Compound Heterozygosity of β-Thalassemia and the Sickle Cell Hemoglobin in Various Populations of Chhattisgarh State, India

Never-homozygous genetic variants in healthy populations are potential recessive disease candidates

The rapid pace with which genetic variants are now being determined means there is a pressing need to understand how they affect biological systems. Variants from healthy individuals have previously been used to study blood groups or HLA diversity and to identify genes that can apparently be nonfunctional in healthy people. These studies and others have observed a lower than expected frequency of homozygous individuals for potentially deleterious alleles, which would suggest that several of these alleles can lead to recessive disorders. Here we exploited this principle to hunt for potential disease variants in genomes from healthy people. We identified at least 108 exclusively heterozygous variants with evidence for an impact on biological function. We discuss several examples of candidate variants/genes including CCDC8, PANK3, RHD and NLRP12. Overall, the results suggest there are many, comparatively frequent, potentially lethal or disease-causing variants lurking in healthy human populations.

Common, But Neglected: A Comprehensive Review of Leg Ulcers in Sickle Cell Disease

OBJECTIVE

To compile available evidence to better understand the management of leg ulcers in sickle cell disease (SCD), as well as describe potential therapeutic steps that may be required to improve the quality of life of patients with SCD leg ulcers.

DATA SOURCES

MEDLINE, PubMed, EMBASE, and Web of Science databases.

STUDY SELECTION

A comprehensive search was conducted to retrieve relevant studies using the keywords "sickle cell disease and leg ulcer," "ulcer treatments, diagnosis and sickle cell," and "wound sickle cell." Studies published through July 2020 were included.

DATA EXTRACTION

Two independent authors selected all studies that assessed the relationship between leg ulcer and SCD identified from online databases.

DATA SYNTHESIS

The authors have summarized updated information on pathophysiology (vasculopathy linked to chronic hemolysis and endothelial dysfunction), diagnosis, and available treatment options to unravel the dermohematologic connection between leg ulcers and SCD.

CONCLUSIONS

It is the authors' hope that this detailed discussion of the information available on leg ulcers and SCD will lead to a better appreciation of this clinical problem by the clinicians and researchers and in turn have a long-term positive effect on the quality of life of patients with SCD. Researchers should design new trials considering these insights and potential therapeutic approaches based on current knowledge.

Erythrocyte microRNAs: a tiny magic bullet with great potential for sickle cell disease therapy

Sickle cell disease (SCD) is a severe hereditary blood disorder caused by a mutation of the beta-globin gene, which results in a substantial reduction in life expectancy. Many studies are focused on various novel therapeutic strategies that include re-activation of the γ-globin gene. Among them, expression therapy caused by the fetal hemoglobin (HbF) at a later age is highly successful. The induction of HbF is one of the dominant genetic modulators of the hematological and clinical characteristics of SCD. In fact, HbF compensates for the abnormal beta chain and has an ameliorant effect on clinical complications. Erythropoiesis is a multi-step process that involves the proliferation and differentiation of a small population of hematopoietic stem cells and is affected by several factors, including signaling pathways, transcription factors, and small non-coding RNAs (miRNAs). miRNAs play a regulatory role through complex networks that control several epigenetic mechanisms as well as the post-transcriptional regulation of multiple genes. In this review, we briefly describe the current understanding of interactions between miRNAs, their molecular targets, and their regulatory effects in HbF induction in SCD.

β-Thalassemia pathogenic variants in a cohort of children from the East African coast

BACKGROUND

β-Thalassemia is rare in sub-Saharan Africa. Previous studies have suggested that it is limited to specific parts of West Africa. Based on hemoglobin A2 (HbA2 ) concentrations measured by HPLC, we recently speculated that β-thalassemia might also be present on the East African coast of Kenya. Here, we follow this up using molecular methods.

METHODS

We used raised hemoglobin A2 (HbA2 ) values (> 4.0% of total Hb) to target all HbAA members of a cohort study in Kilifi, Kenya, for HBB sequencing for β-thalassemia (n = 99) together with a sample of HbAA subjects with lower HbA2 levels. Because HbA2 values are artifactually raised in subjects carrying sickle hemoglobin (HbS) we sequenced all participants with an HPLC pattern showing HbS without HbA (n = 116) and a sample with a pattern showing both HbA and HbS.

RESULTS

Overall, we identified 83 carriers of four separate β-thalassemia pathogenic variants: three β0 -thalassemia [CD22 (GAA→TAA), initiation codon (ATG→ACG), and IVS1-3' end del 25bp] and one β+ -thalassemia pathogenic variants (IVS-I-110 (G→A)). We estimated the minimum allele frequency of all variants combined within the study population at 0.3%.

CONCLUSIONS

β-Thalassemia is present in Kilifi, Kenya, an observation that has implications for the diagnosis and clinical care of children from the East Africa region.