C. Altay

β-Thalassemia in Turkey

A review is presented of the various β-thalassemia alleles observed in nearly 191 patients with β-thalassemia major and their 182 heterozygous relatives. Determination was by gene amplification and dot-blot hybridization with synthetic probes, specific for 27 different mutations. Eighteen mutations have been observed; six of these acount for nearly 83% of all thalassemia abnormalities (Table I). A new mutation, i.e. a G ↣ C mutation at the acceptor splice site of IVS-I, was found in one teenager who was homozygous for this disease. the high consanguinity among the families was considered the main reason for the high number of patients with a homozygosity for the IVS-I-110 (G ↣ A) mutation. Combinations of different mutations were present in many patients; some were mildly affected because of the specific mutation present on one chromosome. Combinations of classical β-thalassemia and an abnormal hemoglobin mainly concerned Hb S. Hbs Knossos and Lepore were rare occurrences. A comparison of hematological da...

βs haplotypes in various world populations

SummaryWe have determined the βs haplotypes in 709 patients with sickle cell anemia, 30 with SC disease, 91 with S-β-thalassemia, and in 322 Hb S heterozygotes from different countries. The methodology concerned the detection of mutations in the promoter sequences of the Gγ- and Aγ-globin genes through dot blot analysis of amplified DNA with 32P-labeled probes, and an analysis of isolated Hb F by reversed phase high performance liquid chromatography to detect the presence of the AγT chain [Aγ75 (E19) Ile→Thr] that is characteristic for haplotype 17 (Cameroon). The results support previously published data obtained with conventional methodology that indicates that the βs gene arose separately in different locations. The present methodology has the advantage of being relatively inexpensive and fast, allowing the collection of a vast body of data in a short period of time. It also offers the opportunity of identifying unusual βs haplotypes that may be associated with a milder expression of the disease. The numerous blood samples obtained from many SS patients living in different countries made it possible to compare their hematological data. Such information is included (as average values) for 395 SS patients with haplotype 19/19, for 2 with haplotype 17/17, for 50 with haplotype 20/20, for 2 with haplotype 3/3, and for 37 with haplotype 31/31. Some information on haplotype characteristics of normal βA chromosomes is also presented.

The Fanconi Anemia Group E Gene, FANCE, Maps to Chromosome 6p

Fanconi anemia (FA) is a genetically heterogeneous autosomal recessive disease with bone marrow failure and predisposition to cancer as major features, often accompanied by developmental anomalies. The cells of patients with FA are hypersensitive to DNA cross-linking agents in terms of cell survival and chromosomal breakage. Of the eight complementation groups (FA-A to FA-H) distinguished thus far by cell fusion studies, the genes for three-FANCA, FANCC, and FANCG-have been identified, and the FANCD gene has been localized to chromosome 3p22-26. We report here the use of homozygosity mapping and genetic linkage analysis to map a fifth distinct genetic locus for FA. DNA from three families was assigned to group FA-E by cell fusion and complementation analysis and was then used to localize the FANCE gene to chromosome 6p21-22 in an 18.2-cM region flanked by markers D6S422 and D6S1610. This study shows that data from even a small number of families can be successfully used to map a gene for a genetically heterogeneous disorder.

The G→A Mutation at Position +22 31 to the Cap Site of the β-Globin Gene as a Possible Cause for a β-Thalassemia

We describe the occurrence of a chromosome with a G→A mutation at position +22 relative to the Cap site that was found in five patients with β-thalassemia. All patients had a common type of β-thalassemia mutation on the second chromosome, namely the frameshift at codon 8 (-AA), the IVS-I-110 (G→A) and the IVS-II-1 (G→A) mutations. The β genes of two patients, including the 5′ and 3′ untranslated regions, were completely sequenced and no other mutations, except a few polymorphic sites, were observed. Dot-blot analyses failed to demonstrate this G→A mutation at +22 in nearly 400 β-thalassemia chromosomes and 180 normal chromosomes. Hetero-zygotes have the features of a high Hb A2-β-thalassemia hetero-zygosity, although the hematological parameters might be less abnormal than observed in heterozygotes for the more common β-thalassemia mutations. The possibility has been presented suggesting that this mutation might impair the binding of mRNA to ribosomes. Another mutation in this segment of DNA, i.e. a C→G m...

A Search for Anomalies in the ζ,α,β, and γ Globin Gene Arrangements in Normal Black, Italian, Turkish, and Spanish Newborns

Globin gene mapping analyses of DNA from numerous Black babies, and from newborns from Sardinia, Sicily, Turkey, and Spain have identified the followingA high incidence of α-thalassemia-2 heterozygotes among Black babies with less than 1% Hb Barts at birth and a high incidence of α-thalassemia-2 among Sardinians, but not among Sicilian, Turkish, and Spanish babies. A relatively high incidence of ζ-thalassemia was present among Black babies only, while triplicated ζ was seen in four of the five populations. Two Black babies were each found to have a different θl deletion; two Sardinian babies had a newly discovered β 2.5 kb deletion between ζ and ψζ; four babies had the rare Bgl II polymorphism between ψζ and ψα; and one Black baby lacked the Eco RI site 3’ to ζ Quantitation of the ζ chain by reversed phase high performance liquid chromatography showed that two-thirds of the babies with four α genes (αα/αα) had levels between 0.1 and 1.0%, while nearly 90% of the babies with -α/αα had similar levels (aver...

Myeloperoxidase Activity and Bactericidal Function of PMN in Iron Deficiency

In children with iron deficiency anemia, bactericidal capacity of polymorphonuclear leukocytes (PMN) and serum opsonic activity were studied. Nitroblue tetrazolium test (NBT), hexose monophosphate (HMP) shunt activation, and myeloperoxidase (MPO) activity of PMN of these cases were also examined. Bactericidal capacity and HMP shunt activation were found to be decreased in iron deficiency anemia ( p less than 0.001). MPO activity, NBT test, and serum opsonic activity were found to be within normal limits. After 1 1/2 months of iron therapy there was an improvement in bactericidal capacity and it returned to a normal level after 3 months of therapy.

The levels of ζ, γ, and δ chains in patients with Hb H disease

SummaryDetails are given of a study of blood samples from 24 patients with Hb H disease from different Mediterranean countries and from the Far East. Four different types of α-thal-1 (--) were observed, namely-(α) (∼ 20.5-kb deletion);--MED-I (∼ 17.5-kb deletion);--MED-II (>26.5-kb deletion); and--SEA (∼ 18-kb deletion, in Orientals only). The α-thal-2 was mainly of the deletion type (16 with the 3.7-kb deletion; 1 with the 4.2-kb deletion), while 4 of the 7 patients with a nondeletional type had the five-nucleotide deletion at the donor splice site of the first intron of the α2 gene. All patients had a mild-to-moderate hemolytic anemia; no significant differences in hematology were observed between the groups. Hb A2 was decreased to about one-third of the normal level. The Hb H formation varied considerably and its quantitation was not always satisfactory. Patients with Hb H disease due to any α-thal-1 combined with a nondeletional α-thal-2 had the highest Hb H levels and a more marked anemia. The ζ chain production was small and absent in patients with the MED-II type of α-thal-1 because this deletion included the ζ and ψζ genes. The highest ζ chain levels were present in the four patients with the SEA type of α-thal-1. The γ chain production was increased, particularly in patients with a mutation of C → T at position-158 to the Gγ globin gene. This γ chain was primarily present as Hb Barts (or γ4) and only about 15% was recovered as Hb F or α2γ2. The evaluation of the rate of γ chains produced in these patients was greatly facilitated by data from one patient who had Hb H disease and a heterozygosity for the Aγ-β+. The low levels of Hb A2 and of Hb F (relative to Hb Barts) can be explained by a decreased affinity of α chains for δ and γ chains as compared with β chains in conditions of severe α chain deficiency.

Evidence for the Existence of the PAF Acetylhydrolase Mutation (Val279Phe) in Non-Japanese Populations: A Preliminary Study in Turkey, Azerbaijan, and Kyrgyzstan

Deficiency of plasma platelet-activating factor (PAF) acetylhydrolase resulting from a missense mutation (Val279Phe) in exon 9 of the gene has been described exclusively in the Japanese population with a very high frequency. This study describes the distribution of the mutation in Turkey and two other Turkic nations, Kyrgyzstan in central Asia and Azerbaijan bordering the Caspian Sea. Among 358 unrelated healthy subjects studied from Turkish population, only 3 had the mutation in heterozygous state (0.84%). Family studies also revealed the presence of homozygous individuals in close relatives of one of these subjects. Among 143 healthy subjects studied from Kyrgyzstan, 12 were heterozygous for the mutation (8.4%). No mutation was detected among 100 healthy individuals studied from Azerbaijan. However, it was suggested that the number of subjects was not enough to draw any conclusion about the prevalence of the mutation in the populations studied. Contrary to the previous notions, identification of the mutation in Turkey and Kyrgyzstan shows the existence of the mutation in non-Japanese populations as well.

Hb H disease caused by a homozygosity for the AATAAA→AATAAG mutation in the polyadenylation site of the α2-globin gene : hematological observations

We have identified 7 patients with Hb H disease as homozygotes for a mutation in the polyadenylation site (AATAAA-->AATAAG) and have compared their hematological data with those of Hb H patients having other types of alpha-thalassemia determinants. All 7 patients exhibited moderate anemia with microcytosis and hypochromia being similar to that observed in the other patients. Relatives with a heterozygosity for this mutation are borderline microcytic and hypochromic without a significant anemia but with a low in vitro alpha/beta chain synthesis ratio. Analyses of the hemoglobin components identified low levels of Hb A2 and Hb H that were comparable to those found in other patients with Hb H disease; the level of the zeta-chain was low (average 0.14%).

Possible factors influencing the haemoglobin and fetal haemoglobin levels in patients with β‐thalassaemia due to a homozygosity for the IVS‐I‐6 (T→C) mutation

Summary. We have collected haematological, haemoglobin (Hb) and DNA sequence data for 29 patients with a homozygosity for the IVS‐I‐6 (TC) mutation with the intention of identifying factors contributing to the observed variability in the severity of the disease. None of the patients had received blood transfusion therapy for at least 6 months prior to the study. Hb levels varied from 5·0 to 9·9 g/dl. Patients with high Hb F (more than 1·5 g/dl or <20%) had high total Hb levels (7·5–9·7 g/dl) but some with low Hb F also had high total Hb levels; two had a concomitant α‐thalassaemia‐2 (α‐thal‐2) heterozygosity. An inverse correlation between the Hb F and Hb A2 levels was observed. The majority of the patients were homozygous for haplotype VI (49/58 chromosomes) but haplotypes IV (2/58) and VII (7/58) were also present. The only haplotype IV homozygote had high Hb F levels with high Gγ values and the CT mutation at position – 158 in the Gγ promoter, while both high and low Hb F levels were observed among patients with haplotypes VI and VII. Analysis of sequence variations in regulatory regions included the 5 hypersensitive sites (HS) 4, 3 and 2 of the locus control region (LCR), the Gγ and Aγ 5 flanking regions, the second intervening sequence (IVS‐II), and the 5 β‐globin gene region in two patients with high Hb F (one homozygote each for haplotypes VI and IV), and in two patients with low Hb F levels (one homozygote each for haplotypes VI and VII). Haplotype specific differences were observed in the LCR 5 HS‐2 and in the Gγ and Aγ flanking and IVS‐II regions; however, no differences were present between the low and high Hb F‐producing haplotype VI chromosomes, suggesting a major role for factors which are not linked to the β‐globin gene cluster in mediating γ‐globin gene expression in patients with this type of β‐thal.