Análise do polimorfismo TA6/TA7 na região promotora do gene UGT1A1, em pacientes com anemia e traço falciforme de dois hospitais da cidade de Porto Alegre RS

Abstract

Sickle cell disease is a chronic hemolytic anemia, recessive autossomal, caused by a mutation on chromosome 11. This mutation causes a substitution of a valine for a glutamic acid at position six of hemoglobin -chain, leading the formation of hemoglobin S inside the red cells. Gilbert's syndrome is caused by the insertion of a dinucleotide "TA" in the UGT1A1 gene promoter region, causing a reduction in the activity of UDP-glucoronosyl-transferase, the enzyme responsible for bilirubin conjugation. Several authors have described a possible relationship between sickle cell anemia and Gilbert's syndrome, however, consistent data to support this hypothesis are not available in the literature. This study evaluated the dinucleotide TA6 and TA7 in the promoter region of the UGT1A1 gene in patients with sickle cell anemia and sickle cell trait. This study included 65 patients. Sixty one patients had sickle cell trait, 14 were homozygous (TA)6/(TA)6 (19.6%), 32 were homozygous (TA)7/(TA)7 (54%), and 16 heterozygote (TA)6/(TA)6 (26.2%). Between the four patients with sickle cell anemia, three were homozygous for (TA)7/(TA)7 and one heterozygous (TA)6/(TA)7. The results obtained with patients with sickle cell anemia are similar to data described in the literature; however, additional studies are needed to verify if this relationship may interfere with bilirubin levels, especially in patients with sickle cell trait.