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A Iolascon

Publications and source records attributed to A Iolascon.

141 records · Page 8Linked to original sources
PubMedDate not supplied

Hereditary spherocytosis (HS) due to loss of anion exchange transporter.

BACKGROUND: Hereditary spherocytosis encompasses a heterogenous group of inherited disorders due to alteration of r.b.c. surface/volume ratio. Spectrin deficiency is the most common observed defect. We analyzed a case of HS associated with band 3 deficiency without spectrin reduction. METHODS: In the study of a family originating from southern Italy, we show that a 20% deficiency of band 3 with normal spectrin content may be responsible for dominantly inherited hereditary spherocytosis (HS). The proband is a 12 years old girl consulting for jaundice, chronic anaemia and splenomegaly. Her mother had a similar haematologic phenotype. RESULTS: Electrophoretic analysis of erythrocyte membrane proteins showed a deficiency in band 3 protein. Band 3 protein chymotryptic fragments, deglycosylated band 3, and its isolated cytoplasmic domain, all displayed normal electrophoretic migrations. Furthermore, the tryptic peptides profile of the cytoplasmic domain of the protein did not demonstrate any abnormality, nor did the amino acid composition of the peptides. Analysis of the membrane proteins during erythrocyte ageing, evaluated in density-fractionated red cells, showed that band 3 content was normal in the lighter fraction, whereas in the denser fraction band 3 deficiency was more pronounced than in membranes from non fractionated red blood cells. CONCLUSIONS: This case describes HS due to anion exchange transporter deficiency. Our results on fractioned red cells support the hypothesis that the defect was probably due to a band 3 protein loss during cell ageing and not to a primitive quantitative defect.

Adult↗
PubMedDate not supplied

Molecular pathology of inherited erythrocyte membrane disorders: hereditary spherocytosis and elliptocytosis.

Hereditary spherocytosis and elliptocytosis are common genetic defects of the red blood cell membrane skeleton. In recent years rapid advances have been made in the knowledge of the protein structure and assembly of the cytoskeleton. Thanks to the wide use of protein analysis methods several alterations have been discovered in functionally important domains of the different cytoskeletal proteins in these diseases. The cloning of cDNA for the majority of the cytoskeletal proteins allows us to begin elucidating some of these defects at the DNA level. This paper will review the effects of recent advances upon: cytoskeleton structure and assembly; molecular pathology of spherocytosis, elliptocytosis and pyropoikilocytosis.

Adult↗
PubMedDate not supplied

Molecular heterogeneity of hereditary elliptocytosis in Italy.

BACKGROUND: Common HE is the most prevalent clinical form of hereditary elliptocytosis; its clinical findings vary considerably, ranging from an asymptomatic carrier state to a severe, even life-threatening hemolytic disorder. Structural modification and reduction of 4.1 protein, or abnormalities at the spectrin self-association site could lead to elliptocytes. METHODS: Sixty-one Italian HE patients belonging to 28 families were studied. Analysis of red blood cell cytoskeleton was performed by means of SDS-PAGE, and spectrin dimer percentage was assessed by non denaturing polyacrylamide gel electrophoresis. Limited tryptic digestion of spectrin was employed in patients showing an abnormal dimer increase, and the amount of abnormal alpha I peptide was estimated. Molecular defects were detected by means of PCR of alpha and beta spectrin genes and direct sequencing of genomic DNA. RESULTS: We found a very heterogeneous spectrum of cytoskeletal alterations: 18 (29%) subjects showed partial protein 4.1 deficiency, whereas 31 (51%) displayed an increased amount of spectrin dimers; we were not able to detect any alteration in 12 (20%) HE patients. Patients enrolled in this study were widely distributed throughout Italy. CONCLUSIONS: The subgroup of HE patients related to 4.1 deficiency is homogeneously asymptomatic, whereas forms due to disruption of the spectrin tetramerization site are very heterogeneous, and clinical severity appears to be related to spectrin dimers and especially to spectrin content. These two parameters in turn are related to the presence of a low expression alpha allele in trans and to the degree of disruption of head-to-head contact between alpha and beta chains.

Adolescent↗
PubMedDate not supplied

[The prognostic effect of amplification of the MYCN oncogene in neuroblastoma. The preliminary results of the Italian Cooperative Group for Neuroblastoma (GCINB)].

Of 567 children with neuroblastoma diagnosed between November 1984 and May 1993 in 21 Italian institutions, 235 (41%) have been evaluated for MYCN oncogene amplification. The amplification (3 or more copies of the gene) was found in 39 patients (17%) and was more frequent in patients aged more than one year, abdominal primary site of the tumor, advanced stages, normal urinary excretion of vanillylmandelic acid (VMA), and high level of LDH, NSE and ferritin. The five-year survival of the 235 patients (62%) was significantly better in patients with normal copy number of MYCN (69% versus 29%). By correlating genomic amplification with clinical and biochemical characteristics, MYCN amplification was found associated with a worse prognosis even when patients were subdivided for age (under and above one year), disease extension (localized operable, localized but inoperable, and disseminated) with exception for Stage IV-S, VMA and homovanillic acid excretion, serum levels of NSE and ferritin, but not of LDH. These data confirm the unfavourable prognostic meaning of MYCN amplification, but are unable to define if it represents a new independent variable.

Adolescent↗
PubMedDate not supplied

Cell cycle regulation and human leukemias: the role of p16INK4 gene inactivation in the development of human acute lymphoblastic leukemia.

Recent advances in cancer biology have clearly demonstrated that the development of neoplasms as well as their progression are strictly linked to the alteration of molecular mechanisms controlling the cell division cycle. Among these mechanisms the functional inactivation of two important tumor suppressor genes, namely RB1 and p53, has been widely recognized as a pivotal step in human cancerogenesis. In addition to such well-known genes, a new tumor suppressor gene, mapping on chromosome 9p21, has recently been identified and cloned. Several findings suggest that its loss of function is involved in the initiation and/or progression of an enormous number of different malignancies. This gene, named p16INK4, codifies for a small protein capable of binding to, and thus of inhibiting, some specific cyclin-dependent threonine-serine kinases that represent key enzymatic activities essential for the G1-S transition in mammalian cells. This review will summarize some aspects of the cell cycle control mechanisms, with major emphasis devoted to the role played by this recently characterized inhibitor and to the possible linkage between its inactivation and cancer formation. In particular, we will discuss these aspects in the light of the role of p16INK4 gene inactivation in the development of human acute lymphoblastic leukemias. Indeed this gene seems to be the first, and so far the only tumor suppressor gene consistently altered in specific acute hematological malignancies. Finally, future trends in the investigation of cell cycle control and leukemogenesis will be analyzed.

Cell Cycle↗
PubMedDate not supplied

Congenital dyserythropoietic anemia type II: molecular basis and clinical aspects.

Congenital dyserythropoietic anemia of type II (CDA II) is a rare disorder, usually present in childhood, with a clinical picture of chronic anemia of mild to moderate degree, splenomegaly and intermittent or persistent jaundice. It is transmitted by autosomal recessive inheritance and is characterized by the presence of a large number of multinucleate and binucleate erythroblasts in the bone marrow and typical morphological abnormalities of the membrane of circulating erythrocytes. SDS-PAGE of red blood cell membrane proteins shows a narrower aspect and a faster migration of band 3 (anion exchange transporter). This aspect is consistent with decreased glycosylation of this protein. The genetic mutations responsible for the glycosylation defect in CDA II have not yet been identified. Analysis of carbohydrate structures and biochemical data indicate that the activity of either GnT II or alpha-Man II is reduced in different families, suggesting that the disease is genetically heterogeneous. Molecular cloning of the GnT II and alpha-Man II DNA sequences has allowed direct investigation of the genetic mutations underlying the glycosylation defect in CDA II patients to begin.

Anemia, Dyserythropoietic, Congenital↗
PubMedDate not supplied

Apparently normal ankyrin content in unsplenectomized hereditary spherocytosis patients with the inactivation of one ankyrin (ANK1) allele.

The study of erythrocyte membrane protein concentration by polyacrylamide gel electrophoresis (PAGE) is the first step in approaching the primary molecular defect in hereditary spherocytosis (HS). Normal or greater than normal protein 2.1 levels were found in ten unrelated HS patients showing the inactivation of one ankyrin allele. Erythrocyte membranes from the same patients, once splenectomized, showed a homogeneous degree of protein 2.1 reduction. Thus protein 2.1 levels could misleadingly appear normal due to the high number of circulating reticulocytes. To calculate the true ankyrin level using PAGE and consequently to avoid mistakes in studying a mutated gene, a simple equation, based on the number of reticulocytes, was developed.

Algorithms↗
PubMedDate not supplied

Resistance to activated protein C as a risk factor of stroke in a thalassemic patient.

It is well known that thalassemic patients exhibit an increased frequency of thrombotic events. Most individuals with resistance to activated protein C (APCR) are the result of a point mutation replacing Arg 506 with Gln in the factor V aminoacidic sequence (factor V Leiden). Recently APCR has been shown to account for up to 50% of cases of thrombophilia. In this report, we describe a 10 year old thalassemic intermedia patient heterozygous for Factor V R506Q who developed a stroke following transfusion. Coagulation laboratory values were all within the normal range and there was no evidence of a lupus anticoagulant. Computerized brain tomography showed an ischemic area in the left temporo-parietal region. At follow-up, plasma from the patient demonstrated APCR and molecular diagnostic testing revealed heterozygosity for factor V R506Q. We suggest that the heterozygosity for factor V Leiden could increase the thrombotic risk in thalassemia intermedia. We believe it may be beneficial to screen all intermedia thalassemic patients for APCR especially before starting a transfusional regimen.

Blood Coagulation Disorders↗