733C/G and four with 733G/G, and one was RHCE*ce/cE, 733C/G. Cloning experiments confirmed the Nucleotide 941 change and showed that 48C, 733G, 941C, and 1006T were carried on the same allele. RBCs from the 15 samples carrying the RHCE*941C variant typed V/VS+ and hrB+W.This study identifies a novel allele, RHCE*ce 48C, 733G, 941C, 1006T which is predicted to encode 16Cys, 245Val, 314Ala, and 336CyS and was shown to encode c, V/VS, and an altered expression of e and hrB antigens. The clinical significance of the antibody found in the proband is not established because E+e- RBC components were transfused to the patient. The novel RHCE*ce 48C, 733G, 941C, 1006T allele was present in 5.5% of samples from African Americans and thus, in this small cohort, it had a frequency of 0.028.
Project description:Immunohematology laboratories are regularly facing transfusion issues due to serological weaknesses. Altered (partial) RH antigens account for most of them. In some situations, RHCE variant alleles are involved. Herein we present our three-step molecular exploration, with allele frequencies, that has efficiently untangled RH2 phenotype weaknesses and discrepancies in our 2017-2021 cohort. In the last 5 years, the PACA Corse EFS molecular platform received 265 samples from healthy blood donors or patients with C and C/e typing difficulties. The first-intention technique (DNA array and real time PCR for RHCE*CeRN research) detected RHCE variant alleles in 143 cases (54%). The RHCE alleles classically found in African populations were the most frequent, with RHCE*CeRN allele in 40 cases (15%) and (C)ces haplotype type 1 and 2 in 26 cases (10%). A "CE" effect haplotype was suspected in 56 cases, due to the uncommon DCE haplotype that may explain the low C expression. When there were no RHCE*Ce or RHCE*CE alleles, we then searched for RHD polymorphisms by DNA array. We detected the RHD*DAU5 and RHD*DIVa in 18 and 7 cases respectively, suggesting that C ambiguity is related to the presence of these alleles which has never been described with DAU5. If no variant RHCE and RHD alleles were detected, we finally sequenced the 10 exons of both RHCE and RHD genes according to the clinical context and found seven new RHCE alleles. Thus, this molecular strategy would improve the knowledge of RHCE variants' expression and, thus, optimize the transfusion management.
Project description:Hematopoiesis is a complicated and dynamic process about which the molecular mechanisms remain poorly understood. Danio rerio (zebrafish) is an excellent vertebrate system for studying hematopoiesis and developmental mechanisms. In the previous study, we isolated and identified a cloche(172) (clo(172)) mutant, a novel allele compared to the original cloche (clo) mutant, through using complementation test and initial mapping. Here, according to whole mount in-situ hybridization, we report that the endothelial cells in clo(172) mutant embryos, although initially developed, failed to form the functional vascular system eventually. In addition, further characterization indicates that the clo(172) mutant exhibited weaker defects instead of completely lost in primitive erythroid cells and definitive hematopoietic cells compared with the clo(s5) mutant. In contrast, primitive myeloid cells were totally lost in clo(172) mutant. Furthermore, these reappeared definitive myeloid cells were demonstrated to initiate from the remaining hematopoietic stem cells (HSCs) in clo(172) mutant, confirmed by the dramatic decrease of lyc in clo(172)runx1(w84x) double mutant. Collectively, the clo(172) mutant is a weak allele compared to the clo(s5) mutant, therefore providing a model for studying the early development of hematopoietic and vascular system, as well as an opportunity to further understand the function of the cloche gene.
Project description:Rice fragrance is an important characteristic for Southeast Asian consumers, and fragrant landraces from Japan were first recorded in the 17th century. Principal component analysis clearly showed that Japanese fragrant landraces were genetically different from non-Japanese fragrant landraces. Japanese fragrant landraces were composed of six clades, none of which carried the most common fragrance mutation, an 8-bp deletion in exon 7 of Badh2. Fragrant landraces comprised two major groups carrying different Badh2 mutations. One group carried a known SNP at exon13 and the other a SNP at the exon1-intron1 junction as splicing donor site. The latter was considered to be a potential splicing mutant group as a novel allele at Badh2. Heterozygosity (He) scores in the two fragrant groups were not significantly different from non-fragrant landraces and modern cultivars. However, lower He scores were found around the Badh2 locus in the two groups. The potential splicing mutant group showed a more extended haplotype than the E13 SNP group. A likely causal factor responsible for loss of function is a novel splicing mutation allele that may have been generated quite recently. The fragrance allele has dispersed as a result of out-crossing under local environmental conditions.
Project description:ContextThe formation of red cell alloantibodies resulting from both transfusion and pregnancy can cause adverse effects from allogeneic blood transfusions. Alloanti-E is commonly detected among Thai and Asian populations.AimsThis study aimed to determine RHCE*E and RHCE*e genotype incompatibility in a southern Thai Muslim population and to compare it with those previously reported for other populations.Subjects and methodsNine hundred and twenty-seven DNA samples obtained from 427 unrelated healthy blood donors from southern Thai Muslims and 500 samples from Central Thais were included. Samples were genotyped for RHCE*E and RHCE*e using an in-house polymerase chain reaction with the sequence-specific primer technique.ResultsSignificant differences were found when we compared the allele frequencies of the RHCE*E and RHCE*e between southern Thai Muslims and Central Thais: RHCE*E 0.162 versus 0.197 and RHCE*e 0.838 versus 0.803 and also found in Chinese, American native, Japanese, Korean, Alaskan native, Hawaiian, South Asian, Brazilian Japanese-descendant, and Malay Malaysian populations (P < 0.05). In addition, the E/e incompatibilities among southern Thai Muslims and Central Thais were 24.23% and 26.71%, respectively.ConclusionsThis study was the first to determine the RHCE*E and RHCE*e genotype incompatibility among southern Thai Muslims, enabling the estimation of their potential alloimmunization risk. These data could be useful to provide safe blood transfusions across ethnic populations.
Project description:Two-locus two-allele models are among the most studied models in population genetics. The reason is that they are the simplest models to explore the role of epistasis for a variety of important evolutionary problems, including the maintenance of polymorphism and the evolution of genetic incompatibilities. Many specific types of models have been explored. However, due to the mathematical complexity arising from the fact that epistasis generates linkage disequilibrium, few general insights have emerged. Here, we study a simpler problem by assuming that linkage disequilibrium can be ignored. This is a valid approximation if selection is sufficiently weak relative to recombination. The goal of our paper is to characterize all possible equilibrium structures, or more precisely and general, all robust phase portraits or evolutionary flows arising from this weak-selection dynamics. For general fitness matrices, we have not fully accomplished this goal, because some cases remain undecided. However, for many specific classes of fitness schemes, including additive fitnesses, purely additive-by-additive epistasis, haploid selection, multilinear epistasis, marginal overdominance or underdominance, and the symmetric viability model, we obtain complete characterizations of the possible equilibrium structures and, in several cases, even of all possible phase portraits. A central point in our analysis is the inference of the number and stability of fully polymorphic equilibria from the boundary flow, i.e., from the dynamics at the four marginal single-locus subsystems. The key mathematical ingredient for this is index theory. The specific form of epistasis has both a big influence on the possible boundary flows as well as on the internal equilibrium structure admitted by a given boundary flow.