Dissertação
Estudo da prevalência de hemoglobina S em doadores de sangue na região de Santa Maria-RS e aconselhamento genético familiar
Fecha
2009-02-18Autor
Giovelli, Letícia Loi
Institución
Resumen
The Sickle Cell Anemia is the most common monogenic hereditary disease in the
world. The cause of this disease is a changing point in the position six of the beta globin
gene for hemoglobin, changing the glutamic acid by a valine, with consequent physical and
chemical modification of the molecule and result in abnormal hemoglobin, called
hemoglobin S (HbS). The sickle cell trait characterized the asymptomatic carriers,
heterozygous (HbAS), which does not present the disease or have abnormalities in the
number and shape of red blood cells. Carriers in this situation is very frequent, in Brazil can
reach 1 to 5% of the general population and from 6 to 10% of African descent, and the
greater importance of their diagnosis is for genetic counseling of the affected population.
This study aimed to determine the prevalence of sickle cell trait blood donors in the region
of Santa Maria, promoting a genetic counseling reporting on reproductive risks, compare
the most widely used screening methods for the detection of Hb S in blood banks, quantify
abnormal hemoglobin found through quantitative electrophoresis and confirmed by
molecular analysis. The study of the prevalence of Hb AS in blood banks was carried out
with the screening of 26,071 blood donors who presented to the banks of blood from the
University Hospital of Santa Maria (HUSM), Charity Hospital Dr. Astrogildo of Azevedo and
Health House. Genetic counseling was conducted through individual guidance with
explanations about the condition of sickle cell trait and awareness of genetic risk. To
compare the methods of screening for detection of Hb S was analyzed a total of 4,108
donors by the methods of solubility, gel-centrifugation Diamed ID-HbS and hemoglobin
electrophoresis qualitative in cellulose acetate. Of the total donors, 88 (0.34%) had results
changed with the presence of Hb S. In genetic counseling, 57 (85%) blood donors with
sickle cell trait came to attend counseling. In the comparison of methodologies, 23 donors
(0.56%) had Hb S and 2 donors (0.05%) had Hb C. The frequency for the presence of Hb S
in blood donors by the electrophoresis of hemoglobin was 23 (0.56%), the solubility test
was 22 (0.53%) and gel-centrifuge test was 20 (0.49%). The solubility test showed 95.6%
sensitivity and gel-centrifuge test Diamed ID-HbS showed 86.9% sensitivity when
compared with the electrophoresis of hemoglobin and both proved to be 100% specific.
This study showed that the prevalence of 0.34% of Hb AS is a value found to be very close
to the reality of the region to present a very significant number of donors tested. The
solubility test showed good specificity and sensitivity demonstrating to be a good method of
choice for application in screening of Hb S in blood donors.