Student screening for inherited blood disorders in Bahrain

In Bahrain and neighbouring countries inherited disorders of haemoglobin, i.e. sickle-cell disease, thalassaemias and glucose-6-phosphate dehydrogenase (G6PD) deficiency, are common. As part of the National Student Screening Project to determine the prevalence of genetic blood disorders and raise awareness among young Bahrainis, we screened 11th-grade students from 38 schools (5685 students), organized lectures and distributed information about these disorders. Haemoglobin electrophoresis, high performance liquid chromatography, blood grouping and G6PD deficiency testing were performed. Prevalences were: 1.2% sickle-cell disease; 13.8% sickle-cell trait; 0.09% beta-thalassaemia; 2.9% beta-thalassaemia trait; 23.2% G6PD deficiency; 1.9% G6PD deficiency carrier. Health education, carrier screening and premarital counselling remain the best ways to reduce disease incidence with potentially significant financial savings and social and health benefits.

[Genetic hemoglobin diseases. Prevention at centers for family planning and education of maternal-child protection in Marseille]

OBJECTIVES

Diseases due to inherited hemoglobin disorders represent serious medical, social, and economic problems in the region of Marseille. The only effective treatment for such diseases is allogenic bone marrow transplantation. About 200 patients with either thalassemia, sickle cell or sickle cell-beta thalassemic diseases are regularly seen in local hospitals. All of these patients come from parts of the world where genetic hemoglobin disorders are endemic.

METHODS

At this time, the only approach for reducing the number of affected children born is preventive. This depends upon education, the detection of carriers, genetic counselling and sometimes, prenatal diagnosis. We have organised a program of prevention supported by a grant from the DISS (Direction des Interventions Sociales et Sanitaires) in the context of visits made to the PMI (Prevention Maternelle et Infantile). This initiative concerns women presenting for consultations for three reasons: for a prenuptial check-up, for a pregnancy, and for prescription of contraceptives.

RESULTS

In each of these three situations a check-up is obligatory and, for natives of countries where hemoglobin disorders are common, a hemoglobin test is recommended. If this test reveals an abnormality, the partner or husband is also tested, if he is willing. Couples who are both carriers are given genetic counselling.

CONCLUSION

This preventive initiative has yielded valuable results so we hope to follow-up on the approach and extend it to other centers. Such screening, based upon the geographic origins of patients, can be implemented in the course of a consultation by any doctor.

Screening for hemoglobins S and C in newborn and adult blood with a monoclonal antibody in an ELISA procedure

To facilitate the screening of blood for the presence of hemoglobins S or C, we devised an enzyme-linked immunoassay (ELISA). The ELISA procedure incorporated a murine monoclonal antibody (mAb), beta s-1, which recognized both Hb variants but did not react with Hb A, Hb A2 or Hb F. Hemoglobins in cord or adult hemolysates were coated on the surface of wells of polystyrene microtiter plates and treated with beta s-1 mAb, followed by goat anti-mouse IgG conjugated with horseradish peroxidase. After addition of tetramethylbenzidine substrate solution, a deep blue color developed, signifying the presence of Hb S or Hb C. The beta s-1 mAb ascites fluid could detect purified Hb S and Hb C when diluted to over 1/512,000 and cord blood hemolysates containing Hb/S or Hb C when diluted to 1/128,000. Although maximal reactivity was achieved using undiluted hemolysates, the ELISA system could easily detect Hb S and Hb C in cord blood hemolysates when diluted 10(-4). The sensitivity of the ELISA was 1%, which exceeds the lowest quantities of these variants normally found in cord blood. In addition, we found that the ELISA procedure was suitable for detecting Hb S/Hb C in whole blood as well. The entire assay could be conducted on multiple samples in less than 1 h, thus providing a specific, sensitive, rapid and simple screening technique for Hb S and Hb C in cord or adult blood.