Genomics and global health: time for a reappraisal

Molecular characterization of a novel homozygous deletion in β-globin cluster causing (δβ)0-Thalassemia among Tunisian family

BACKGROUND

Deletions in the β-globin cluster are uncommon and cause thalassemia (thal) with hereditary persistence of fetal hemoglobin. They constitute a heterogenous group of disorders characterized by absent or reduced synthesis of adult hemoglobin (Hb A) and increased synthesis of fetal hemoglobin (Hb F). Although the clinical severity of these disorders are asymptomatic owing to the increased Hb F levels, the molecular basis is very heterogenous due to the large deletions in the β-globin cluster spanning both HBD and HBB genes. Here, we describe a Tunisian family carrying a novel deletion mutation causing (δβ)°-thalassemia.

METHODS

The amounts of hemoglobin fractions were measured by capillary electrophoresis of hemoglobin. Amplification and sequencing of different regions on the β-gene cluster were performed by Sanger method.

RESULTS

Family study and genetic analysis revealed a large deletion mutation in the β-globin cluster of 14.5 kb (NG_000,007.3:g. 58,253 to g.72837del14584) at the homozygous state in the patient and at heterozygous state at the other members of the family. This deletion removes the HBD and HBB genes.

CONCLUSIONS

In our knowledge, this new large deletion is described for the first time in the Tunisian population and in the world, designed Tunisian(δβ)⁰ in Ithanet database (IthaID: 3971). Therefore, it is important to identify the deletion leading to δβ-thalassemia carriers at the molecular level, to highlight the importance of recognizing the clinical features and implementing appropriate testing to clarify the diagnosis and manage the condition.

Genetic research and clinical analysis of deletional Chinese Gγ+(Aγδβ)0 -thalassemia and Southeast Asian HPFH in South China

Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia and SEA-HPFH are the most common types of β-globin gene cluster deletion in Chinese population. The aim of the study was to analyze clinical features of deletional Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia and Southeast Asian hereditary persistence of fetal hemoglobin (SEA-HPFH) in South China. A total of 930 subjects with fetal hemoglobin (HbF) level ≥ 2% were selected on genetic research of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia and SEA-HPFH. The gap polymerase chain reaction was performed to identify the deletions. One hundred cases of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia were detected, including 90 cases of Chinese ^Gγ⁺(^Aγδβ)⁰/β^N-thalassemia, 7 cases of Chinese ^Gγ⁺(^Aγδβ)⁰ /β^N-thalassemia combined with α-thalassemia, 2 cases of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia combined with β-thalassemia, and 1 case of Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia combined with β-gene mutation. One hundred nine cases of SEA-HPFH were detected, including 97 cases of SEA-HPFH/β^N, 9 cases of SEA-HPFH/β^N combined with α-thalassemia, 2 cases of SEA-HPFH combined with β-thalassemia, and 1 case of SEA-HPFH combined with β-gene mutation. Statistical analysis indicates significant differences in MCV (mean corpuscular volume), MCH (mean corpuscular hemoglobin), and HbA2 and HbF levels between Chinese ^Gγ⁺(^Aγδβ)⁰-thalassemia heterozygotes and SEA-HPFH heterozygotes (P < 0.001). There are statistical differences in hematological parameters between them. Clinical phenotypic analysis can provide guidance for genetic counseling and prenatal diagnosis.

[Targeted newborn screening for sickle-cell anemia: Sickling test (Emmel test) boundaries in the prenatal assessment in West African area]

BACKGROUND

Newborn screening for sickle cell anemia is necessary in Africa where the disease is more frequent. Hemoglobin electrophoresis is used for screening, but is limited by a high cost and difficult access. Sickling test (Emmel test), which is more affordable and technically more accessible, is often requested for prenatal assessment of pregnant women in West African areas to reserve screening for newborns from mothers in whom the positive sickling test attests the presence of hemoglobin S. This study aims to evaluate the number of undetected sickle cell anemia newborns by a screening policy targeting only newborns from mothers in whom a sickling test would have been positive.

METHODS

From 2010 to 2012, in Bamako, Mali, West Africa, 2489 newborns were routinely screened for sickle cell anemia at the umbilical cord or heel by isoelectrofocusing and, if necessary, by high-performance liquid chromatography. These newborns were born from 2420 mothers whose hemoglobin was studied by isoelectrofocusing. The data was recorded and processed using Excel software version 14.0.0. We calculated the frequency of the sickle cell gene in mothers and newborns as well as the number of SCA newborns from heterozygous or C homozygous mothers.

RESULTS

Of the 2489 newborns, 16 had sickle cell anemia (6 SS and 10 SC); 198 had the sickle cell trait; 139 were AC and 1 was CC. Of the 10 newborns with SC profile, 3 were born from mothers not carrying the S gene but the C gene of hemoglobin and in which an Emmel test would have been negative.

CONCLUSION

Targeted newborn screening, based on the results of sickling test in pregnant women, would misdiagnose more than one of six sickle cell anemia newborns who would not benefit from early care. Cost-effectiveness studies of routine newborn screening for sickle cell anemia should lead to a better screening strategy in contexts where hemoglobin S and other hemoglobin defect genes coexist.

The prevalence and molecular spectrum of α- and β-globin gene mutations in 14,332 families of Guangdong Province, China

OBJECTIVE

To reveal the familial prevalence and molecular variation of α- and β-globin gene mutations in Guangdong Province.

METHODS

A total of 40,808 blood samples from 14,332 families were obtained and analyzed for both hematological and molecular parameters.

RESULTS

A high prevalence of α- and β-globin gene mutations was found. Overall, 17.70% of pregnant women, 15.94% of their husbands, 16.03% of neonates, and 16.83% of couples (pregnant women and their husbands) were heterozygous carriers of α- or β-thalassemia. The regions with the highest prevalence were the mountainous and western regions, followed by the Pearl River Delta; the region with the lowest prevalence was Chaoshan. The total familial carrier rate (both spouses were α- or β-thalassemia carriers) was 1.87%, and the individual carrier rates of α- and β-thalassemia were 1.68% and 0.20%, respectively. The total rate of moderate-to-severe fetal thalassemia was 12.78% among couples in which both parents were carriers.

CONCLUSIONS

There was a high prevalence of α- and β-thalassemia in Guangdong Province. This study will contribute to the development of thalassemia prevention and control strategies in Guangdong Province.

Sickle cell disease: new opportunities and challenges in Africa

Sickle cell disease (SCD) is one of the most common genetic causes of illness and death in the world. This is a review of SCD in Africa, which bears the highest burden of disease. The first section provides an introduction to the molecular basis of SCD and the pathophysiological mechanism of selected clinical events. The second section discusses the epidemiology of the disease (prevalence, morbidity, and mortality), at global level and within Africa. The third section discusses the laboratory diagnosis and management of SCD, emphasizing strategies that been have proven to be effective in areas with limited resources. Throughout the review, specific activities that require evidence to guide healthcare in Africa, as well as strategic areas for further research, will be highlighted.

Neurocognitive function in patients with β-thalassemia major

BACKGROUND

Children with β-thalassemia major (β-TM) have multiple risk factors for developing cognitive impairment. The aim of the present study was to evaluate cognitive function in patients with β-TM.

METHODS

Twenty children with β-TM were enrolled into the study and were compared with a control group consisting of 21 healthy children. All participants were evaluated with neuropsychological tests and event-related potentials (ERP).

RESULTS

All of the participants had normal IQ scores, but the patient group had significantly lower full-scale, performance, and verbal IQs compared with the control group (P < 0.05). The number of children with visuomotor dysfunction was higher in the patient group compared with the control group (P < 0.05). In the P300 test, the patient group had significantly prolonged N1, P2 and N2 latencies at the FZ, and a prolonged N1 latency at the Cz compared with the control group (P < 0.05). The patient group also had lower N1 and P3N4 amplitudes at the Fz, and lower N1, N1P2 and P3N4 amplitudes at the Cz when compared with the control group (P < 0.05). Mismatch negativity latency and duration were longer in the patient group (P < 0.05).

CONCLUSIONS

Neuropsychological tests are safe, and reliable for the diagnosis of cognitive impairment in β-TM patients, and the use of ERP may facilitate early diagnosis. The number of β-TM patients in the present study was limited, however, and larger numbers of patients are required in further studies.

'All her children are born that way': gendered experiences of stigma in families affected by sickle cell disorder in rural Kenya

OBJECTIVES

To explore early experiences of sickle cell disorder (SCD) in families with a young affected child, and the way these experiences influence relations within families. To consider ways in which stigma could be counteracted in health and research programmes in sub Saharan Africa.

DESIGN

A qualitative study was conducted in a rural area of coastal Kenya including in-depth interviews with 13 families affected by SCD and 12 staff of a local biomedical research progamme. Purposive selection aimed to maximize diversity in socioeconomic and educational status, religion, severity of illness burden and religion amongst families and draw on relevant experience for staffs. Interviews were recorded, transcribed and analysed using the constant comparative method for family interviews and a thematic framework approach for staff data.

RESULTS

Low initial recognition of SCD and its cause were associated with lay practices of surveillance within affected families, contributing to stigmatisation that occurred independently of genetic knowledge. Blame was often placed on mothers, including a risk of blame for misaligned paternity. Mothers are often particularly affected by SCD through the loss of independent livelihoods and their limited options in coping with this chronic condition.

CONCLUSIONS

Mothers of children with SCD were particularly vulnerable to stigmatisation within families, with underlying structural influences that suggest these findings may apply to other similar settings in Africa, and have relevance for other genetic conditions. The potential, nature and form of stigmatisation point to the role of effective communication and SCD management in addressing for blame and discriminative effects of having a child with SCD. The findings highlight the importance of broader social programmes targeting underlying gender and economic inequalities.

Experiences with community engagement and informed consent in a genetic cohort study of severe childhood diseases in Kenya

BACKGROUND

The potential contribution of community engagement to addressing ethical challenges for international biomedical research is well described, but there is relatively little documented experience of community engagement to inform its development in practice. This paper draws on experiences around community engagement and informed consent during a genetic cohort study in Kenya to contribute to understanding the strengths and challenges of community engagement in supporting ethical research practice, focusing on issues of communication, the role of field workers in 'doing ethics' on the ground and the challenges of community consultation.

METHODS

The findings are based on action research methods, including analysis of community engagement documentation and the observations of the authors closely involved in their development and implementation. Qualitative and quantitative content analysis has been used for documentation of staff meetings and trainings, a meeting with 24 community leaders, and 40 large public and 70 small community group meetings. Meeting minutes from a purposive sample of six community representative groups have been analysed using a thematic framework approach.

RESULTS

Field workers described challenges around misunderstandings about research, perceived pressure for recruitment and challenges in explaining the study. During consultation, leaders expressed support for the study and screening for sickle cell disease. In community meetings, there was a common interpretation of research as medical care. Concerns centred on unfamiliar procedures. After explanations of study procedures to leaders and community members, few questions were asked about export of samples or the archiving of samples for future research.

CONCLUSIONS

Community engagement enabled researchers to take account of staff and community opinions and issues during the study and adapt messages and methods to address emerging ethical challenges. Field workers conducting informed consent faced complex issues and their understanding, attitudes and communication skills were key influences on ethical practice. Community consultation was a challenging concept to put into practice, illustrating the complexity of assessing information needs and levels of deliberation that are appropriate to a given study.

How I use hydroxyurea to treat young patients with sickle cell anemia

Hydroxyurea has many characteristics of an ideal drug for sickle cell anemia (SCA) and provides therapeutic benefit through multiple mechanisms of action. Over the past 25 years, substantial experience has accumulated regarding its safety and efficacy for patients with SCA. Early proof-of-principle studies were followed by prospective phase 1/2 trials demonstrating efficacy in affected adults, then adolescents and children, and more recently infants and toddlers. The phase 3 National Heart, Lung and Blood Institute-sponsored Multicenter Study of Hydroxyurea trial proved clinical efficacy for preventing acute vaso-occlusive events in severely affected adults. Based on this cumulative experience, hydroxyurea has emerged as an important therapeutic option for children and adolescents with recurrent vaso-occlusive events; recent evidence documents sustained long-term benefits with prevention or reversal of chronic organ damage. Despite abundant evidence for its efficacy, however, hydroxyurea has not yet translated into effective therapy for SCA. Because many healthcare providers have inadequate knowledge about hydroxyurea, patients and families are not offered treatment or decline because of unrealistic fears. Limited support for hydroxyurea by lay organizations and inconsistent medical delivery systems also contribute to underuse. Although questions remain regarding its long-term risks and benefits, current evidence suggests that many young patients with SCA should receive hydroxyurea treatment.

The global problem of genetic disease

Inherited haemoglobin disorders will undoubtedly cause an increasing health burden in many developing countries. Although much is known about their molecular pathology and the mechanisms for their phenotypic diversity, many important questions remain, not least the role of the environment in modifying the clinical course. Methods for screening these conditions are now well established and inexpensive and it is vital that they are applied to define the magnitude of the problem that will be posed by these conditions in the future. Similarly, they form the basis for widespread screening and counselling programmes directed at developing prenatal diagnosis expertise where this is not available. Answers to some relatively simple questions about the role of the environment could also make a major difference to the management of the haemoglobin disorders. There is a major case for the development of regional networks to apply such technology as has been developed for the control and prevention of the important haemoglobin disorders, particularly in Asian countries.

Current status of thalassemia in minority populations in Guangxi, China

Thalassemia is one of the most common monogenic disorders in the world. In order to develop a community-based prevention program, we screened 12,900 individuals for alpha- and beta-thalassemia in Baise City, Guangxi, China, with hematological methods and molecular assays. We found that the frequency of carriers in this area for alpha-thalassemia is 15%. Beta-thalassemia carriers comprise 4.8% of the populations. Five mutations account for 98% of alpha-thalassemia [--SEA 46.7%; -alpha/4.2, 23.9%; -alpha/3.7, 21.7%; hemoglobin (Hb) Constant Spring, 6.5%; Hb Quong Sze, 1.1%]. Seven mutations in the beta-globin gene account for 99% of the mutations [codon (CD) 41/42 (-TCTT) (39.4%), CD 17(A-->T) (32%), CD 71/72 (+A) (7.4%), -28 (A-->G) (5.8%), IVS-2-654 (C-->T) (5.8%), CD26 (Hb E) (4%), IVS-1 (G-->A) (3.7%), and CD 43(G-->T) (1.9%)]. Most individuals with alpha-thalassemia major die in the uterus or shortly after birth. Among 106 patients with beta-thalassemia major followed by our clinic, the majority died before 5 years of age. Knowledge surveys about thalassemia were conducted. Our results show a severe lack of knowledge about thalassemia in both medical professionals and in the general populations. This study shows that thalassemia is a very severe public health issue in minority populations in Baise City, China. Identification of the common mutations will allow us to design cost-effective molecular tests. There is an urgent need to educate the general population and the medical community for a successful community-based prevention program.

Valid consent for genomic epidemiology in developing countries

Drawing on experience gained from ongoing research in Mali, this paper describes practical ethical challenges relating to the achievement of valid consent in genomic epidemiology.

Bias-corrected diagnostic performance of the naked-eye single-tube red-cell osmotic fragility test (NESTROFT): an effective screening tool for beta-thalassemia

It is being increasingly recognized that a majority of the countries in the thalassemia-belt need a cost-effective screening program as the first step towards control of thalassemia. Although the naked eye single tube red cell osmotic fragility test (NESTROFT) has been considered to be a very effective screening tool for beta-thalassemia trait, assessment of its diagnostic performance has been affected with the reference test- and verification-bias. Here, we set out to provide estimates of sensitivity and specificity of NESTROFT corrected for these potential biases. We conducted a cross-sectional diagnostic test evaluation study using data from 1563 subjects from Central India with a high prevalence of beta-thalassemia. We used latent class modelling after ensuring its validity to account for the reference test bias and global sensitivity analysis to control the verification bias. We also compared the results of latent class modelling with those of five discriminant indexes. We observed that across a range of cut-offs for the mean corpuscular volume (MCV) and the hemoglobin A2 (HbA2) concentration the average sensitivity and specificity of NESTROFT obtained from latent class modelling was 99.8 and 83.7%, respectively. These estimates were comparable to those characterizing the diagnostic performance of HbA2, which is considered by many as the reference test to detect beta-thalassemia. After correction for the verification bias these estimates were 93.4 and 97.2%, respectively. Combined with the inexpensive and quick disposition of NESTROFT, these results strongly support its candidature as a screening tool-especially in the resource-poor and high-prevalence settings.

Genomics and world health: hopes and realities

Due to lack of appreciation of the complexities of the interactions between nature and nurture, claims for the rapid improvements in medical care following the human genome project have been exaggerated. Although some progress has been made in certain fields, the full scope of genomic medicine may not be realised for many years.

A case for developing North-South partnerships for research in sickle cell disease

For a better understanding of the pathophysiology and mechanisms of phenotypic diversity of sickle cell disease, and for the improvement of its management globally, there is a strong case for developing sustainable research partnerships between rich and poor countries.

Texas physicians' perceptions of genomic medicine as an innovation

Primary care providers (PCPs) are believed to be the professionals who, in the near future, will be responsible for incorporating genomic medicine (GM) into primary care. Given the dearth of empirical data describing PCPs' beliefs about GM and the relationship between beliefs and the incorporation of GM into practice, this study assessed whether (and to what extent) PCPs' perceptions of GM as an innovation influence their likelihood of adopting this innovation into primary care. The study utilized diffusion of innovations theory as a framework. A state-wide representative sample of PCPs practicing in Texas responded to a mailed survey. The survey measured PCPs' perceptions of five characteristics of GM as an innovation. Findings suggest that among the five characteristics examined GM's relative advantage, compatibility with current practice, its complexity, and observability were the strongest predictors of likelihood to adopt GM tasks into primary care practice.