Hb J-Cordoba [alpha 2A beta 2(95)(FG2)Lys----Met]. A new Hb variant found in Argentina

Permanence or change? The meaning of genetic variation

Selected aspects of the evolutionary process and more specifically of the genetic variation are considered, with an emphasis in studies performed by my group. One key aspect of evolution seems to be the concomitant occurrence of dichotomic, contradictory (dialect) processes. Genetic variation is structured, and the dynamics of change at one level is not necessarily paralleled by that in another. The pathogenesis-related protein superfamily can be cited as an example in which permanence (the maintenance of certain key genetic features) coexists with change (modifications that led to different functions in different classes of organisms). Relationships between structure and function are exemplified by studies with hemoglobin Porto Alegre. The genetic structure of tribal populations may differ in important aspects from that of industrialized societies. Evolutionary histories also may differ when considered through the investigation of patrilineal or matrilineal lineages. Global evaluations taking into consideration all of these aspects are needed if we really want to understand the meaning of genetic variation.

beta-Thalassemia and hemoglobin types in Argentina: determination of most frequent mutations

In order to know the spectrum of beta-thalassemia alleles and other mutations affecting the beta-globin gene, we analyzed the hemoglobin abnormalities in 24 patients from the Province of Cordoba in Argentina. Molecular screening of samples was performed by the polymerase chain reaction (PCR), using six sets of oligonucleotides to amplify fragments encompassing the whole beta-globin coding region and splice junctions, as well as the promoter and 3' untranslated regions. The altered fragments were determined by denaturing gradient gel electrophoresis (DGGE), and the corresponding mutations were identified by restriction enzyme analysis or by direct sequencing of PCR products. Using this approach, three different beta-thalassemia mutations were detected, codon 39 (C-->T), IVS-1-110 (G-->A), and IVS-1-1 (G-->A), and also the hemoglobin S trait. This is the first report of beta-thalassemia mutations described in Argentina. Our results show that these mutations are similar to those found in Spain and Italy, possibly due to the important Mediterranean migratory stream received in our country, and could be important for prenatal diagnosis of these diseases in Cordoba, Argentina.

Haemoglobin Köln as de novo mutations in Sweden: diagnosis by PCR and specific enzymatic cleavage

Three independent cases of chronic haemolytic anaemia in Sweden have recently been demonstrated to be due to the unstable haemoglobin variant Hb Köln. The patients, all of whom have partially compensated chronic haemolytic anaemia, presented with aggravated haemolysis during acute infections in childhood. In one case, acute B19 parvovirus infection induced an aplastic crisis. The substitutions all seem to have occurred as de novo mutations. Diagnosis was based on haemoglobin instability testing and isoelectric focusing of haemoglobin dimers. The final identification procedure for the substitutions included extraction of DNA from whole blood, polymerase chain reaction (PCR) amplification of parts of the beta-globin gene and nucleotide sequencing of the resulting material, or studies of restriction length polymorphisms (RFLPs) using the restriction endonucleases Mae II or Nla III. The use of PCR-RFLP is recommended as a valuable tool for diagnosing Hb Köln.