Diversity of variant alleles encoding Kidd, Duffy, and Kell antigens in individuals with sickle cell disease using whole genome sequencing data from the NHLBI TOPMed Program

BACKGROUND

Genetic variants in the SLC14A1, ACKR1, and KEL genes, which encode Kidd, Duffy, and Kell red blood cell antigens, respectively, may result in weakened expression of antigens or a null phenotype. These variants are of particular interest to individuals with sickle cell disease (SCD), who frequently undergo chronic transfusion therapy with antigen-matched units. The goal was to describe the diversity and the frequency of variants in SLC14A1, ACKR1, and KEL genes among individuals with SCD using whole genome sequencing (WGS) data.

STUDY DESIGN AND METHODS

Two large SCD cohorts were studied: the Recipient Epidemiology and Donor Evaluation Study III (REDS-III) (n = 2634) and the Outcome Modifying Gene in SCD (OMG) (n = 640). Most of the studied individuals were of mixed origin. WGS was performed as part of the National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine (TOPMed) program.

RESULTS

In SLC14A1, variants included four encoding a weak Jka phenotype and five null alleles (JKnull ). JKA*01N.09 was the most common JKnull . One possible JKnull mutation was novel: c.812G>T. In ACKR1, identified variants included two that predicted Fyx (FY*X) and one corresponding to the c.-67T>C GATA mutation. The c.-67T>C mutation was associated with FY*A (FY*01N.01) in four participants. FY*X was identified in 49 individuals. In KEL, identified variants included three null alleles (KEL*02N.17, KEL*02N.26, and KEL*02N.04) and one allele predicting Kmod phenotype, all in heterozygosity.

CONCLUSIONS

We described the diversity and distribution of SLC14A1, ACKR1, and KEL variants in two large SCD cohorts, comprising mostly individuals of mixed ancestry. This information may be useful for planning the transfusion support of patients with SCD.

Effect of Convalescent Plasma in Critically Ill Patients With COVID-19: An Observational Study

Background: Convalescent plasma is a potential therapeutic option for critically ill patients with coronavirus disease 19 (COVID-19), yet its efficacy remains to be determined. The aim was to investigate the effects of convalescent plasma (CP) in critically ill patients with COVID-19.

Methods: This was a single-center prospective observational study conducted in Rio de Janeiro, Brazil, from March 17th to May 30th, with final follow-up on June 30th. We included 113 laboratory-confirmed COVID-19 patients with respiratory failure. Primary outcomes were time to clinical improvement and survival within 28 days. Secondary outcomes included behavior of biomarkers and viral loads. Kaplan–Meier analyses and Cox proportional-hazards regression using propensity score with inverse-probability weighing were performed.

Results: 41 patients received CP and 72 received standard of care (SOC). Median age was 61 years (IQR 48–68), disease duration was 10 days (IQR 6–13), and 86% were mechanically ventilated. At least 29 out of 41CP-recipients had baseline IgG titers ≥ 1:1,080. Clinical improvement within 28 days occurred in 19 (46%) CP-treated patients, as compared to 23 (32%) in the SOC group [adjusted hazard ratio (aHR) 0.91 (0.49–1.69)]. There was no significant change in 28-day mortality (CP 49% vs. SOC 56%; aHR 0.90 [0.52–1.57]). Biomarker assessment revealed reduced inflammatory activity and increased lymphocyte count after CP.

Conclusions: In this study, CP was not associated with clinical improvement or increase in 28-day survival. However, our study may have been underpowered and included patients with high IgG titers and life-threatening disease.

Clinical Trial Registration: The study protocol was retrospectively registered at the Brazilian Registry of Clinical Trials (ReBEC) with the identification RBR-4vm3yy (http://www.ensaiosclinicos.gov.br).

REAÇÕES EM CASCATA ENZIMÁTICA, QUIMIOENZIMÁTICA E FOTOENZIMÁTICA: PERSPECTIVAS PARA UMA SÍNTESE ORGÂNICA MAIS SUSTENTÁVEL

ENZYMATIC, CHEMOENZYMATIC AND PHOTOENZYMATIC CASCADE REACTIONS: PERSPECTIVES FOR A MORE SUSTAINABLE ORGANIC SYNTHESIS. Chemicals are rarely the result of a single transformation but rather the consequence of several individual reaction steps. Classically, these individual steps are carried out in sequence, including isolation and purification of the intermediate products. However, the reasons for choosing to carry out cascade reactions can be multiple, such as (i) the chance to prepare unstable and/or toxic intermediates, which are consumed directly in a subsequent step, (ii) the option to shift the equilibrium of a reaction by removing the co (product), or (iii) simply bypass the tedious work of isolating and purifying intermediates, saving reagents, solvents, time and money, and still generating less waste. Therefore, it is not surprising that so-called cascade reactions are gaining considerable interest in academic and industrial research. The purpose of this review is to show recent, promising research and new trends, the potential and current limitations of cascade reactions in organic synthesis that involves at least one enzymatic step in the cascade. This review will address cascades involving multi enzymatic, chemoenzymatic, and photoenzymatic cascades, where all steps are performed in one reaction vessel simultaneously or sequentially and the cascades in the regime of continuous flow.

[Neonatal screening for hemoglobinopathies in Rio de Janeiro, Brazil]

OBJECTIVE

To describe the main results obtained in the first 15 months of neonatal screening for sickle cell disease in the state of Rio de Janeiro, Brazil, from August 2000 to November 2001.

METHODS

Starting in August 2000, blood samples began to be collected for sickle cell disease screening from all newborns receiving care in primary health care clinics in the state of Rio de Janeiro. The samples were submitted to high-resolution liquid chromatography. If the resulting chromatogram was compatible with sickle cell disease, the child and the parents were referred for diagnostic confirmation and treatment.

RESULTS

Between August 2000 and November 2001, 99 260 newborns were screened. There was one case of homozygous Hb C. On average, one of every 27 newborns who were screened presented sickle cell trait (Hb AS). Sickle cell disease was observed in 83 cases, or one new case in each 1 196 births. The 83 consisted of: 62 Hb S, 18 Hb SC, and 3 Hb SD. One child did not appear for diagnostic confirmation. The 82 children who were followed up by the program presented 15 intercurrent illnesses (upper respiratory infections, fever, splenic sequestration crises, hand-foot syndrome, and vascular occlusion), resulting in seven hospital admissions. Blood transfusions were necessary with 15 children, but none developed alloimmunization. All the other babies were doing well with the use of prophylactic penicillin.

CONCLUSIONS

Our data show the importance of early diagnosis for sickle cell disease, so as to prevent the frequent infectious complications faced by these patients.