Importance of molecular biology in the characterization of beta-thalassemia carriers.

OBJECTIVES The term beta-thalassemia includes all those hereditary disturbances of the hemoglobin (Hb), transferred trough a recessive autosomal mechanism, due to a reduced or else defective synthesis of beta globin sequences. The aim of this paper is to highlight as sometimes the only biochemical diagnosis is not exhaustive and a molecular diagnostic widening is necessary to detect the genetic deficiency that is the reason of the beta-thalassemic trait. CASE REPORT AND RESULTS To improve this theory the following clinical case is reported: a 29 years old girl that was 11 weeks pregnant addressed us to receive the prenatal screening test related to the first three-month pregnancy period. The biochemical and hematological tests highlighted that Mrs. D.F. was a carrier of the beta-thalassemic trait, (MCV 63fl decrease, MCH 30pg, HbA2: 4.4 increase, HbF:1.5 increase, red blood cells 5.92 x 10(6)/ul and Hb 12.4 g/dl), that has been confirmed trough our molecular analysis (genotype: beta+IVS1.110 G --> A in heterozigosys). More difficult to be realized was the case of Mr. B.A.: he showed an uncertain hematological picture labeled as "compatible with a alpha-thalassemia picture" (MCV 62.9fl decrease, MCH 21.4pg decrease, HbA2: 2.7, HbF: 1.0, red blood cells 5.33 x10(6)/ul, Hb 11.4 g/dl decrease). This picture revealed difficult to be understood because of the regularity of HbA2 (2.7%) that was in contrast with the value of the MCV (62.9). In situation like this only the molecular diagnosis allows correctly highlighting the specific typology of thalassemia the subject is carrier of. As a matter of fact the molecular analysis excluded the possibility that Mr. B.A. was a alpha-thalassemia carrier and pointed out that he was a healthy carrier of beta-thalassemia (genotype beta degrees 39C --> T in heterozigosys). In the light of what has been explained above, the couple has been informed about risks to beget child suffering from beta-thalassemia and together with the married couple has been decided to work out a prenatal diagnosis through a sample of chorionic villus. DISCUSSION AND CONCLUSIONS The identification of these particular cases fixes important implications about the prenatal diagnosis approach. The correct characterization of the healthy carrier is absolutely necessary with a subsequent study in depth of the partner's situation. It is important to highlight the importance of a careful study of hematological parameters and a widespread and correct information about clinical implication connected to the complications of the beta-thalassemia. As to this subject, the molecular study of the defect of the gene let to point out couples that run the risk of beta-thalassemia and to develop an exhaustive and correct information about the possibility to beget children suffering from beta-thalassemia. If two carrier partners wish to have children they can chose among the following possibilities: they can be well informed about the risk and accept the possibility to beget a child suffering from beta-thalassemia, they can give up the idea of having children or they can decide to beget children however but to avoid the possibility that the same suffers of thalassemia they can ask for a prenatal diagnosis.