Phenotype and Genotype Frequency of β-Thalassemia and Sickle Cell Disease Carriers in Halkidiki, Northern Greece

Genetic variation patterns of β-thalassemia in Western Andalusia (Spain) reveal a structure of specific mutations within the Iberian Peninsula

BACKGROUND

Analyses of the genomic variation in the western Mediterranean population are being used to reveal its evolutionary history and to understand the molecular basis of particular diseases.

AIM

To observe the β-thalassemia mutational spectrum in western Andalusia, Spain, in the context of the Mediterranean. In addition, associations between disease and neutral gene variants within the β-globin gene (HBB) were also evaluated.

SUBJECTS AND METHODS

This study included 63 unrelated individuals diagnosed with β-thalassemia. In addition, 97 unrelated, healthy subjects of the same territory were also analysed as proxies of the normal genetic background. Allele associations and population genetic structure analyses were performed using different methodologies.

RESULTS

Data have revealed a rather restricted spectrum of β-thalassemia mutations in the analysed sample. Although the detected variants fit well with the Mediterranean pattern, certain singularities support a structure of some specific β-thalassemia alleles. The IVSI-1 (G > A) shows a strong regionalisation. The spatial correlogram revealed a typically narrow wave structure, presumably linked to genetic isolation and genetic drift.

CONCLUSIONS

The long history of endemic malaria in the study territory, the rather high consanguinity rates among its autochthonous population, and other demographic features have been used here to understand the western Andalusian β-thalassemia molecular portrait.

Total Annual Economic Burden of Patients with Sickle Cell Disease in Steady State in Greece

Sickle cell disease includes a group of congenital hemolytic anemias, all characterized by the predominance of Hb S (HBB: c.20A>T). The population movement due to economic migration or escape from conflict zones will further affect the health systems of countries by either increasing the number of patients or forcing countries to create care units for sickle cell disease patients. This will probably also increase the incidence of the disease in areas where their incidence and prevalence were previously low. In the present study, an attempt has been made to estimate the total annual cost of the treatment of sickle cell disease in Greece. This was the first attempt to calculate the total annual cost of treating sickle cell disease patients in a steady state. The annual cost of sickle cell disease was estimated to be €21,152,340.00 (US$25,219,300.41), without calculating the cost of hospitalization for severe complications. Since 2013, in Greece, a pharmaceutical expenditure limit (decreasing with the years) has been budgeted at €1,945,000,000.00 (US$2,318,965,150.00), annually. It is therefore calculated that approximately 1.0% of the budget allocated to pharmaceutical spending is used to treat patients with sickle cell disease.

Sexual dysfunction in female subjects with beta-thalassemia minor

Beta thalassemia minor (BTM) is a hereditary disease caused by defective globin synthesis and it is frequently asymptomatic or only mildly anemic. Female sexual dysfunction affects 21-41% of women worldwide. In this study we aimed to investigate female sexual dysfunction in subjects with BTM. A total of 183 subjects who had regular sexual intercourse with marital partners were enrolled in this cross-sectional study. The study group was comprised of 87 subjects with BTM and the control group included 96 healthy subjects. Hemoglobin electrophoresis were performed in all subjects, and all participants were assessed by the Female Sexual Function Index (FSFI) questionnaire and the Arizona Sexual Experience Scale (ASEX). The FSFI scores of the study group were significantly lower than in the control group (19.1 ± 9.6 vs. 25.2 ± 6.6, p < 0.001). Conversely, the ASEX scores of the study group were higher than in the control group (15.2 ± 41 vs. 13.5 ± 6.1, p = 0.0085). Sexual functions were poor in subjects with BTM in this study and we conclude that certain metabolic diseases associated with BTM, such as insulin resistance, hyperglycemia and dyslipidemia, may be the main causes of sexual dysfunctions in these subjects.

Use of an automated pyrosequencing technique for confirmation of sickle cell disease

BACKGROUND

The diagnosis of sickle cell disease (SCD) is made by hemoglobin assays such as high-performance liquid chromatography (HPLC), isoelectric focusing and cellulose acetate or citrate agar electrophoresis. These assays are easy to perform and used in large-scale newborn screening in many countries. These tests however may not easily differentiate Sβ0 thalassemia from SS or identify other hemoglobin variants, and in this case, hemoglobin (HBB) gene sequencing may be necessary.

OBJECTIVES

To develop a high throughput DNA based confirmatory assay for SCD and to detect mutations in the HBB gene.

METHODS

We developed an automated pyrosequencing technique (PyS) based on QIAGEN technology (Hilden, Germany) to detect homozygous or heterozygous hemoglobin S mutations as well as hemoglobin C mutations. The technique was tested on 2,748 samples from patients enrolled in a multi-center SCD cohort in Brazil. Patients were previously tested using HPLC to diagnose SCD as part of routine clinical care. Any subjects with discrepant results between HPLC and PyS or with heterozygous hemoglobin S detected had Sanger sequencing of the HBB gene.

RESULTS

We identified 168 samples with discrepant results between HPLC and PyS and 100 with concordant PyS = heterozygous S and HPLC, which would suggest SB-thalassemia or other heterozygous S variants. The PyS assay correctly identified 1906 (98.7%) of the 1930 HbSS and 628 (98.7%) of the 636 HbSC samples. Of the 179 remaining samples, PyS correctly indicated S heterozygosis in 165 (92.2%). Of the 165 heterozygous S samples confirmed by Sanger as consistent with Sβ thalassemia genotype, 84 samples were classified as Sβ0 thalassemia and 81 as Sβ+ thalassemia. The most frequent beta thalassemia mutations of Sβ0 and Sβ+ were HBB: c.118C>T (Gln40Stop) and HBB c.92 + 6T> C, respectively.

DISCUSSION

The PyS proved to be satisfactory for large-scale confirmatory testing of hemoglobin mutation. Moreover, with this study we were able to describe the most common β+ and β0 mutations in SCD patients with Sβ-thalassemia in a large multi-institutional SCD cohort in Brazil.

Favorable Pulse Wave Augmentation Indices and Left Ventricular Diastolic Profile in β-Thalassemia Minor

β-Thalassemia minor (β-Τm) is associated with rheological and biochemical alterations that can affect cardiovascular function. We aimed to evaluate the elastic arterial properties and the pulse wave augmentation indices in a population of patients with β-Τm. Seventy-five individuals with β-Τm (age 55.5 [42.75-65.25], women 48%) and 127 controls (age 57 years [48-63], women 55.1%) underwent comprehensive echocardiographic evaluation and applanation tonometry of the radial and femoral artery. Pulse wave analysis revealed that augmentation pressure, augmentation index (AIx), and heart rate-corrected AIx were significantly lower (median [interquartile range]: 8.75 [4.625-13] vs 11 [6.5-14.5], P = .017; 26.5 [17.5-33.375] vs 30.5 [20.75-37.5], P = .014; and 22.25 [15.125-29.5] vs 27 [20.5-33], P = .008, respectively) in the β-Τm group compared to controls. The left atrial active emptying volume was significantly lower and the isovolumic relaxation time was shorter in the β-Τm group compared to the control group (10.2 [7.4-14.4] vs 12.0 [8.6-15.8], P = .040 and 78 [70-90] vs 90 [70-104], P = .034, respectively). β-Thalassemia minor is associated with favorable pulse wave augmentation indices and left ventricular diastolic function profile in asymptomatic individuals with cardiovascular risk factors.

The emergence and maintenance of sickle cell hotspots in the Mediterranean

Genetic disorders of haemoglobin (haemoglobinopathies), including the thalassaemias and sickle cell anaemia, abound in historically malarious regions, due to the protection they provide against death from severe malaria. Despite the overall spatial correlation between malaria and these disorders, inter-population differences exist in the precise combinations of haemoglobinopathies observed. Greece and Italy present a particularly interesting case study: their high frequencies of beta thalassaemia speak to a history of intense malaria selection, yet they possess very little of the strongly malaria protective mutation responsible for sickle cell anaemia, despite historical migrational links with Africa where high frequencies of sickle cell occur. Twentieth century surveys of beta thalassaemia and sickle cell in Greece, Sicily and Sardinia have revealed striking sickle cell ‘hotspots’ – places where the frequency of sickle cell approaches that seen in Africa while neighbouring populations remain relatively sickle cell free. It remains unclear how these hotspots have been maintained over time without sickle cell spreading throughout the region. Here we use a metapopulation model to show that (i) epistasis between the alpha and beta forms of thalassaemia can restrict the spread of sickle cell through a network of linked subpopulations and (ii) the emergence of sickle cell hotspots requires relatively low levels of gene flow, but the aforementioned epistasis increases the chances of hotspots forming.