1/9. Molecular basis of Sp alpha I/65 hereditary elliptocytosis in North africa: insertion of a TTG triplet between codons 147 and 149 in the alpha-spectrin gene from five unrelated families.Hereditary elliptocytosis in North africa is frequently associated with the alpha I/65 spectrin variant, characterized by an abnormal alpha I 65-kD instead of the normal alpha I 80-kD peptide following limited trypsin digestion of whole spectrin. A similar variant (although it yielded a 68-kD fragment) has been shown recently, in two black patients, to result from the insertion of a leucyl residue at position 148 (Marchesi et al: J Clin Invest 80:191, 1987). In order to determine if the underlying molecular defect was the same in North Africans and blacks (who originate from both sides of the Sahara Desert), we performed analysis directly at the dna level. Starting from the dna of an Algerian alpha I/65 heterozygote in whom the mutation was associated with identifiable RFLPs, we cloned and sequenced the alpha-spectrin gene region, which includes the mutation. We thus identified an extra leucine codon (TTG) between codons 147 and 149, the coding sequence becoming CAG TTG TTG CTG instead of CAG TTG CTG. We then used the polymerase chain reaction (PCR) method and dot-blot hybridization of the amplified dna with mutant and normal allele-specific oligonucleotides to screen the dna from four other unrelated North African subjects with Sp alpha I/65 hereditary elliptocytosis. In all families we studied, these subjects were heterozygous for the TTG insertion. These results demonstrate that Sp alpha I/65 hereditary elliptocytosis has the same molecular basis in North Africans and blacks.- - - - - - - - - - ranking = 1keywords = black (Clic here for more details about this article) |
2/9. Clinical and laboratory study of two Caucasian families with hereditary pyropoikilocytosis and hereditary elliptocytosis.Hereditary pyropoikilocytosis (HPP) is a severe, congenital hemolytic anemia occurring almost exclusively in black persons and characterized by extreme red blood cell anisopoikilocytosis. The authors report two unrelated white females with HPP. Both had severe hemolytic anemia at birth, red blood cell morphologic features characteristic for HPP, and increased thermal sensitivity of the red blood cells. Examination of the red blood cell membranes of both patients showed markedly unstable membrane skeletons when subjected to shear stress, spectrin dimer association defects with increased dimers, and partial spectrin deficiency. Limited tryptic digestion of the spectrin molecule from both patients yielded an abnormal pattern with a decrease in the normal 80,000-dalton alpha I domain and a concomitant increase of an abnormal 74,000-dalton peptide (Sp alpha 1/74). One parent and one sibling of one of the patients with HPP had hereditary elliptocytosis (HE) and the Sp alpha 1/74 defect. The other patient with HPP was different from others reported in that both parents were hematologically and biochemically normal. In addition, her daughter had HE and the Sp alpha 1/74 defect.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |
3/9. Double inheritance of an alpha I/65 spectrin variant in a child with homozygous elliptocytosis.Hemolytic anemia with red cell fragmentation, poikilocytosis, and elliptocytosis was discovered in a 6-week-old black infant. Both parents and a brother of the propositus had compensated mild Hereditary Elliptocytosis (HE). Elliptocytosis was prominent in the proband's father with the presence of numerous rod-shaped cells whereas, in the proband's mother, elliptocytosis was less marked and cells were less elongated than in the father. The proband's red cells fragmented at 45 degrees C instead of 49 degrees C for control cells. Both the parents' and brother's red cells fragmented at 47 degrees C. The deformability of the proband's red cells was markedly reduced when measured with the ektacytometer; the red cells of both the proband's parent and brother exhibited an intermediate decrease in red cell deformability. spectrin self-association was defective in the propositus as well as in his parents and brother. Limited tryptic digestion of the proband's spectrin, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), revealed a complete absence of the normal 80,000 dalton alpha I domain and the presence of an abnormal 65,000 dalton peptide. Two-dimensional isoelectric focusing/SDS-PAGE of limited tryptic digests of spectrin from both the proband's parents and brother revealed a decrease in the normal 80,000 alpha I domain and the presence of the 65,000 peptide variant. On the basis of biochemic studies performed on the patients' spectrin, we concluded that the proband had homozygous HE, having inherited the structural defect of spectrin present in a heterozygous state in each of his parents. On a clinical and morphologic level, homozygous HE imitates two other forms of congenital hemolytic anemia associated with a spectrin self-association defect: HE with pycnocytosis in infancy and Hereditary Pyropoikilocytosis. This report emphasizes the importance of confronting clinical and rheological as well as biochemical investigations in studying and discussing different entities.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |
4/9. A new abnormal variant of spectrin in black patients with hereditary elliptocytosis.Seven black patients with mild hereditary elliptocytosis (HE) from five unrelated families were studied. The erythrocytes of these patients exhibited an abnormal thermal sensitivity (between 45 degrees C and 47 degrees C instead of 49 degrees C). An important defect of spectrin dimer self-association was detected in two ways: (1) the proportions of spectrin dimer (SpD) extracted from membranes at 4 degrees C under low ionic strength conditions were increased between 25% and 56% (normal value 15% /- 2%); (2) the spectrin dimer tetramer conversion in solution were defective with an association constant value between 0.4 and 2.4 X 10(5) M-1 for a normal value of 6 /- 0.4 X 10(5) M-1. spectrin (Sp) from HE patients and normal volunteers (32 black and 22 white subjects) was submitted to limited tryptic digestion, followed by one- or two-dimensional separation of the peptides. Peptide patterns of crude Sp from all seven HE patients exhibited a marked and reproducible decrease in 80,000-dalton peptide (previously identified as the dimer-dimer interaction domain of the alpha-chain) and a concomitant appearance of a novel 65,000-dalton peptide. A minor fragment at 28,000 daltons was also decreased. Tryptic digestion of HE spectrin dimer and tetramer (SpT), isolated after the SpD self-association procedure in solution, revealed modifications (decrease in the 80,000-dalton peptide and presence of a 65,000-dalton peptide) predominantly in HE SpD when peptide patterns of HE SpT were quite similar to control SpT patterns. Immunoblots with anti-alpha-chain antibodies revealed that the 65,000-dalton peptide derived from the alpha-chain. Kinetic studies of Sp digestion showed that the 65,000-dalton peptide did not result from further digestion of a 74,000 intermediate and was not a precursor of 46,000- to 50,000-dalton peptides. These results show a new structural defect of Sp-alpha-chain, associated with a defective Sp dimer self-association in HE.- - - - - - - - - - ranking = 2keywords = black (Clic here for more details about this article) |
5/9. Sp alpha I/65: a new variant of the alpha subunit of spectrin in hereditary elliptocytosis.Two molecular defects involving the spectrin heterodimer (SpD) contact site of the alpha chain (the alpha I domain) were previously identified using limited tryptic digestion followed by two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both are characterized by atypical peptide maps which reveal a marked decrease of the 80,000-dalton alpha I domain and a formation of new major peptides of either 74,000 (Sp alpha I/74) or 46,000 (Sp alpha I/46) daltons. We now report a third variant of the spectrin alpha chain, designated Sp alpha I/65, in three unrelated black families. In all three probands, the percentage of SpD in the low ionic strength (O degrees C) membrane extracts was increased to 19% to 32%. One- and two-dimensional electrophoretic separations of limited tryptic digests of spectrin from all three probands revealed a decrease of the alpha I domain of spectrin and the concomitant appearance of peptides at 65,000 daltons and isoelectric points ranging from 5.2 to 5.3. The abnormal 65,000-dalton peptides could be stained with an antiserum which had been raised against the alpha I domain, indicating that it was derived from the alpha I domain.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |
6/9. Hereditary pyropoikilocytosis: report of two cases from saudi arabia.Hereditary pyropoikilocytosis is a rare type of congenital hemolytic anemia reported only in American black children. We report the first two occurrences in Saudi children. This is an autosomal-recessive trait as proved by normal parents and two affected children. A pathogenetic and probably causal relationship with apparent elliptocytosis seems clear as three sibs have that condition.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |
7/9. Hereditary elliptocytosis: morphologic abnormalities during acute hepatitis.A 10-year-old black girl with hereditary elliptocytosis had a transient increase in hemolysis and unusual red cell morphologic changes during an episode of acute hepatitis. Changes in membrane lipids of these elliptocytes with defective membrane skeletal protein and abnormal distribution of cholesterol may be responsible for this phenomenon.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |
8/9. The pyropoikilocytosis-elliptocytosis syndrome in a black South African infant: clinical and hematological features.A black infant presented in the newborn period with severe red cell fragmentation, pyknocytosis, and hemolysis necessitating repeated exchange transfusions. Exposure of the red cells to 45 degrees C in vitro caused membrane budding, fragmentation, and sphering similar to that described in pyropoikilocytosis. By 12 months of age the clinical and hematologic picture had evolved to one of a compensated hemolytic disorder with elliptocytosis, but the degree of abnormal thermal sensitivity remained unchanged. osmotic fragility and authohemolysis tests gave results intermediate between hereditary elliptocytosis and hereditary pyropoikilocytosis. It appears that there is considerable heterogeneity within the red cell membrane disorders exhibiting altered thermal sensitivity.- - - - - - - - - - ranking = 1.6666666666667keywords = black (Clic here for more details about this article) |
9/9. Expression of spectrin alphaI/50 hereditary elliptocytosis and its association with the alphaLELY allele.Hereditary elliptocytosis (HE) is a group of hemolytic anemias characterized by the presence of elliptical erythrocytes. The underlying alterations lie in the proteins of the membrane skeleton. Defects of the alphaI domain of spectrin have been defined based on a decrease in the normal 80-kD alphaI domain and a concomitant increase in one or more lower molecular weight peptides. We have studied three Brazilian kindreds with black ancestry, who presented mild common spalphaI/50 HE. Our aim was to determine the molecular alteration responsible for the spalphaI/50 HE observed in these three kindreds and to evaluate the presence and influence of allele alphaLELY in the expression of this type of HE. In order to establish the molecular defect, exons 5, 6 and 11 were amplified and submitted to a nonradioactive single strand conformation polymorphism protocol. An identical band shift in exon 6 was observed in all 3 patients and their affected relatives. Direct sequencing of the amplification products of exon 6 showed the same molecular defect in all patients: a T-->C substitution, responsible for the L260P mutation. Allele alphaLELY, detected by PCR and restriction enzyme digestion, was present in the heterozygous form in the three propositi and was associated in trans with the elliptocytogenic mutation. Blood smears of the patients with HE and alphaLELY in trans showed pronounced elliptocytosis, poikilocytosis and a few small red cell fragments, whereas the blood smears of their relatives, who had HE without allele alphaLELY, showed mild common HE with a predominance of ovalocytes and the absence of poikilocytes. We conclude that allele alphaLELY does not lead to the worsening of clinical conditions when associated in trans with mild HE, but can be easily distinguished by a blood smear analysis. The predominance of the L260P mutation in the kindreds studied could be related to the colonization of brazil during the slave trade by Africans from the benin-togo area, where this mutation is particularly common.- - - - - - - - - - ranking = 0.33333333333333keywords = black (Clic here for more details about this article) |