beta Thalassemia associated with increased HB F production. Evidence for the existence of a heterocellular hereditary persistence of fetal hemoglobin (HPFH) determinant linked to beta thalassemia in a southern Italian population

The Novel Role of the B-Cell Lymphoma/Leukemia 11A (BCL11A) Gene in β-Thalassaemia Treatment

β-thalassaemia is a genetic disorder resulting in a reduction or absence of β-globin gene expression. Due to the high prevalence of β-thalassaemia and the lack of available treatment other than blood transfusion and haematopoietic stem cell (HSC) transplantation, the disease represents a considerable burden to clinical and economic systems. Foetal haemoglobin has an appreciated ameliorating effect in β-haemoglobinopathy, as the γ-globin chain substitutes the β-globin chain reduction by pairing with the excess α-globin chain in β-thalassaemia and reduces sickling in sickle cell disease (SCD). BCL11A is a critical regulator and repressor of foetal haemoglobin. Downregulation of BCL11A in adult erythroblasts and cell lines expressing adult haemoglobin led to a significant increase in foetal haemoglobin levels. Disruption of BCL11A erythroid enhancer resulted in disruption of the BCL11A gene solely in the erythroid lineages and increased γ-globin expression in adult erythroid cells. Autologous haematopoietic stem cell gene therapy represents an attractive treatment option to overcome the immune complications and donor availability associated with allogeneic transplantation. Using genome editing technologies, the disruption of BCL11A to induce γ- globin expression in HSCs has emerged as an alternative approach to treat β-thalassaemia. Targeting the +58 BCL11A erythroid enhancer or BCL11A binding motif at the γ-gene promoter with CRISPR-Cas9 or base editors has successfully disrupted the gene and the binding motif with a subsequent increment in HbF levels. This review outlines the critical role of BCL11A in γ-globin gene silencing and discusses the different genome editing approaches to downregulate BCL11A as a means for ameliorating β-thalassaemia.

It's Not Just What You Do but the Way You Do It: A Systematic Review of Process Evaluation of Interventions to Improve Gross Motor Competence

BACKGROUND

Motor competence is an important predictor of health behaviours. However, levels of motor competence are low in children and adolescents. Many interventions have improved motor competence, yet intervention effects were highly variable. Potential causes of such variations are not fully understood. Process evaluation can assist with the understanding of why an intervention worked or not, but its application and reporting in motor competence interventions has received little attention.

OBJECTIVES

The primary aim of this review was to investigate whether process evaluations have been reported in interventions to improve motor competence and, if reported, which process evaluation measures have been used. A secondary aim was to explore the association of intervention characteristics and process evaluation findings (outcomes of process evaluation measures) with intervention outcomes, in a search for what process evaluation measures may impact on intervention functioning and outcomes.

METHODS

The process of conducting and reporting this review adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review protocol was registered with PROSPERO (CRD42019124412). A systematic search of seven electronic databases (i.e. MEDLINE [via EBSCOhost], Cochrane Central Register of Controlled Trials [CENTRAL], CINAHL, Academic Search Complete, Education Database, SPORTDiscus and Scopus) was conducted with no date restrictions. Eligibility criteria included the following: (1) a study sample of typically developing children and adolescents aged 5-18 years, (2) an intervention aimed to improve motor competence, (3) an intervention included a control group, (4) a report of motor competence outcome at both pre- and post-intervention. Only original articles published in English in peer-reviewed journals were considered. Process evaluation measures and findings were extracted using the UK Medical Research Council's process evaluation framework in order to provide overarching descriptions on the implementation, mechanism of change and context of interventions. Univariable meta-regressions were performed to ascertain whether selected study-level covariates moderated the improvement in motor competence outcomes in interventions.

RESULTS

The search identified 60 intervention studies. Only 30 studies (50%) reported process evaluation measures. No studies reported (or employed) theoretical frameworks to guide process evaluation. Process evaluation measures relating to implementation were most commonly reported, with the most prevalent aspect being fidelity. This was followed by reporting on measures relating to mechanism of change and context of the intervention. Meta-analysis results suggested intervention duration, dose, inclusion of process evaluation aim, provision of lesson plans, sample size and sex as potential moderators.

CONCLUSIONS

Reporting of process evaluation measures may help build our understanding of the optimal characteristics of motor competence interventions. However, process evaluation is under-used and/or under-reported. This review serves as a call for more process evaluations and better reporting in motor competence interventions.

Prenatal diagnosis of a case with SEA-HPFH deletion thalassemia with whole HBB gene deletion

OBJECTIVE

The thalassemias is a group of hereditary disorders with impaired production of functional hemoglobin. In this report we described a rare case of compound heterozygous mutation of South-East Asia type hereditary persistence of fetal hemoglobin (SEA-HPFH) and β -thalassemia that allowed prenatal diagnosis to be performed in a subsequent pregnancy in the family.

CASE REPORT

The father showed a SEA-HPFH thalassemia trait phenotype, while his genotype revealed that he was heterozygous for the SEA-HPFH deletion; The mother genotype was heterozygote for IVS-II-654 mutation; the second child had co-inherited both parental mutations and was, thus, a compound heterozygote for β-thalassemia (IVS-II-654)/SEA-HPFH deletion. His phenotype was intermediate β-thalassemia. Prenatal genotyping of a fetal sample during the third pregnancy confirmed the fetus was only heterozygote for SEA-HPFH deletion and the parents elected to continue the pregnancy.

CONCLUSION

We described the clinical and molecular characterization of the first detected case of compound β-Thalassemia/SEA-HPFH deletion in Northern Vietnam. The report also highlighted the accuracy and necessity of mutation screening for families with thalassemia to inform accurate genetic counseling and targeted prenatal diagnosis when desired.

Clinical and haematological evaluation of beta thalassaemia intermedia with increased Hb F and Hb A2 in heterozygotes: beta thalassaemia intermedia I

Family studies were performed in 10 patients from seven different families with homozygous beta zero thalassaemia intermedia and in three patients with homozygous beta+ or compound heterozygous beta+ and beta zero thalassaemia intermedia. In nine of the 10 families at least one of the parents was found to have raised Hb A2 and Hb F. In the heterozygotes with increased Hb A2 and Hb F, the means of Hb F and MCV were significantly higher than those observed in regular Hb A2 thalassaemia heterozygotes. However, the severity of imbalance in in vitro haemoglobin synthesis was similar in these two groups. The imbalance in the alpha/non-alpha synthetic ratio was heterogeneous in the patients, being 2.1 and 4.0. Segregation of the raised Hb F from the Hb A2 beta thalassaemia determinant was found to be possible in only one of the 36 heterozygotes. This may exclude the possibility of the presence of an additional determinant responsible for the activation of the gamma chain. The G gamma/A gamma ratio of Hb F was that of the fetal type (G gamma was between 50 and 71% of the total gamma chain). The A gamma T variant of gamma chain was not detected in cis of the beta zero thalassaemia determinant characterised by increased Hb F and Hb A2. A retrospective study of 180 patients with beta thalassaemia and their parents indicated that the combined rise in Hb A2 and Hb F was more common in the heterozygous parents (11 out of 30 parents) of the patients with beta zero thalassaemia than it was in the parents of patients with beta+ thalassaemia (three out of 140 parents). The presence of increased Hb A2 and Hb F in the heterozygote may in some cases determine the relative mildness of the disease.

Association of heterocellular HPFH, beta(+)-thalassaemia, and delta beta(0)-thalassaemia: haematological and molecular aspects

An Italian family in which heterocellular hereditary persistence of fetal haemoglobin (HPFH) interacts with both beta(+)- and delta beta-thalassaemia is described. The index case was an 8 year old girl who was presumed to inherit both heterocellular HPFH and beta (+)-thalassaemia from her mother and delta beta-thalassaemia from her father. She was healthy and never needed blood transfusions. The possible contribution of heterocellular HPFH to the less severe expression of the compound delta beta/beta(+)-thalassaemia heterozygosity is discussed. By DNA analysis the specific delta beta-thalassaemia defect on the gamma delta beta globin gene region has been established. In addition, a previously unreported association of a polymorphic restriction site haplotype with a beta (+)-thalassaemia mutation has been observed.

Heterocellular hereditary persistence of fetal hemoglobin (HPFH). Molecular mechanisms of abnormal gamma-gene expression in association with beta thalassemia and linkage relationship with the beta-globin gene cluster

We report a study of four families of Italian origin in which heterocellular HPFH is inherited linked to beta thalassemia over two or three generations. The HPFH + beta thalassemia carriers showed thalassemic blood pictures and elevated HbF and F-cell number without increase in the HbF/F-cell content. Association of this gene complex with a second beta thalassemia trait gives rise to a mild clinical picture characterized by 9-12 g/dl of mainly HbF in peripheral blood and no transfusion requirement. In two families, independent segregation of the HPFH or beta-thal trait was observed, and in one case the study of the DNA polymorphisms within the gamma delta beta gene cluster indicated that the HPFH mutation lies outside that DNA region. In one family the coexistence of a polymorphic variant of the A gamma chain (the A gamma T chain) allowed us to demonstrate that the increased gamma chain synthesis caused by the heterocellular HPFH determinant is directed by both chromosomes.

Molecular heterogeneity of beta thalassaemia in the Italian population

Fifty-one subjects originating from Southern Italy and affected by Cooley's anaemia have been studied in order to define the degree of heterogeneity of beta thalassaemia mutations in this high incidence area. Restriction endonuclease mapping has been carried out on genomic DNA by the Southern blot technique both to exclude the existence of gross deletions or rearrangements and to establish the relative frequency of four polymorphic restriction sites (i.e. G gamma and A gamma Hind III, beta Ava II and beta Bam HI) within the gamma delta beta gene region. In 28 subjects unequivocal linkage of the four polymorphic sites has been determined leading to the identification of seven different chromosome haplotypes, six of which had previously been reported associated with specific beta(0) and beta(+) thalassaemia mutations. Globin chain synthesis studies on peripheral blood reticulocytes indicated that subjects carrying the same genotype may behave differently as far as the beta chain production is concerned relative to both the alpha and the non-alpha chains. Thus, beta thalassaemia turns out to be quite heterogeneous even in this limited geographical area. Beta(+) mutations appear to be predominant, particularly those affecting nuclear precursor RNA splicing to mature beta globin mRNA.

Unusual combination of genetic defects in a Sicilian boy: G gamma delta beta thalassemia, G gamma A gamma heterocellular HPFH, beta (0) thalassemia, and albinism

We describe the clinical and hematological findings in a 5-year-old boy with G gamma A gamma delta beta thalassemia, a G gamma A gamma heterocellular form of HPFH, beta(0) thalassemia, and albinism. Clinically he manifested only the characteristics of beta-thalassemia trait and not the typical picture of doubly heterozygous beta thal/delta beta thal. The simultaneous presence of heterocellular HPFH improves gamma chain synthesis, thus reducing the alpha chain excess. It is also possible that gene expression can be modified by the presence of other genetic anomalies.