No abstract

We used a restriction endonuclease to analyze the beta-thalassemia gene in Sardinia. When we digested human DNA with the restriction enzyme Bam HI, the beta-globin gene split into a 5' portion contained in a fragment of DNA 1.8 kb in length and a 3' portion in a fragment 9.3 kb in length. In some subjects, a variation in the nucleotide sequence affecting the site recognized by this enzyme on the 3' side of the beta-globin gene resulted in a different fragment, 22 kb in length, which contained the 3' portion of the beta-globin gene. In Sardinians without beta-thalassemia, the frequency of the 9.3-kb fragment was 0.67, and that of the 22-kb fragment was 0.33. In contrast, all the beta 0-thalassemia genes were associated exclusively with the 9.3-kb fragment. Thus, the beta 0-thalassemia lesion in Sardinians apparently arose on a chromosome that had the 9.3-kb Bam HI fragment. This observation can be used in prenatal diagnosis of beta 0-thalassemia in Sardina, since demonstration of the 22.0-kb fragment would indicate the normal beta-globin genotype and exclude the beta 0-thalassemia lesion on that chromosome. (N Engl J Med 302:185-188, 1980).

The red cell indices and results of globin chain synthesis in peripheral blood of obligate beta 0 thalassemia (beta 0 thal) carriers (parents of homozygous beta 0 thal children) and beta thalassemia (beta thal) carriers identified during mass screening are reported. Red cell indices were similar in obligate beta 0 carriers and in carriers diagnosed during mass screening. However there was a higher incidence of anemia in female obligate beta 0 thal carriers. In Sardinia the beta 0 thal carrier showed the usual hematological characteristics of the high Hb A2 beta thal carrier with microcytosis, hypochromia, reduced osmotic fragility; Hb F greater than 1% was found in 30% of the carriers. With MCV, MCH, osmotic fragility test (OFT) and Shine and Lal discriminant function we found 3.5%, 1.5%, 3.5% and 4.0% respectively false negatives in carrier identification. A part from one subject, all obligate carriers had elevated Hb A2 levels. The alpha/beta ratio in obligate carriers (mean +/- SD) was 1.83 +/- 0.26 (N = 30).

The aim of this study was to describe the mutational spectrum of hemoglobinopathies during the period 1988-2015 in Umbria, Central Italy, which has never been considered endemic for these conditions. Twenty-four different β-globin gene mutations were identified in 188 patients and eight different α-globin gene mutations in 74 patients. Sixty percent β-thalassemia (β-thal), 85.0% sickle cell disease, 44.0% Hb S (HBB: c.20A>T)/β-thal and 85.0% compound heterozygotes for hemoglobin (Hb) variant-carrying patients were diagnosed or molecularly characterized in the last 3 years. Moreover, most homozygous or compound heterozygous patients (84.5%) came from foreign countries, while only 15.5% were of Italian origin. These data are in accordance with the increasing foreign resident population in Umbria, which has nearly doubled in 10 years (2004-2014). Different from β-globin gene variations, no increasing trend in α defects was observed in our study cohort. Consistently, 58.0% of patients have an Italian origin, suggesting no broad influence of foreign migration in the α-globin genes genetic background. As few defects are prevalent in each country of origin or ethnic group, their knowledge may provide a proper strategy for the identification of mutations in immigrant individuals in a non-endemic region and be important for carrier identification and prenatal screening.

Prenatal diagnosis with globin chain synthesis analysis on fetal red blood cells concentrated by NH4Cl-NH4HCO3 differential lysis of maternal cells (Orskov lysis) was carried out in 27 pregnancies at risk for beta thalassaemia and one at risk for sickle cell beta0 thalassaemia. The beta/gamma globin chain synthesis ratio was also determined after anti-i-differential agglutination (12 cases), in almost pure fetal samples (sic cases) and by extrapolation (one case). Differential lysis permitted the study of samples drawn by placental aspiration containing as little as 3.2% fetal red blood cells. There was no consistent difference between the beta/gamma ratios observed after differentail lysis and those determined after the use of the other approaches. A presumptive diagnosis of homozygous beta thalassaemia was made in nine cases. All but one of these pregnancies was terminated. The absence of beta chain synthesis was confirmed by the study of fetal blood after abortion in four cases with suitable samples. Of the remaining pregnancies, six proceeded to term and non-homozygous infants were delivered. The others are still in progress. No fetal loss occurred. Orskov lysis seems to be a very reliable method for prenatal diagnosis of beta chain abnormalities. Moreover it can minimize the number and duration of placental aspirations required and thus the risk to the fetus.