G gamma and A gamma globin chains separation and quantitation by isoelectric focusing.
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Biomedical subjects
Publications and source records attributed to C Camaschella.
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Isoelectric focusing, cellulose acetate electrophoresis, and carboxymethylcellulose chromatography in the presence of Nonidet P-40 allow the separation of pure gamma chains into two fractions. Amino acid analysis of their cyanogen bromide fragment 3 (gamma CB3) identifies these fractions as the separated G gamma (Gly-136) and A gamma (Ala-136) globin chains. Fingerprint and amino acid analyses of the gamma Tp9 tryptic peptide from the purified A gamma and G gamma fractions from two different patients demonstrate that the commonly occurring gamma Sardinia variant (gamma 75 isoleucine leads to threonine), also known as T gamma chain, has alanine in position 136. From this analysis we suggest that the T gamma gene is an allele of the A gamma locus (A gamma Sardinia) rather than a third gamma locus.
Hematological data, biosynthetic studies and gamma-chain structure of three heterozygotes for HPFH Greek type and of two heterozygotes for both HPFH and beta-thalassemia are reported. In the HPFH heterozygotes, hematological data were normal and globin chain synthesis balanced, while subjects carrying both HPFH and beta-thalassemia presented a thalassemic picture and the same degree of alpha/non-alpha-chain imbalance as the beta-thalassemia carrier belonging to the same family. The gamma-chain composition studies showed only the presence of Agamma-chains in HPFH; in the association HPFH/beta-thalassemia also some Ggamma and Tgamma were found. The mechanisms determining the high production of Hb F in the association HPFH/beta-thalassemia are discussed.
We report the case of an Italian infant girl from Polesine (Po delta region in northern Italy) who was heterozygous for Hb Hasharon and alpha-thalassemia, did not synthesize any normal HbA, and had 3% HbH on electrophoresis. Hematologic and biosynthetic studies on Hb Hasharon carriers of the propositus' family suggest the possibility that the Hb Hasharon gene is linked to an alpha-thalassemia gene. On the other hand, in the Askenazy carriers of Hb Hasharon, Hb Harsharon is probably linked to a normal alpha gene. In comparing Hb Hasharon's behavior with that of other alpha variants, particularly HbG Philadelphia, frequent recombinations between alpha structural genes were suggested. The possible identity between the single alpha locus and the alpha2-thalassemia genotype is discussed.
The results of 38 cases of laparotomy with splenectomy in Hodgkin's disease are presented. After describing the results obtained, and modifications due to preoperative classification of Hodgkin's disease, the diagnosis and surgical treatment are shortly discussed.
A new type of hemoglobin F, in which isoleucine in position 75 (E 19) of the gamma chain is replaced by a threonine residue, has been found in 29 out of 32 homozygotes for beta thalassemia. The amount of this hemoglobin ranges from traces to 40% of the total Hb F. The same gamma75 Thr chain is also present in the Hb F of 40% of normal newborns and premature infants examined, of one 14-week-old fetus and in one out of 3 patients with aplastic anemia and raised levels of Hb F. Our results strongly suggest that the synthesis of this new chain is under the control of a gamma gene nonallelic with those coding for Agamma and Ggamma chains.
The haematological and clinical data in 254 Italian subjects with beta-thalassaemia trait are reported. 46% of the patients were anaemic, 40% complained of weakness, 19% showed enlargement of the spleen and 10% enlargement of the liver. The haemoglobin levels ranged from 8 to 15.5 g/dl with a normal distribution and a mean of 12.73 for males, 10.93 for females and 11.34 for children (4-15 years). Reticulocyte counts and serum bilirubin levels were slightly increased and both showed a statistically significant relationship with haemoglobin levels. The serum iron level was increased in 27% and decreased in 6% of the cases. Haemoglobin A2 concentrations ranged from 3.5% to 8% with a normal distribution and a mean of 5.37; Hb F values were less than 1% in 36% and varied from 1 to 14% in the remainder. Red cell osmotic fragility was decreased in all but 6% of the subjects: low MCV, MCH and MCHC values were observed in 75%, 86% and 10% respectively. A comparison is made between the data and those obtained by other workers.
Erythrocyte survival, fecal stercobilinogen, and the alpha/beta-chain synthesis ratio in recticulocytes and bone marrow (six cases only) were determined and related to the hemoglobin levels in ten heterozygous carriers of beta-thalassemia with different degrees of anemia. Erythrocyte survival values were low, though not related to the degree of anemia, whereas stercobilinogen values and changes in the peripheral blood alpha/beta-chain ratios were so correlated. In the case of bone marrow, on the other hand, the ratio between alpha-chain and beta-chain synthesis was virtually 1, irrespective of the degree of anemia. It is suggested that the severity of anemia in heterozygous carriers is independent of peripheral hemolysis and entirely attributable to destruction of erythroblasts within the marrow.
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Hereditary hemochromatosis (HH) is a genetically heterogeneous disease. The HFE gene resides on chromosome 6 and its mutations account for the majority of HH cases in populations of northern European ancestry. Recently, two new types of hemochromatosis have been identified: Juvenile hemochromatosis (JH or HFE2), which maps to chromosome 1q21, and an adult form defined as HFE 3, which results from mutations of the TFR 2 gene, located at 7q22. We have performed a linkage study in five unrelated families of Greek origin with non-HFE hemochromatosis. Linkage at the chromosome 1q21 JH locus was detected in affected members with the use of polymorphic markers. Comparison of haplotypes between Greek and Italian JH patients revealed the presence of a common haplotype. However, the fact that many other haplotypes carrying the JH defect were observed in the two populations indicates that the respective mutations may have occurred in different genetic backgrounds. We suggest that hemochromatosis patients without HFE mutations should be evaluated for other possible types of hemochromatosis since hemochromatosis type 3 (HFE3) has a clinical appearance similar to HFE 1, and JH may have a late onset in some cases.
Hemojuvelin (HJV) is a recently discovered gene responsible for 1q-linked juvenile hemochromatosis. The majority of mutations characterized in this gene are rare and private, except G320V, identified in patients from different countries. Here, we report the clinical features and the molecular study of a young Irish patient presenting with severe cardiac disease related to iron overload. We sequenced the coding region and the exon-intron boundaries of genes associated with juvenile hemochromatosis, HAMP and HJV encoding hepcidin and hemojuvelin respectively. Two heterozygous HJV mutations were identified: the G320V mutation and the new Q116X mutation that cause a premature stop codon in the protein. This finding increases the number of mutations identified in HJV gene and underlines that the G320V is a recurrent mutation, even in Northern Europe.
A transcription map was generated of a 1 Mb interval including the HFE gene on 6p22. Thirty-seven unique cDNA fragments were characterised following their retrieval from hybridisation of immobilised YACs to primary pools of cDNAs prepared from RNA of foetal brain, human liver, foetal human liver, placenta, and CaCo2 cell line. All cDNA fragments were positioned on the physical map on the basis of presence in aligned and overlapping YACs and cosmid clones of the region. The isolated cDNAs together with established or published sequence tagged sites (STSs) and markers provided sufficient landmark density to cover approximately 90% of the 1 Mb interval with cosmid clones. The precise localisation of two known genes (NPT1 and RING finger protein) was established. A minimum of 14 additional transcription units has also been integrated. Twenty-eight cDNA fragments showed no similarity with known sequences, but 20 of these detected discrete mRNAs upon northern analysis. Their characterisation is still under investigation. Eleven new polymorphisms were also identified and localised, and the HFE genomic structure was better defined. This integrated transcription map considerably extends a recently published map of the HFE region. It will be useful for the identification of genetic defects mapping to this region and for providing template resources for genomic sequencing.
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.
BACKGROUND: Hb Kempsey (beta 99 Asp----Asn) is a high-oxygen affinity hemoglobin, never before reported in Italy, associated with secondary erythrocytosis. It has been found in the heterozygous state in two subjects from the same family originating from the Verona area in Northern Italy. METHODS: The abnormal hemoglobin was studied both at the protein and at the DNA level. The amino acid substitution was identified by fingerprinting and amino acid analysis. The nucleotide replacement was investigated by means of polymerase chain reaction (PCR) of the beta gene and direct sequencing. Oxygen affinity and other functional parameters were assessed on whole blood and on the separate hemoglobin fractions. RESULTS: These studies allowed us to establish the molecular substitution GAT (Asp)----AAT (Asn) at codon 99. Functional studies revealed a left-shifted and biphasic dissociation curve of the proposita, with a very low p50. The two carriers of this hemoglobinopathy have different degrees of polyglobulia, since iron deficiency in one of them reduces total and abnormal Hb. CONCLUSIONS: The compensatory mechanisms for tissue hypoxia are discussed with the conclusion that erythrocytosis has to be preserved in these patients to maintain adequate tissue oxygenation.
By combining the polymerase chain reaction (PCR) of the gamma globin gene promoters with synthetic oligonucleotide analysis we have diagnosed the -196 C----T and the -117 G----A substitutions in heterozygous carriers of non deletional A gamma HPFH from two unrelated Italian families. The identification of the beta-thalassemic defect in a compound heterozygote for -196 A gamma HPFH/beta thalassemia allows us to discuss the effect of this gamma promoter mutation on the globin chain synthetic pattern, and to make a comparison with the mutation at the -117 position.
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