Subclinical autonomic dysfunction in patients with ß-thalassemia.

We electrophysiologically evaluated the autonomic function (AF) in a consecutive series of patients with beta-thalassemia and in normal individuals. Six quantitative autonomic function tests (AFTs) were used: tilt test, hand grip test and sympathetic skin response for sympathetic function; R-R interval, inspiration-expiration difference and 30/15 ratio for parasympathetic function. The prevalence of impaired AF was higher in beta-thalassemia patients (13%, n = 5) than in control subjects (0%, n = 0; p = 0.026). Subclinical autonomic dysfunction appeared to be more prevalent in beta-thalassemia patients compared to controls in our series. Further independent validation of this finding is required in larger cohorts of beta-thalassemia patients.

G gamma-196 C-->T, A gamma-201 C-->T: two novel mutations in the promoter region of the gamma-globin genes associated with nondeletional hereditary persistence of fetal hemoglobin in Greece.

The increased level of fetal hemoglobin in nondeletional hereditary persistence of fetal hemoglobin (nd-HPFH) is associated with several single base substitutions in the promoter region of either the (G)gamma- or the (A)gamma-globin genes. In this study, we report two new forms of nd-HPFH found in two unrelated Greek adults with high HbF production (8.6% and 10.2% respectively) and positive for the (G)gamma-158 C-->T substitution. Scanning by DGGE analysis and direct sequencing of the gamma-globin gene 5' promoter region revealed the presence of a (G)gamma-196 C-->T in the first case and an (A)gamma-201 C-->T in the second. These mutations seem to reactivate gamma-genes and cause their high expression in the adult period.

The molecular heterogeneity of beta-thalassemia in Greece.

Beta-thalassemia is the most predominant genetic defect in Greece. In this study, we investigated the heterogeneity and the frequency of beta-thalassemia mutations among 3796 heterozygotes detected in the course of DNA based diagnoses. The diagnostic strategy included Denaturing Gradient Gel Electrophoresis (DGGE), Allele Specific Oligonucleotide Hybridization (ASO), GAP PCR, Restriction Enzyme (RE) analysis and direct sequencing and led to 100% identification of the underlying molecular lesion. Six out of 33 different beta-globin defects identified accounted for more than 91.4% of the total beta-thalassemia chromosomes in Greece. The beta-globin gene mutations cd29 C-->T, IVS-I-2 T-->C, IVS-I-5 G-->T, cd37 G-->A and poly A Kurdish AATAAA-->AATAAG are for the first time reported in Greece, whereas cd7 GAG-->TAG is a new beta(0)-thalassemia mutation detected in an adult man from Albania residing in Greece. Three DNA single nucleotide polymorphisms (IVS-I-85 T-->C, IVS-I-91 C-->T and IVS-I-108 T-->C) were also revealed; among these, IVS-I-85 T-->C and IVS-I-91 C-->T are new and described for the first time worldwide.

A comparative study of Greek nondeletional hereditary persistence of fetal hemoglobin and beta-thalassemia compound heterozygotes.

The coexistence of beta- and gamma-globin gene mutations in the compound heterozygous state presents a rare in vivo model that provides important data on gene regulation of clinical interest. In this unique comparative study we present the hematological, biosynthetic, and molecular data from six adult compound heterozygotes for the Greek nondeletional hereditary persistence of fetal hemoglobin (nd-HPFH, Agamma-117 G-->A) and four frequent beta-thalassemia mutations (IVS I-110 G-->A, Cd 39 C-->T, IVS I-1 G-->A, and IVS I-6 T-->C) found in the Hellenic population. Fetal hemoglobin (HbF) levels were found to be considerably higher (25-50%) than in 19 Greek nd-HPFH heterozygotes (HbF=9.7+/-1.7%) and, interestingly, to depend on the type of the respective beta-thalassemia mutation, in trans to the nd-HPFH allele. All cases presented a typical beta-thalassemia heterozygote's phenotype despite the increased HbF and the normal HbA2 levels, as indicated by both the hematological indices and the biosynthetic ratios. These data were compared with those from two unique cases of Greek origin: a homozygous case of the Greek nd-HPFH and a compound heterozygote with HbS. Our data suggest that in these compound heterozygous cases the beta-thalassemic chromosome indirectly determines the final outcome of the gamma- and of the in cis beta-globin gene expression, most likely at the post-transcriptional level.