Biomedical subjects
Publications and source records attributed to C Altay.
We report data on a fetus with hydrops fetalis due to a homozygosity for alpha-thalassemia-1, type -(alpha)-20.5 kb; this is the first reported case in a Turkish family. Characterization of the abnormality was based on data from family studies and from alpha-globin gene mapping of the DNA from the parents.
We have studied a few members of two Turkish families, who had a beta-thalassemia of the intermediate type. An abnormal hemoglobin was found in both families, which when present in association with beta(0)-thalassemia was considered to be the primary cause for the increased severity of the disease. In the first family this variant was Hb Knossos [beta 27(B9)Ala----Ser] which occurred together with the frameshift in codon #8 type of beta(0)-thalassemia. This compound heterozygosity, observed for the first time in the Turkish population was characterized by a considerable increase in Hb F production, mainly of the G gamma type, as expected for a chromosome with haplotype IV. In the second family, the variant was Hb City of Hope [beta 69(E13)Gly----Ser] which was present in combination with an unknown type of beta-thalassemia. The increase in Hb F production in the compound heterozygote was minimal. Reversed phase high performance liquid chromatography and the DNA amplification-synthetic oligonucleotide probe procedure were major tools in identifying the different abnormalities.
Globin gene mapping analyses of DNA from numerous Black babies, and from newborns from Sardinia, Sicily, Turkey, and Spain have identified the following: A high incidence of alpha-thalassemia-2 heterozygotes among Black babies with less than 1% Hb Bart's at birth and a high incidence of alpha-thalassemia-2 among Sardinians, but not among Sicilian, Turkish, and Spanish babies. A relatively high incidence of zeta-thalassemia was present among Black babies only, while triplicated zeta was seen in four of the five populations. Two Black babies were each found to have a different theta 1 deletion; two Sardinian babies had a newly discovered approximately 2.5 kb deletion between zeta and psi zeta; four babies had the rare Bgl II polymorphism between psi zeta and psi alpha; and one Black baby lacked the Eco RI site 3' to zeta. Quantitation of the zeta chain by reversed phase high performance liquid chromatography showed that two-thirds of the babies with four alpha genes (alpha alpha/alpha alpha) had levels between 0.1 and 1.0%, while nearly 90% of the babies with -alpha/alpha alpha had similar levels (averaging 0.2% for alpha alpha/alpha alpha; 0.35% for -alpha/alpha alpha; 0.75% for -alpha/-alpha). Additional data indicated that the occurrence and level of zeta are related to the level of beta, i.e. the gestational age. The presence of a zeta triplication did not affect the level of zeta in cord blood. The extensive search for gamma-globin gene anomalies resulted in the discovery of a chromosome with five gamma genes. gamma-Thalassemia was rare in all populations, while the -G gamma-G gamma- gene arrangement was mainly observed among Black babies; this arrangement is primarily responsible for high G gamma levels in cord blood samples. The strong correlation between the presence or absence of a C----T mutation at position -158 (measured in Xmn I digests) and the level of G gamma was confirmed for adult blood samples. A search for possible anomalies in the -delta-beta- region through gene mapping with Eco RV gave negative results except for the discovery of a polymorphic site 5' to delta in one of the 371 Black babies tested.
The nondeletional types of hereditary persistence of fetal hemoglobin (ndHPFH) concern the continued synthesis of hemoglobin (Hb) F with either G gamma or A gamma chains in amounts varying from 5% to 30%. Several mutations have been identified in either the A gamma or G gamma promoter which are considered causative to the continued production of one of the two gamma chains because the substitutions occur in sequence motifs essential for the expression characteristics of the gamma-globin gene in the 3' position. We report the discovery of a T----C mutation at position -175 in the A gamma promoter which was associated with a greatly increased level of Hb F (with mainly A gamma) and a decreased level of Hb A in the one (Black) heterozygote who had a beta c gene in trans. The same mutation has been observed in the G gamma promoter of a Black heterozygote who had high levels of Hb F with G gamma chains only. A detailed comparison between these two individuals indicated significant differences in the levels of Hb F and Hb A which may result from an additional mutation at position -158 in the G gamma promoter.
Sequence analyses of amplified DNA from a Yugoslavian patient with Hb Lepore-beta-thalassemia and from his father with a simple beta-thalassemia trait have revealed a T----A mutation within the ATA box at a position 30 base pairs upstream from the Cap site. The nucleotide substitution was confirmed through dot-blot analysis of amplified DNA with specific 32P-labeled synthetic oligonucleotide probes. The patient had a clinically severe condition; his Hb Lepore-beta-thalassemia was of the beta + type, as about 8-10% of the non-alpha chain was normal beta A. The same T----A mutation at nucleotide -30 was present on both chromosomes of a young Turkish patient who suffered from a thalassemia intermedia with a low level of Hb F (13.1%) and a relatively high beta A chain synthesis. These data are similar to those obtained for other types of beta +-thalassemia caused by comparable substitutions at positions 31, 29, and 28 base pairs upstream from the Cap site of the beta-globin gene.
Two hundred fourteen children with acute nonlymphoblastic leukemia (ANLL) were diagnosed between July 1975 to January 1987 in our center. Only 106 (50%) of the children could be treated. An initial hematologic remission was attained in 61 (58%) with a median duration of hematologic remission of 7.5 months and median survival of 12 months. Five patients who completed 36 months of therapy are still in initial remission, less than or equal to 84 months. Exophthalmos at presentation, which is clearly related to shorter duration of remission, was observed in 11% of these children. In two cases, it was the first sign of leukemia, 6 and 7 months prior to obvious bone marrow involvement. Twenty percent of the 61 patients who achieved remission discontinued their chemotherapy during the course of treatment while they were in remission, which indicates a different problem in the treatment of these patients in Turkey. Despite administration of similar treatment protocols, the prognosis of our patients was worse than the results observed in developed countries. We conclude that poor socioeconomic and nutritional conditions should also be considered among the high-risk factors for children with ANLL, as experienced in our patients with acute lymphoblastic leukemia (ALL).
Lactate, pyruvate, and alanine levels were investigated in patients with iron deficiency anemia and other types of anemia. The study was carried out on 36 children between 2 and 16 years of age. The study group was divided into three groups, each comprised of 12 children. It was shown that the anemic children have lower PO2, higher PCO2 and higher levels of lactate, pyruvate, and alanine than the control group (p less than 0.05). There was a negative linear correlation between lactate levels and hemoglobin values (r = -0.6213; p less than 0.05), but no correlation between hemoglobin and the alanine and pyruvate levels. Levels of lactate, pyruvate and alanine were similar in the iron deficiency and the other anemia groups. In conclusion, iron has no direct effect on the levels of lactate, pyruvate, and alanine, but the hypoxemia caused by anemia could be responsible for the higher levels of the lactate, pyruvate, and alanine. In cases with high levels of lactate, pyruvate, and alanine, anemia has to be considered in the differential diagnosis of hyperlactatemia.
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Through the procedure of gene amplification combined with hybridization to synthetic 19 base pair (bp) oligonucleotide probes, it has been possible to identify nine different mutations in the DNA of 47 subjects from Turkey and Northern Cyprus with a beta-thalassemia homozygosity. The IVS-I nucleotide (nt) 110 G----A and the IVS-I nt 6 T----C substitutions and the frameshift at codon 8 were most frequently observed. Direct correlations were made between these data and clinical observations; mild disease was associated with homozygosity for IVS-I nt 6 T----C, for frameshift at codon 8, for the C----G substitution at nt -87, and for IVS-I nt 5 G----T, and for a double heterozygosity for some of these conditions. Moderate disease, observed in some of the patients, could be explained by combinations of specific mutations. All mutations were associated with specific haplotypes, while in some the observed beta zero-thalassemia was of the mild type due to a considerable production of Hb F.
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Almost 10 years ago we reported in this journal the characterization of Hb Hacettepe or alpha 2 beta (2)127(H5)Gln----Glu. Unfortunately, we have to conclude that the original characterization of this Turkish variant was in error. The corrected data are presented in this short communication. The variant (alpha 2 beta (2)65(E9)Lys----Met) was (re)named Hb J-Antakya, after the city where the family resides. An abnormal Hb, observed in a Spanish family and named Hb Complutense, had the beta 127 Gln----Glu substitution, erroneously assigned to the Turkish variant.
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We have studied the hematology, hemoglobin composition, and globin gene arrangements in one young Turkish boy with a beta zero-thalassemia homozygosity and in 11 of his relatives. Evidence is presented that the chromosome with the beta zero-thalassemia determinant carries a gamma-globin gene quadruplication, perhaps in a -G gamma-G gamma-G gamma-A gamma-gene arrangement. The eight gamma-globin genes in this patient produced G gamma and A gamma chains in a 95 to 5 ratio, and nearly 99% of the patient's hemoglobin was of the fetal type. The clinical condition resembled that of a thalassemia intermedia. HbF levels in eight beta-thalassemia heterozygotes varied between 0.5 and 4.2% and the percentages of G gamma in this HbF averaged at 87% or 95%; this level is to some extent related to the haplotype of the normal chromosome. All subjects carried four alpha-globin genes; a new BglII polymorphism was observed within the psi alpha-globin gene.
A 10-year-old classic hemophiliac and 1.5-year-old child with hemophilia B who developed acute lymphocytic and acute myelomonocytic leukemia respectively are presented. No changes in coagulation status of the patients were observed. It is suggested that hemophiliacs should be regarded as "population at risk" for the development of leukemia.
Family studies were performed in 10 patients from seven different families with homozygous beta zero thalassaemia intermedia and in three patients with homozygous beta+ or compound heterozygous beta+ and beta zero thalassaemia intermedia. In nine of the 10 families at least one of the parents was found to have raised Hb A2 and Hb F. In the heterozygotes with increased Hb A2 and Hb F, the means of Hb F and MCV were significantly higher than those observed in regular Hb A2 thalassaemia heterozygotes. However, the severity of imbalance in in vitro haemoglobin synthesis was similar in these two groups. The imbalance in the alpha/non-alpha synthetic ratio was heterogeneous in the patients, being 2.1 and 4.0. Segregation of the raised Hb F from the Hb A2 beta thalassaemia determinant was found to be possible in only one of the 36 heterozygotes. This may exclude the possibility of the presence of an additional determinant responsible for the activation of the gamma chain. The G gamma/A gamma ratio of Hb F was that of the fetal type (G gamma was between 50 and 71% of the total gamma chain). The A gamma T variant of gamma chain was not detected in cis of the beta zero thalassaemia determinant characterised by increased Hb F and Hb A2. A retrospective study of 180 patients with beta thalassaemia and their parents indicated that the combined rise in Hb A2 and Hb F was more common in the heterozygous parents (11 out of 30 parents) of the patients with beta zero thalassaemia than it was in the parents of patients with beta+ thalassaemia (three out of 140 parents). The presence of increased Hb A2 and Hb F in the heterozygote may in some cases determine the relative mildness of the disease.
A total of 15 patients from different families with thalassaemia intermedia was studied. Haematological studies showed that the fetal haemoglobin was only slightly raised, being between 2 and 11.5% of the total haemoglobin. Haemoglobin A2 was high in all cases. The family study indicated that homozygosity or compound heterozygosity for beta thalassaemia was present in five patients, while dominant inheritance was observed in three. In seven patients family studies were not sufficient to predict the genotype. Haematological findings in the parents of the homozygous patients were as severe as those seen in common Hb A2 beta thalassaemia traits. The decrease in MCH and MCV was more severe and the Hb A2 higher in homozygous patients than in cases of common beta thalassaemia major (p less than 0.01, p less than 0.01, and p less than 0.001 respectively). The imbalance in in vitro globin synthesis was more severe in classical beta thalassaemia major than in homozygous patients in this study (p less than 0.01). However, the imbalance in alpha/non-alpha synthetic ratios showed variation among the homozygous and heterozygous patients in this study (2.1 to 4.0). Haematological severity and Hb F value showed some slight variation among affected persons of the same family in the case of patients with severe beta thalassaemia heterozygosity. The G gamma/A gamma ratio of haemoglobin F was found to be close to that of the adult level. Haematological studies suggested that clinical and haematological findings were more severe in patients with homozygous beta thalassaemia than in patients with heterozygosity for beta thalassaemia. The prevalence of thalassaemia intermedia with low Hb F and increased Hb A2 was found to account for 3% of the Turkish beta thalassaemic patients diagnosed before the age of 8 years.
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We describe two novel arrangements of the human fetal globin gene region: one chromosome with two linked A gamma genes (A gamma-A gamma) and two chromosomes with two linked G gamma genes (G gamma-G gamma). The gamma genes of these three chromosomes were cloned and the unusual 5' A gamma gene and one of the unusual 3' G gamma genes were partially sequenced. Both of these unusual genes differ from the genes normally found at their respective locations by a nucleotide substitution at the site of the single coding region difference between normal G gamma and A gamma genes. In both cases, the substitution is identical to the nucleotide found at that position in the normal neighboring gene. The unusual 3' G gamma gene also differs from normal A gamma genes at two other nucleotide positions, but both differences appear to be "private" or exclusive to this particular gene. These unusual fetal globin gene arrangements could have arisen from point mutations or from gene conversions of limited extent, the boundaries of which have been determined for all three chromosomes.