Distribution and frequency of beta-thalassemia mutations in northwestern and central Greece

OBJECTIVES

Beta-Thalassemia is a common autosomal recessive disorder resulting from over 200 different mutations of the beta-globin genes. The spectrum of beta-thalassemia mutations in Greece has been previously described in the population of the capital city of Athens, or in beta-thalassemia patients having transfusion therapy. The aim of the present study was to identify the distribution of the most common beta-thalassemia mutations in the population of northwestern and central Greece.

METHODS

The data for this study were derived from a total of 1,130 unrelated subjects including 46 beta-thalassemia major, three beta -thalassemia intermedia and 1,081 carriers identified in our antenatal screening program. beta-Thalassemia mutations were identified by ARMS, DGGE and Reverse Dot Blot.

RESULTS

The most common mutation, IVS-I-110, is followed, in order of frequency, by the mutations Cd-39, IVS-I-1, IVS-II-1, Cd-6, IVS-I-6, IVS-I-5, IVS-II-745, Cd-5 and 44 bp del. IVS-I-110 and Cd-39 frequencies are similar with those found in other Balkan countries. Significant differences in regional distribution were observed. The results showed a clear drift of the distribution of the most frequent IVS-I-110 mutation in the south-north (29.4, 40.0, 44.6 and 61.7%) and the east-west axis (31.8 and 44.6%).

CONCLUSIONS

Population screening and prenatal diagnosis are significantly facilitated by these data. Furthermore, the detailed distribution tables of beta-thalassemia mutations are essential for counseling and extraction of genetic diversity estimates for population genetic studies in other inherited disorders.

The Sp1 COLIA1 gene polymorphism, and not vitamin D receptor or estrogen receptor gene polymorphisms, determines bone mineral density in postmenopausal Greek women

Several genetic polymorphisms are implicated as determinants of bone mineral density (BMD) in postmenopausal women. These include the Sp1 polymorphism of the collagen type I alpha 1 (COLIA1) gene, the FokI and BsmI polymorphisms of the vitamin D receptor (VDR) gene, and the PvuII and XbaI polymorphisms of the estrogen receptor (ER) gene. The relative importance and the independence of these genetic effects have not been studied simultaneously in the same population. We evaluated the effects of these polymorphisms on lumbar spine BMD among 154 postmenopausal Greek women. BMD tended to differ across Sp1 genotypes (mean 0.842 g/cm2 in SS, 0.851 g/cm2 in Ss, 0.763 in ss, age-adjusted p = 0.056), mostly because ss homozygotes had lower BMD (p = 0.018 compared with SS and Ss). No other polymorphisms were associated with BMD in this population (p = 0.53 for FokI, p = 0.94 for BsmI, p = 0.80 for PvuII, p = 0.91 for XbaI). In multivariate modeling, the effect of ss homozygosity was clinically and statistically significant (-0.105 g/cm2, p = 0.013) after adjusting for age, weight, height, hormone replacement use, and the other four polymorphisms. None of the other four polymorphisms was retained as an independent predictor of BMD in a backward elimination model and no significant synergistic effects were observed when gene interactions were tested. When all five polymorphisms are considered simultaneously, the Sp1 COLIA1 polymorphism seems to have the most unequivocal effect on BMD, at least in postmenopausal women.

Genotypes of N-acetyltransferase-2 and risk of bladder cancer: a case-control study

PURPOSE

This study was conducted to examine whether certain slow N-acetylation genotypes could be risk factors for bladder cancer, and the possible association between specific genotypes and the severity of the disease at first diagnosis.

MATERIALS AND METHODS

This case-control study included 89 patients with transitional cell bladder cancer (diagnosed over a period of 21 months) and 147 controls. N-acetyltransferase-2 (NAT-2) genotypes were identified by allele specific polymerase chain reaction (PCR) on peripheral blood DNA samples. The x2 test was used for statistical evaluation to compare the differences observed between patients and controls and the different genotypes with tumor grading and local staging at presentation. Relative, attributable and population attributable risks were estimated for the genotypes found to present a significantly increased frequency for bladder cancer.

RESULTS

A statistically significant difference in the frequency of genotypes was found between the two groups. The patient group had the higher frequency of slow acetylation genotypes (p = 0.0016). Among slow acetylators, homozygotes 341C/341C and compound heterozygotes 341C/857A had the most excessive risk for bladder cancer (p = 0.0041 and 0.0031, respectively). The 341C/341C genotype was found to be associated with more aggressive disease, in terms of tumor grading at presentation (p <0.05).

CONCLUSIONS

According to our data, slow acetylators with 341C/341C and 341C/857A genotypes carry a substantially higher odds ratio (3.73 and 12.46, respectively) for bladder carcinogenesis. Additionally, among the slow acetylators, 341C/341C homozygotes are likely to have a higher risk for more aggressive disease.

Prenatal diagnosis of beta-thalassaemia by coelocentesis

Coelomic fluid and placental tissue were obtained from four women undergoing termination of pregnancy at 7-9 weeks gestation for psychological reasons. All four women and their partners were known carriers of beta-thalassaemia and DNA analysis in their blood identified the mutation carried by each of them. Allelespecific polymerase chain reaction and denaturing gradient gel electrophoresis techniques were used to detect and identify the mutations in the DNA extracted from the coelomic cells and placental tissue. Three fetuses were found to be carriers of either the paternal or maternal mutation, while one was found to be affected by beta-thalassaemia. There was concordance in the results obtained from the chorionic villi and coelomic cells. Amplification of the apolipoprotein B gene variable number tandem repeats (VNTR), in the DNA of the coelomic cells showed normal sagregation of alleles in the fetuses, thus excluding maternal contamination. The results of this study demonstrate that coelocentesis may be a reliable alternative technique for the diagnosis of beta-thalassaemia from as early as 7 weeks gestation.