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Our long-term goal is to foster genetically informed reproductive health knowledge and behaviors among young adults with sickle cell disease (SCD) or sickle cell trait (SCT) with a web-based, tailored, multimedia intervention called CHOICES. CHOICES is designed to help young adults with SCD or SCT preconception to gain knowledge of genetic inheritance, specify their reproductive health intentions (their parenting plan), and engage in reproductive health behaviors concordant with their parenting plan. In a previous study, we found high acceptability of both the e-Book (usual care control) and CHOICES interventions. We also found sustained (24 months), significant effects on knowledge but not on behavior, most likely because half of the recruited group was not at risk for their children inheriting SCD. Hence, we propose an adequately powered randomized controlled trial with the CHOICES intervention and an e-Book control to compare their effects on genetic inheritance knowledge and at-risk reproductive health behaviors (immediate posttest and at 6, 12, 18, and 24 months). We will conduct subgroup analyses to provide insight into the baseline knowledge and behavior as well as the intervention effects in different demographic or acceptability groups. Given the scalability and low cost of CHOICES, if proved to be effective, it can reach the affected population at low cost.

The hemoglobinopathies, disorders of hemoglobin structure and production, protect against death from malaria 1 . In sub-Saharan Africa, two such conditions occur at particularly high frequencies: presence of the structural variant hemoglobin S and α + -thalassemia, a condition characterized by reduced production of the normal α-globin component of hemoglobin. Individually, each is protective against severe Plasmodium falciparum malaria 2 , 3 , 4 , but little is known about their malaria-protective effects when inherited in combination. We investigated this question by studying a population on the coast of Kenya and found that the protection afforded by each condition inherited alone was lost when the two conditions were inherited together, to such a degree that the incidence of both uncomplicated and severe P. falciparum malaria was close to baseline in children heterozygous with respect to the mutation underlying the hemoglobin S variant and homozygous with respect to the mutation underlying α + -thalassemia. Negative epistasis could explain the failure of α + -thalassemia to reach fixation in any population in sub-Saharan Africa.

Interventions to assist reproductive health decision-making in populations affected by sickle cell disease (SCD) or trait (SCT) lack proven efficacy over time. Our aim was to compare effects of CHOICES, a Web-based multimedia education program on implementing informed reproductive plans, and usual care education (e-Book) on reproductive knowledge, intention, and behavior over 24 months. We randomized 234 participants with SCD ( n  = 138) or SCT ( n  = 96) (age 18–35 years, 35 % male, 94 % African American) to CHOICES and e-Book groups. Participants completed a sickle cell-specific reproductive measure before and four times after the intervention (6, 12, 18 and 24 months). Compared to the e-Book group the CHOICES group had significantly more improvement in knowledge over time ( p  = .004) but not intention ( p  = .18) or behavior ( p  = .69). At baseline, 114 (48.7 %) participants reported having partners who would not put the couple at risk for their children inheriting SCD. Of the 116 (49.6 %) at - risk participants, a higher poroportion of those who were in the CHOICES group chose partners that reduced their risk by the last visit than the e-Book group ( p  = .04). Study findings provide important insights for designing a national trial of the CHOICES intervention focusing on subjects whose partner status puts them at risk for having a child with SCD.

The present study compared the changes in blood viscosity, hydration status, body temperature and heart rate between a group of sickle cell trait (SCT) carriers and a control (Cont) group before and after a soccer game performed in two conditions: one with water offered ad libitum (hydration condition; Hyd) and the other one without water (dehydration condition; Dehyd). Blood viscosity and haematocrit per blood viscosity ratio (HVR; an index of red blood cell oxygen transport effectiveness) were measured before and at the end of each game. Resting blood viscosity was greater in the SCT carriers than in the Cont group. The increase of blood viscosity over baseline at the end of the game in the Cont group was similar in the two conditions. In contrast, the change in blood viscosity occurring in SCT carriers during soccer games was dependant on the experimental condition: (1) in Dehyd condition, blood viscosity rose over baseline; (2) in Hyd condition, blood viscosity decreased below resting level reaching Cont values. The Cont group had higher HVR than SCT carriers at rest. HVR remained unchanged in the Cont group at the end of the games, whatever the experimental condition. Although HVR of SCT carriers decreased below baseline at the end of the game performed in Dehyd condition, it increased over resting level in Hyd condition reaching the values of the Cont group. Our study demonstrated that ad libitum hydration in exercising SCT carriers normalises the blood hyperviscosity.

The prevention and treatment of acute chest syndrome (ACS) is a major clinical concern in sickle cell disease (SCD). However, the mechanism underlying the pathogenesis of ACS remains elusive. We tested the hypothesis that the hemolysis byproduct hemin elicits events that induce ACS. Infusion of a low dose of hemin caused acute intravascular hemolysis and autoamplification of extracellular hemin in transgenic sickle mice, but not in sickle-trait littermates. The sickle mice developed multiple symptoms typical of ACS and succumbed rapidly. Pharmacologic inhibition of TLR4 and hemopexin replacement therapy prior to hemin infusion protected sickle mice from developing ACS. Replication of the ACS-like phenotype in nonsickle mice revealed that the mechanism of lung injury due to extracellular hemin is independent of SCD. Using genetic and bone marrow chimeric tools, we confirmed that TLR4 expressed in nonhematopoietic vascular tissues mediated this lethal type of acute lung injury. Respiratory failure was averted after the onset of ACS-like symptoms in sickle mice by treating them with recombinant hemopexin. Our results reveal a mechanism that helps to explain the pathogenesis of ACS, and we provide proof of principle for therapeutic strategies to prevent and treat this condition in mice.

Sickle cell disease (SCD) is one of the most frequent and traumatizing genetic disease in Uganda, with the prevalence of the sickle cell trait (SCT) estimated at 13.3% leading to serious psycho-social and economic impact on the patients and their families. This study aimed to determine the burden of SCT and factors influencing the uptake of screening services among secondary school students in Uganda. We used an analytical cross-sectional design with a multi-stage sampling approach. A total of 399 students from four secondary schools in Kampala City were enrolled in this study. Data were gathered using semi-structured questionnaires and blood screening. We used the sickling test to determine the presence of sickle cell alleles among the participants and hemoglobin electrophoresis as a confirmatory test. Data gathered using the questionnaire were analyzed using descriptive and inferential statistics. In total, 5.8% of participants who were tested during this study had SCT. Most (80.2%) participants were not in an intimate relationship at the time of data collection. The majority (60.4%) had moderate knowledge about SCT screening and obtained information about screening from the school. Only 29 (7.3%) participants knew of a family member with sickle cell. Overall, participants had a negative attitude toward SCT screening (67%), although 41.6% believed that most people who were sickle cell carriers did not live long and were often sick. Statistically significant associations were found between testing for SCT and knowing a partner's sickle cell status (odds ratio [OR] 2.112, p = 0.043) and Anglican religion (OR 2.075, p = 0.047). Despite the moderate level of knowledge and negative attitudes, a relatively large number of participants had SCT. This highlights the need for a comprehensive health education package targeting adolescents to promote SCD/SCT screening.

To determine the regional- and district-level newborn prevalence of sickle cell trait and disease, and the prevalence of haemoglobin variants and genetic modifiers of sickle cell disease, in the nine regions of north-western United Republic of Tanzania. We repurposed dried blood spot samples from children (aged 0-24 months) born to mothers living with human immunodeficiency virus (HIV), collected as part of the HIV Early Infant Diagnosis programme, for sickle cell diagnosis. We performed isoelectric focusing to determine whether samples had normal haemoglobin, sickle cell trait, sickle cell disease or a rare haemoglobin variant. We shipped samples diagnosed as disease or variant to Cincinnati Children's Hospital in the United States of America for deoxyribonucleic-acid-based analyses to determine the prevalence of α-thalassaemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency or fetal haemoglobin genetic modifiers. We analysed a total of 17 200 specimens during February 2017-May 2018. We observed a prevalence of sickle cell trait and disease of 20.3% (3492/17 200) and 1.2% (210/17 200), respectively. District-level trait varied from 8.6% (5/58) to 28.1% (77/274). Among confirmed sickle cell disease specimens, we noted 42.7% (61/143) had 1-gene deletion and 14.7% (21/143) had 2-gene deletion α-thalassaemia trait. We documented G6PD A deficiency in 19.2% (14/73) of males. Our calculated prevalence is twice as high as previously reported and reinforces the need for enhanced sickle cell diagnostic services. Our district-level data will inform public health policy, allowing screening and disease-modifying hydroxyurea therapy to be focused on high-prevalence areas, until universal newborn screening is available.

The key problem in human infectious diseases was posed at the turn of the 20th century: their pathogenesis. For almost any given virus, bacterium, fungus, or parasite, life-threatening clinical disease develops in only a small minority of infected individuals. Solving this infection enigma is important clinically, for diagnosis, prognosis, prevention, and treatment. Some microbes will inevitably remain refractory to, or escape vaccination, or chemotherapy, or both. The solution also is important biologically, because the emergence and evolution of eukaryotes alongside more rapidly evolving prokaryotes, archaea, and viruses posed immunological challenges of an ecological and evolutionary nature. We need to study these challenges in natural, as opposed to experimental, conditions, and also at the molecular and cellular levels. According to the human genetic theory of infectious diseases, inborn variants underlie life-threatening infectious diseases. Here I review the history of the field of human genetics of infectious diseases from the turn of the 19th century to the second half of the 20th century. This paper thus sets the scene, providing the background information required to understand and appreciate the more recently described monogenic forms of resistance or predisposition to specific infections discussed in a second paper in this issue.

Sickle cell disease (SCD) is caused by the homozygous beta-globin gene mutation that can lead to ischemic multi-organ damage and consequently reduce life expectancy. On the other hand, sickle cell trait (SCT), the heterozygous beta-globin gene mutation, is still considered a benign condition. Although the mechanisms are not well understood, clinical evidence has recently shown that specific pathological symptoms can also be recognized in SCT carriers. So far, there are still scant data regarding the morphological modifications referable to possible multi-organ damage in the SCT condition. Therefore, after genotypic and hematological characterization, by conventional light microscopy and transmission electron microscopy (TEM), we investigated the presence of tissue alterations in 13 heterozygous Townes mice, one of the best-known animal models that, up to now, was used only for the study of the homozygous condition. We found that endothelial alterations, as among which the thickening of vessel basal lamina, are ubiquitous in the lung, liver, kidney, and spleen of SCT carrier mice. The lung shows the most significant alterations, with a distortion of the general tissue architecture, while the heart is the least affected. Collectively, our findings contribute novel data to the histopathological modifications at microscopic and ultrastructural levels, underlying the heterozygous beta-globin gene mutation, and indicate the translational suitability of the Townes model to characterize the features of multiple organ involvement in the SCT carriers.

Objective To provide an up-to-date data, we aim to estimate the frequency of sickle cell disease among children in the pediatric clinics of the Sylvanus Olympio University Hospital, Lome, Togo, in 2022. Results A total of 317 children with a median age of 8 years (Interquartile range: 4–12) were included. Both parents knew their Hb phenotype in 7.3% of cases. Nineteen children had sickle cell disease (6.0%) and about 15.6% of the children had sickle cell trait AS. This study found a high frequency of children with sickle cell disease seen in pediatric clinics. We therefore emphasize the need for continued education to improve knowledge of the hemoglobin phenotype at community level and the importance of premarital screening to reduce this burden in the country.