C. Kattamis

The triplicated α‐globin gene locus in β‐thalassaemia heterozygotes: clinical, haematological, biosynthetic and molecular studies

Excess α‐globin chains play a major role in the pathophysiology of homozygous β‐thalassaemia. In β‐thalassaemia carriers a minor effect of α‐globin chain excess is reflected in a minimal or mild anaemia without clinical symptoms. Factors that increase α‐chain excess in heterozygotes are expected to accentuate the severity of the clinical and haematological phenotype.

CORRELATION OF CLINICAL PHENOTYPE TO GENOTYPE IN HAEMOGLOBIN H DISEASE

Clinical assessment, haematological studies, and globin gene mapping were performed in 21 Greek subjects with haemoglobin H disease. Clinical phenotypes ranged from mild, and virtually asymptomatic, to severe cases requiring transfusion. The severe clinical phenotype was exclusively associated with non-deletion genotypes, whereas the mild and intermediate phenotypes occurred with deletion genotypes. Patients with non-deletion genotypes had higher levels of Hb H. For deletion genotypes of haemoglobin H disease, the value of antenatal diagnosis is questionable. In non-deletion genotypes, antenatal diagnosis should be considered, because of the more severe clinical course observed in these patients.

Characterization of more than 85% of cystic fibrosis alleles in the Greek population, including five novel mutations

Abstract To completely characterize the spectrum of mutations in the cystic fibrosis transmembrane conductance regulator gene in Greek cystic fibrosis (CF) patients, we screened 500 CF chromosomes by denaturing gradient gel electrophoresis followed by direct sequencing. We identified 48 mutations, accounting for 85.6% of CF chromosomes. They included eight novel mutations, three of which we have described before and five (E822X, Y247X, 2752–26A→G, 3152delT, and 2751+T→A), which are described in this report. The detection of such a high proportion of Greek CF mutations is important for improving prenatal and genetic diagnosis of CF in Greece.

A base substitution (T→C) in codon 29 of the α2-globin gene causes α thalassaemia

Summary. We have identified three individuals of Greek or Greek Cypriot origin with an atypical form of HbH disease characterized by a severe hypochromic microcytic anaemia associated with relatively small amounts of HbH in the peripheral blood. Molecular analysis has shown that each is a compound heterozygote for a previously described mutation affecting the poly A addition signal (AATAAA→ÁTAAG) and a previously undescribed mutation involving a T→C transition in codon 29 of the α2 gene causing a leucine→pro‐line substitution. Although this mutation would be expected to produce an unstable haemoglobin and hence a haemolytic anaemia, simple heterozygotes for the α29Leu→Pro mutation have the phenotype of α‐thalassaemia trait.

Molecular, haematological and clinical studies of the −101 C → T substitution of the β‐globin gene promoter in 25 β‐thalassaemia intermedia patients and 45 heterozygotes

We report the clinical, haematological, biosynthetic and molecular data of 25 double heterozygote β‐thalassaemia intermedia patients and 45 β‐thalassaemia heterozygotes with the C → T substitution at nucleotide position −101 from the Cap site, in the distal CACCC box of the β‐globin gene promoter. This mutation is considered the most common amongst the silent β‐thalassaemia mutations in Mediterranean populations. Of the 25 compound heterozygotes for the β−101 C → T and common severe β‐thalassaemia mutations, all but one had mild thalassaemia intermedia preserving haemoglobin levels around 9.5 g/dl and haemoglobin F levels < 25%. The only transfused patient was characterized to have an additional α‐globin gene.

Characterization of Three Types of β0-Thaussemia Resulting from a Partial Deletion of the β-Globin Gene

Three patients heterozygous for a partial deletion of the β-globin gene were studied: an American Black with an ≈1.35 kb deletion, a Turkish patient with an ≈300 nucleotide deletion, and a Greek patient with a newly discovered deletion of 44 nucleotides. The DNA was amplified by the polymerase chain reaction procedure and sequenced; only the DNA with the deletion was amplified for the patients with the ≈1.35 kb and ≈300 bp deletion, facilitating the interpretation of the sequencing gels. The amplified DNA fragments from these two chromosomes were also cloned into a plasmid vector and sequenced. The size of the deletion found in the Turkish patient is 290 nucleotides and includes 123, 124 or 125 nucleotides 5′ to the Cap site, the 5′ untranslated region, exon 1, and 25, 24, or 23 nucleotides of the first intron. The total size of the deletion of the Black patient is 1393 nucleotides including 485 (484) bp 5′ to the Cap site, exon 1, intron 1, exon 2, and 413 (414) nucleotides of the second intron. The new ...

Uncommon manifestations of histiocytosis X

Histiocytosis X is a group of disorders of uncertain etiology with a variety of manifestations that are usually related to the age of the patient. Treatment consists of local curettage, irradiation and chemotherapy. The prognosis depends on the systems involved. The oral and perioral tissues are occasionally involved and often lead to the diagnosis. We report a case with spinal cord involvement and a case of facial nerve paralysis secondary to involvement of the petrosal bone. Also included is a case of involvement of the mandibular condyle.

Occurrence of Gγ Hb F in Greek HPFH: Analysis of Heterozygotes and Compound Heterozygotes with β Thalassaemia

Summary. Haemoglobin F has been isolated from the red cells of individuals with the Greek form of hereditary persistence of fetal haemoglobin (HPFH), and the glycine/alanine composition of the γCB3 peptides determined. In contrast to previous reports we have shown that the Hb F of the Greek HPFH heterozygotes contains significant amounts of Gγ chains and circumstantial evidence indicates that these are the products of the same chromosome that carries the Greek HPFH determinant. Hence this chromosome must be directing the synthesis of Gγ, Aγ and (probably) β and δ chains, thus implying that the Greek form of HPFH does not result from a deletion involving the globin chain structural genes. Analysis of the levels and structure of Hb F from the Greek HPFH heterozygotes and from separated cell populations from the Greek HPFH/β thalassaemia compound heterozygotes indicate that the Greek HPFH determinant, while allowing an overall increase in γ chain synthesis, is not the sole factor determining the absolute amount of Hb F production on a cellular basis.

The Corfu δβ thalassaemia mutation in Greece: haematological phenotype and prevalence

Summary The Corfu δβ thalassaemia mutation, a 7.2 kb deletion partially removing the (δ‐globin gene and a single nucleotide mutation (GA) at intervening sequence I (IVSI‐n5) in the β‐globin gene in cis, was first described in a family from Corfu; the carriers for this mutation had the unusual haematological phenotype of heterozygous β‐thalassaemia with normal levels of HbA2.

Tissue oxygenation in patients with hemoglobinopathy H

To evaluate the degree of tissue hypoxia in patients with hemoglobinopathy H disease, whole blood oxygen affinity was estimated and analyzed in 33 patients. Twenty patients with iron deficiency anemia, matched for degree of anemia, served as controls. The results were as follows: Whole blood oxygen equilibrium curves of patients with HbH disease are biphasic because of a combination of the rectangular hyperbolic curve of HbH and the normal sigmoid curve of HbA and are shifted toward the left (P50 3.66 +/- 0.33 kPa). Patients with iron deficiency anemia have right-shifted oxygen equilibrium curves (P50 4.02 +/- 0.13 kPa) compared with normal. Oxygen release to the tissues in HbH disease is decreased (1.4 +/- 0.3 mmol/L) as compared with iron-deficient patients (1.6 +/- 0.2 mmol/L) with a similar degree of anemia. Red cell indices vary between the two groups. In patients with HbH disease the mean corpuscular hemoglobin concentration was 268 +/- 17 g/L as compared with 294 +/- 18 g/L in iron deficiency anemia. These findings indicate that whole blood oxygen affinity is a reliable index of tissue oxygenation in patients with hemoglobinopathy H.