Biomedical subjects

G Deidda

Publications and source records attributed to G Deidda.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Detection of alpha-globin gene disorders by a simple PCR methodology.

BACKGROUND: alpha thalassemias are very common in all thalassemic areas; however, complete knowledge of the phenotypic, genotypic and epidemiological features of these thalassemias has not yet been achieved for a number of reasons: the frequent absence of a thalassemic hematologic picture, the lack of a specific characteristic comparable to the Hb A2 increase for beta thalassemias, and the almost complete homology between the two alpha genes. METHODS AND RESULTS: A new set of PCR techniques, each based on primer(s) specific for a particular type of alpha globin gene disorder, has been devised in our laboratory. The procedures are simple, and non-radioactive. They lead to the identification of all alpha globin disorders common in the Mediterranean area [-alpha 3.7, -alpha 4.2, alpha Hphl, alpha Ncol, --MED, -(alpha)20.5, alpha alpha alpha anti3.7]. The electrophoretic patterns specific for the main alpha globin alterations as observed with this set of techniques, are presented. CONCLUSIONS: Owing to their advantageous properties, these techniques are suitable for precise molecular characterization of the numerous subjects selected through mass population screenings.

DNA Primers↗

PubMedDate not supplied

Silent thalassemias: genotypes and phenotypes.

BACKGROUND AND OBJECTIVE: Current application of molecular biology techniques to the study of the DNA of globin genes has confirmed the existence of silent alpha and beta thalassemias; which had already been reported on the basis of red blood cell parameters and family studies. The present work was aimed at analyzing all the aspects of the phenotype of the most common varieties of silent thalassemia. MATERIALS AND METHODS: Groups of heterozygous carriers of these varieties were examined using established techniques that determined all hematologic, hemoglobin (electrophoresis and measurement of Hb A2 and Hb F levels), and globin synthesis (evaluation of the alpha/beta ratio) parameters. Furthermore, all subjects underwent a complete molecular study of the alpha and beta globin genes by means of the ARMS, SSCP, DGGE, PCR and Southern blotting techniques. RESULTS: 1) The -101 C-->T mutation of the promoter of the beta globin gene shows a normal hematological picture with the Hb A2 level often slightly raised and the alpha/beta globin synthesis ratio slightly greater than 1; 2) beta + thalassemia resulting from the IVS II 844 C-->G mutation has a phenotype that is even closer to normal; 3) -alpha 3.7 deletion type I usually has a totally silent phenotype; 4) the alpha Ncol mutation almost always gives rise to a sub-silent phenotype if it is located on gene alpha 2 and to a silent phenotype if it is found on gene alpha 1; 5) alpha + thalassemia due to the alpha 2 Hphl mutation displays a sub-silent phenotype in some cases and a silent one in others; 6) triplication of the alpha genes gives rise to a phenotype that is quite similar to that of the -101 C-->T mutation of the promoter of the beta globin gene, namely one that is very often silent. INTERPRETATION AND CONCLUSIONS: Many of these silent varieties (beta + thalassemia due to the -101 C-->T mutation; alpha + thalassemia from a deletion or point mutation of an alpha gene; alpha alpha alpha triplication) are quite frequent in the overall group of thalassemias. It is therefore important for the operators in the field of thalassemia diagnosis to possess exact knowledge of them especially in order to prevent thalassemia major.

Adolescent↗

PubMedDate not supplied

Phenotypes of individuals with a beta thal classical allele associated either with a beta thal silent allele or with alpha globin gene triplication.

BACKGROUND AND OBJECTIVE: beta thalassemia intermedia has its origins in compound heterozygosity for many different beta thal defects or in an interaction of a beta thal defect with altered alpha cluster. Two specific genetic associations (beta thal/beta(+) -101 C-->T and beta thal + alpha alpha alpha or alpha alpha alpha alpha) have been described in recent years as being determining a phenotype similar to that of simple beta thal heterozygote or, alternatively, a clinical picture of thalassemia intermedia. METHODS: A detailed study on this subject was carried out on 55 patients divided into 2 groups. Group I consisted of 20 patients, 17 of whom (Group Ia) had a beta thal/beta(+) -101 C-->T genotype and 3 (Group Ib) had a beta thal/beta IVS II-844 C-->G genotype. Group II consisted of 35 patients with beta thal association + alpha alpha alpha or alpha alpha alpha alpha. The methods of study have already been described in a previous issue. RESULTS: Thirty percent of group Ia and 25% of group II were virtually asymptomatic, while the others presented the thalassemia intermedia phenotype. This second phenotype is generally milder in patients of group I and even less so in those of group II. In the former there is a higher level of HbF; in the second there is more marked alpha/beta + gamma globin synthesis imbalance. The severity of the phenotype has no connection with that of the beta thal defect. The patients of group Ib all presented thalassemia intermedia. INTERPRETATION AND CONCLUSIONS: The definite clinical pictures of groups I and II are quite common in the Italian population and should therefore be well understood, especially for proper application of preventive measures against thalassemia major.

Adolescent↗