Osmotic gradient ektacytometry: A valuable screening test for hereditary spherocytosis and other red blood cell membrane disorders.

INTRODUCTION: New generation osmotic gradient ektacytometry has become a powerful procedure for measuring red blood cell deformability and therefore for the diagnosis of red blood cell membrane disorders. In this study, we aim to provide further support to the usefulness of osmotic gradient ektacytometry for the differential diagnosis of hereditary spherocytosis by measuring the optimal cutoff values of the parameters provided by this technique. METHODS: A total of 65 cases of hereditary spherocytosis, 7 hereditary elliptocytosis, 3 hereditary xerocytosis, and 171 normal controls were analyzed with osmotic gradient ektacytometry in addition to the routine red blood cell laboratory techniques. The most robust osmoscan parameters for hereditary spherocytosis diagnosis were determined using receiver operating characteristic curve analysis. RESULTS: The best diagnostic criteria for hereditary spherocytosis were the combination of decreased minimal elongation index up to 3% and increased minimal osmolality point up to 5.2% when compared to the mean of controls. Using this established criterion, osmotic gradient ektacytometry reported a sensitivity of 93.85% and a specificity of 98.38% for the diagnosis of hereditary spherocytosis. CONCLUSION: Osmotic gradient ektacytometry is an effective diagnostic test for hereditary spherocytosis and enables its differential diagnosis with other red blood cell membrane diseases based on specific pathology profiles.

ICSH recommendations for identification, diagnostic value, and quantitation of schistocytes.

Schistocytes are fragments of red blood cells (RBCs) produced by extrinsic mechanical damage within the circulation. The detection of schistocytes is an important morphological clue to the diagnosis of thrombotic microangiopathic anemia (TMA). Reporting criteria between different laboratories, however, are not uniform, owing to variability of shape and nature of fragments, as well as subjectivity and heterogeneity in their morphological assessment. Lack of standardization may lead to inconsistency or misdiagnosis, thereby affecting treatment and clinical outcome. The Schistocyte Working Group of the International Council for Standardization in Haematology (ICSH) has prepared specific recommendations to standardize schistocyte identification, enumeration, and reporting. They deal with the type of smear, method of counting, morphological description based on positive criteria (helmet cells, small, irregular triangular, or crescent-shaped cells, pointed projections, and lack of central pallor). A schistocyte count has a definite clinical value for the diagnosis of TMA in the absence of additional severe red cell shape abnormalities, with a confident threshold value of 1%. Automated counting of RBC fragments is also recommended by the ICSH Working Group as a useful complement to the microscope, according to the high predictive value of negative results, but worthy of further research and with limits in quantitation.

ICSH Guideline for worldwide point-of-care testing in haematology with special reference to the complete blood count.

These guidelines provide information on how to develop and manage a point-of-care (POCT) service so that reliable haematology results are produced regardless of where the test is performed. Many of the issues addressed here are relevant to POCT within hospitals or health centres; however, the principles are equally applicable to care in the community and doctors' offices. Other aspects discussed in this guideline are the initiation of the service (including indications for and limitations of a POCT service), staff training, type of haematology equipment selected, the blood results, monitoring of quality, accreditation, safety and cost. Equipment selected should generate results that are comparable to those of the local reference laboratory. If a complete independent evaluation of the POCT device has not been performed, the purchaser should perform a local assessment according to the protocol in this document. A literature search should also be undertaken to find independent peer reviewed evaluations on POCT equipment. Often the ideals discussed here may not be achievable in some developing countries but long-term training and education of POCT workers needs to be supported and constantly kept on government agendas to reach the recommendations advised here. Users should interpret these recommendations for their particular POCT needs and setting.

Chronic non-spherocytic hemolytic anemia associated with severe neurological disease due to gamma-glutamylcysteine synthetase deficiency in a patient of Moroccan origin.

A previously undescribed mutation of hereditary gamma-glutamylcysteine synthetase (GCS) deficiency was found in a 5 year old boy of Moroccan origin. He presented with chronic haemolytic anaemia, delayed psychomotor development and progressive motor sensitive neuropathy of lower extremities. The parents were third degree relatives. The activity of glycolytic enzymes were found to be normal in the propositus, his parents and a sister, but and a complete lack of GSH was found in the propositus. Accordingly, the measurement of de novo GSH synthetic enzymes was undertaken, and severe GCS deficiency was found in the propositus. Both parents and his sister presented GCS activity ranging from 69% to 90% of normal. GCS gene sequencing showed that the propositus was homozygous for a 1241C>T mutation in exon 11 and both parents and his sister were heterozygous. This mutation predicts a Pro414Leu amino acid substitution. Even though the homology between GCS and crystallographically solved, functionally related proteins is not very high, a three-dimensional model of GCS was derived using Modeller Software. GCS deficiency is a very rare autosomal recessive disorder reported so far in only 8 unrelated probands with severe haemolytic anaemia. In only 3 of these was the anaemia associated with severe neurological dysfunction. We report here the fourth case of GCS deficiency presenting neuropathy, giving further support to the eventual relationship between this enzymopathy and neurological damage.

Red cell membrane Na+ transport systems in hereditary spherocytosis: relevance to understanding the increased Na+ permeability.

Red blood cells (RBCs) in hereditary spherocytosis (HS) show high sodium (Na+) and potassium (K+) movement across the membrane, resulting in dehydration. In general, these abnormal cation fluxes have been interpreted as "increased leaks" due to passive or electrodiffusional permeability of the RBC membrane. A study to elucidate the contribution of concomitant ouabain-resistant pathways (Na-K-2Cl cotransport and Na-Li countertransport) to abnormal Na+ permeability present in RBCs of subjects with HS has been undertaken. Accordingly, erythrocyte Na+ and K+ content and transmembrane cation movements via the Na-K pump, Na-K-2Cl cotransport, Na-Li countertransport, and Na+ passive diffusion, were measured in 25 non-splenectomized patients with HS and compared with the results obtained from the study of 11 patients with congenital non-spherocytic haemolytic anaemia (CNSHA) due to hereditary elliptocytosis (7 cases) and RBC enzyme defects (4 cases) and of 30 normal controls. Compared to the controls, patients with HS exhibited a highly significant (P<0.001) increase in all the Na+ transmembrane movements via passive diffusion (411+/-243 vs 105+/-40), Na-K pump (2615+/-970 vs 1874+/-359), Na-K-2Cl cotransport (males: 371+/-138 vs 190+/-42; females: 401+/-134 vs 104+/-44) and Na-Li countertransport (207+/-131 vs 98+/-41). This was associated with increased Na+ and decreased K+ content, resulting in a reduction of total cation (Na+ + K+) RBC concentration. Furthermore, significant correlations were also found between the patients' RBC cationic content and the mean corpuscular haemoglobin concentration (MCHC) (r=0.51, P<0.05) and between the Na+ passive leak and the haematocrit value (r=-0.44, P<0.05). In the patients with CNSHA, a less significant (P<0.01) increase of active (Na-K pump) and passive (leak) transmembrane permeability to Na+ was associated with normal transmembrane movements via Na-K-2Cl cotransport and Na-Li countertransport. The present study demonstrates that in HS, RBCs are characterized by a variable, but always significant increase of all the membrane transport systems leading to the extrusion of Na+, and that these abnormalities, regardless of their relation to membrane structural defects, may probably be valuable for the differential diagnosis between HS and other congenital defects of RBCs.

Co-existence of hereditary spherocytosis and a new red cell pyruvate kinase variant: PK mallorca.

BACKGROUND AND OBJECTIVE: A partial red blood cell (RBC) pyruvate-kinase (PK-R) deficiency was found in a patient with concomitant hereditary spherocytosis (HS) and chronic hemolytic anemia. Clinical, biological and molecular studies were performed in the patient, his parents and a brother, in order to characterize the specific PK-R gene mutation and the inheritance mechanism of the transmission of both red cell defects in this particular family. DESIGN AND METHODS: Conventional biological studies were used to identify the PK-LR gene mutation responsible for hereditary transmission of PK-R deficiency and HS. The family study was completed with genotypic and RBC membrane protein analyses in the patient and his family. RESULTS: Molecular study of the PK deficiency was performed in all the family members and demonstrated a heterozygous condition for the 1516 G->A (506Val->Ile) mutation at the PK-LR gene in both the patient and his mother. Since this mutation has not been reported previously, it is provisionally named PK "Mallorca". The study of RBC membrane proteins demonstrated the existence of partial band 3 and protein 4.2 deficiencies in the propositus and his father but not in the mother and brother, who were also studied. These results support the dominant mode of inheritance of HS and PK-LR gene in this family. INTERPRETATION AND CONCLUSIONS: HS and PK deficiency are not exceptional in Spain. The co-existence of both RBC defects in the same patient, however, is very rare; only a few cases have been described to date. Our findings suggest that performing an elementary RBC enzyme survey in all patients with HS would help to determine the real frequency of this apparently rare association.

[Molecular study of red cell pyruvate kinase deficiency in 15 patients with chronic hemolytic anemia. Group of Erythropathology of Hematology and hemotherapy Association of Spain (HHAS)]. / Estudio molecular del déficit de piruvatocinasa eritrocitaria en 15 pacientes con anemia hemolítica crónica. Grupo de Eritropatología de la Asociación Española de Hematología y Hemoterapia (AEHH).

BACKGROUND: Identification of RBC pyruvate-kinase (PK) gene mutations by polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) followed by PK gene sequencing in positive cases has been assessed and the results obtained with a preliminary study of 15 unrelated patients of Spanish origin are presented. PATIENTS AND METHODS: Patients have been classified into two different groups: group 1, propositus (15 cases), and group 2, relatives of the patients included in group 1 (10 males and 5 females). In group 1, a PCR was followed by SSCP and sequencing, and in group 2, the PCR was followed by digestion with specific restriction endonucleases (PCR-ER). RESULTS: Group 1: from 15 patients included in the study 2 were identified as homozygous, 4 as heterozygous and 9 as compound heterozygous. In this group, were identify 26 affected alleles with 11 different mutations: T1456 10 alleles (38.6%), T721 3 alleles (11.6%), A1010, C514, C1015 and T1223 2 alleles (7.7%), and C1070, A1291, T1508, A1595 y T1675 one allele. Relatives from 8 out of 15 patients from group 1 showed the following pattern: homozygous (one case), heterozygous (10 cases), compound heterozygous (2 cases) and normal (2 cases). CONCLUSIONS: SSCP procedure followed by direct gene sequencing in positive cases is fast and simple enough to allow the identification of PK deficient variants, avoiding the need of biochemical characterisation of semipurified deficient enzyme, which is more cumbersome and time consuming. In addition, the PCR-ER method is a very useful tool for screening of the most frequent molecular variants, as well as, for the detection of the carrier condition of this enzymopathy (family studies).

Molecular characterization of the PK-LR gene in pyruvate kinase deficient Spanish patients. Red Cell Pathology Group of the Spanish Society of Haematology (AEHH).

The PK-LR gene has been studied in 12 unrelated patients with red cell pyruvate kinase deficiency and hereditary nonspherocytic haemolytic anaemia (CNSHA). The entire codifying region of the R-type PK gene and the flanking intronic regions were analysed by single-stranded conformation polymorphism (SSCP) followed by direct sequencing of abnormal DNA. 10 different mutations were identified in 22/24 alleles at risk. Eight of these were missense mutations that caused the following single amino acid changes: G514C (172Glu-Gln), G1010A (337Arg-Gln), G1015C (339Asp-Gln), T1070C (357Ile-Thr), C1223T (408Thr-Ile), G1291A (431Ala-Thr), C1456T (486Arg-Trp) and G1595A (532Arg-Gln). Two were nonsense mutations: G721T (241Glu-Stop) and C1675T (559Arg-Stop). 7/22 alleles demonstrated the same C1456 --> T mutation. The study of the polymorphic site at nucleotide (nt) 1705 performed in all cases disclosed a 1705 C/C mutation in 10 and a 1705 A/C mutation in three. This is the first report on the presence of several different L-type PK gene mutations within Spanish population. Furthermore, from the PK gene mutations found, six were unique and not previously described (1015C, 1070C, 1223T, 1291A, 1595A and 1675T) and one (C1456T) seems to be predominant in Spain. Interestingly, no case with the 1529A mutation commonly found in Northern European populations was present here.

Two new mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene associated with haemolytic anaemia: clinical, biochemical and molecular relationships.

In two unrelated Spanish males with glucose-6-phosphate dehydrogenase (G6PD) deficiency and haemolytic anaemia, and two different novel point mutations in the G6PD gene, have been identified. A C to T transition at nucleotide 406 resulting in a (136) Arg to Cys substitution and a C to G transition at nucleotide 1155 resulting in a (385) Cys to Trp substitution. These two molecular defects have not been described before and are designated G6PD Valladolid 406 C-->T and G6PD Madrid 1155 C-->G. In vitro biochemical characterization of both mutant enzymes showed important differences in their molecular properties according to their different clinical behaviour. In G6PD Valladolid, the mutation of which is located in exon 5, the normal in vitro heat stability may explain its mild clinical expression (low-grade haemolysis interrupted by an acute haemolytic crisis at age 70). In G6PD Madrid, the mutation, located in exon 10, results in a deficient variant associated with neonatal jaundice and life-long chronic nonspherocytic haemolytic anaemia (CNSHA). This finding further emphasizes the importance of this specific region of the G6PD gene in the stabilization of the G6PD molecule. Putative relationships between these single point mutations and the molecular properties of the mutant enzymes are also discussed.

First description of a frameshift mutation in the alpha1-globin gene associated with alpha-thalassaemia.

A frameshift mutation in the alpha1-globin gene, responsible for a clinically mild alpha-thalassaemia phenotype, has been characterized in a Spanish woman. After excluding the most common forms of alpha-thalassaemia found in the Mediterranean area, both alpha-globin genes (alpha1 and alpha2) were amplified and analysed selectively by non-radioactive single-strand conformation polymorphism (SSCP). An abnormal SSCP mobility was present in the second exon of the alpha1-globin gene and direct sequence analysis revealed a 13 bp deletion (between codons 51 and 55) affecting a single allele. The consequence of this mutation is a reading frameshift leading to a novel amino acid coding sequence from codons 51-61 and a premature stop signal at new position 62, which results in a net reduction of the affected alpha-globin chain output. The presence of this new mutation was confirmed by restriction enzyme analysis of the specific PCR product.

[Hemopoietic progenitor cell transplantation: 20 years' experience at the Hematology School "Farreras-Valentí"/Clinical Hospital of Barcelona]. / Trasplante de progenitores hemopoyéticos: 20 años de experiencia en la Escuela de Hematología "Farreras-Valentí"/Hospital Clínic de Barcelona.

BACKGROUND: Hemopoietic progenitor cell transplantation (HPCT) is acquiring an increasing role in the therapy for a variety of disorders. In this study, main characteristics and results of HPCT along 20 years are analyzed from the experience of Postgraduate School of Hematology "Farreras-Valentí" at the Hospital Clínic in Barcelona. PATIENTS AND METHODS: Six-hundred ninety-five patients transplanted between June 1976 and January 1996 were analyzed. Median age (range) were 33 (4-63) years. The following aspects were considered: donor type, source or progenitor cells, type of disease and disease-stage at transplantation, transplant related mortality and survival. RESULTS: A total of 714 HPCT were performed (448 allogeneic, 13 isogeneic, 253 autogeneic). Allogeneic HPCT were from an HLA-identical sibling in 408 cases, from other familial donors in 10, and from non-familial donors in 30. Most HPCT from non-familial donors (93%) were performed during the last five years of the study (1991-1995). The source of hemopoietic progenitor cells was bone marrow in 625 instances (88%), peripheral blood in 88 (12%), and fetal liver in one. During more than 15 years, the only source of progenitors was the bone marrow; in contrast, in the last 3 years (1993-1995) transplants using peripheral blood were predominant. Main indications for HPCT were the following: acute leukemias (n = 387) (54%), chronic leukemias (n = 134) (19%), severe aplastic anemia (n = 58) (8%), lymphomas (n = 80) (11%), multiple myeloma (n = 39) (5%) and myelodysplastic syndromes (n = 14) (2%). In patients with hematological malignancies (n = 656), HPCT was performed in first complete remission or in first chronic phase in 321 instances (49%), in subsequent remissions in 144 (22%), and in more advanced stages in the remaining 191 (29%). In the more recent years, a progressive decrease in the number of HPCT for acute leukemia or aplastic anemia was observed, contrasting with an increase in transplants for lymphoma, multiple myeloma and myelodysplastic syndromes. Of note, a significant decrease in transplant related mortality was evident along the years, both after autogeneic HPCT (21% during 1985-1992 and 6% thereafter) (p = 0.001) and after allogeneic transplantation (54%, 44%, and 20% during the periods 1976-1984, 1985-1992 and 1993-1995, respectively) (p = 0.004). The fact translated into an increase in the actuarial probability of survival after allogeneic HPCT (25%, 33% and 58% in the three mentioned periods, respectively) (p = 0.0003), and after autogeneic HPCT (33% in the interim 1985-1992, and 55% in the period 1993-1995) (p = 0.001). CONCLUSIONS: During the last 20 years, HPCT has significantly evolved in aspects such as type of donor, source of progenitor cells and indications. Remarkably, a progressive decrease in transplant related mortality has been observed translating into a improvement in survival after the procedure.

[Evaluation of the Coulter MAXM. Differential leukocyte count and left-shift alarm]. / Evaluación del autoanalizador hematológico Coulter MAXM. Recuento diferencial leucocitario y alarma de desviación a la izquierda.

PURPOSE: To assess the reliability of the differential leucocyte count (DLC) and the left shift flagging (LSF) system provided by the Coulter MAXM (MAXM) haematology analyzer. MATERIAL AND METHODS: 380 blood specimens (drawn with tri-K EDTA as anticoagulant) were studied. RESULTS: By using the reference method (NCCLS H20-A), 50 out of the 380 blood specimens presented abnormal DLC (bands > 6%). Of from these, in 39 (80%) the MAXM displayed LSF of "bands 1 or 2". In 118 left shift flagged specimens (MAXM) with normal manual DLC, 87 (74%) had the "bands 1" alarm and 31 (26%) the "bands 2" alarm. Accordingly if the LSF "bands 1" is overlooked, the percentage of FP decreases from 36% to 10% but the percentage of false negatives (FN) increases from 22% to 58%. In order to improve the appreciation of LSF by decreasing the need of manual revisions, the visual examination of the leucocyte distribution scattergram (LDS), also provided by the MAXM, was conveniently evaluated. This study was performed on 190 blood specimens from which the MAXM displayed a normal DLC in 122 (64%), the LSF of "bands" in 44 (23%) and the LSF of "bands 2" in 24 (12.6%). Of from the 122 specimens with normal DLC, four were FN, of from the 44 specimens with "bands 1" LSF, 37 were FP and of from the 24 specimens with "bands 2" LSF, 16 were FP. The visual appreciation of the LDS showed in the majority of samples with "bands 1" and "bands 2" a definitely different shape consisting in a sharper image up to the top of the picture when compared to samples with normal DLC (without flags). According to this criteria, all the 122 specimens with normal DLC displayed a normal LDS and all the 24 specimens with "bands 2" flag displayed abnormal LDS. Of from the 44 specimens with "bands 1" flag, 26 (59%) showed an abnormal LDS and 18 (41%) a normal LDS. It is noteworthy that of from the 26 specimens with abnormal LDS only 7 were true positive (TP), whereas the 18 specimens with normal LDS all showed a normal DLC according to the reference method. These data allow us to conclude that manual revision was required in 26 out of 68 specimens with "bands 1" and abnormal LDS (13% of the total) and in all the 24 specimens with "bands 2" flag. Therefore by using the information provided by the LDS the need of manual revision decreases to 73% of the total sample with LSF. CONCLUSION: Our results give further support to the idea that th VCS method used by the Coulter MAXM provides a high quality DLC with specific left shift detection.

[Molecular analysis of glucose-6-dehydrogenase deficiency in Spain]. / Análisis molecular del déficit de glucosa-6-fosfato deshidrogenasa (G6PD) en España.

PURPOSE: G6PD deficiency is the most frequent enzymopathy-producing genetic polymorphism in humans. Up to now, over 400 putative variants of G6PD have been distinguished on the basis of biochemical characterization of the deficient enzyme. Analysis of the G6PD gene has made possible a precise classification of the G6PD molecular variants by identification of about 80 different point mutations causing much of the phenotypic heterogeneity. In the Spanish population, the analysis of G6PD has led to the identification of 15 different point mutations that underlay the phenotypic heterogeneity of G6PD previously reported by biochemical analysis. The purpose of the study has been to identify the genetic mutation responsible of the G6PD deficiency and to improve the knowledge of its genetic homogeneity. PATIENTS AND METHODS: From 50 Spanish males with G6PD deficiency 34 came from out consultation and 16 from the Spanish Study Group on Red Cell Pathology (GEHBTA-Eritropatología) The methods employed included screening of prevalent mutations by ER-PCR, SSCP-PCR, genetic segmentation and biochemical characterization of the deficient enzyme. RESULTS: In 31 cases the mutations were characteristic of the four most frequent polymorphic variants found in Spain (G6PD A-376G/202A, G6PD Mediterranean 563T G6PD Union 1360T and G6PD Seattle 344C). Since these mutations either create or abolish a specific site recognized by a restriction endonuclease (RE), they can be rapidly detected by RE digestion of a PCR-amplified product (PCR-RE). In patients where none of these mutations were present (17 cases), the G6PD gene was subjected to PCR single-strand conformation polymorphism (PCR-SSCP) analysis combined with direct PCR-sequencing. By using this procedure, 9 new mutations have been identified, five of them have been also found in other geographical areas and were associated with favism (G6PD A-376G/968C, G6PD Santamaria 376G/542T, G6PD Aures 143C and G6PD Chatham 1003A) or chronic haemolytic anaemia (G6PD Tomah 1153C). The other four mutations are unique and not reported so far: Three of them are associated with favism (G6PD Málaga 542T, G6PD Murcia 209G and G6PD Valladolid 406T) and one with chronic haemolytic anaemia (G6PD Madrid 1155G). The remaining eight cases are under study. CONCLUSION: The present study confirms the marked genetic heterogeneity of G6PD deficiency in Spain and demonstrate that the PCR-RE analysis is an easy tool for rapid diagnosis of the molecular defect in subjects with the common forms of G6PD deficiency. Furthermore the fact that G6PD A-376G/202A is the most common variant within Spanish population and the finding of G6PD Aures 43C and G6PD Santamaría 76G/542T, who are polymorphic in Algeria is consistent with a significant gene flow from Africa to Europe through Spain.

Congenital 6-phosphogluconate dehydrogenase (6PGD) deficiency associated with chronic hemolytic anemia in a Spanish family.

Clinical and metabolic studies were performed in four members of a Spanish family with partial (50%) 6 phosphogluconate dehydrogenase (6PGD) deficiency. In all cases the activities of 6 phosphogluconolactone (6PGL) and glutathione reductase (GR) were normal, and the molecular characterization performed in the partially purified 6PGD from the propositus showed normal kinetic and electrophoretic patterns. Two females (the propositus and her sister) suffered from a well-compensated chronic nonspherocytic hemolytic anemia (CNSHA) and exhibited decreased RBC glutathione (GSH) stability with increased oxidative susceptibility, defined by enhanced malonyldialdehyde (MDA) generation "in vitro." The other two members of the family (the propositus's mother and brother) were clinically asymptomatic. In the propositus and her sister, RBC metabolism exhibited a markedly abnormal concentration of glycolytic intermediates, mainly characterized by striking increases in fructose 1,6 bisphosphate (50-fold), dihydroxiacetone-phosphate (20-fold) and glyceraldehyde 3-phosphate (tenfold). Although the precise mechanism of the hemolysis in the two patients is unknown, the enhanced oxidative threat observed in their RBCs may interfere in some way with the glycolytic pathway function, leading to a marked increase in certain metabolic intermediates located before the glyceraldehyde 3 phosphate dehydrogenase (GA3PD) step. Since it seems that GA3PD half-life is modulated by fluctuations of the cytosolic redox status, an "in situ" approach was simulated by using permeabilized RBCs. In these conditions, GA3PD activity was significantly lower in the propositus and her sister than in the asymptomatic members of the family and the simultaneous normal control.

Haemoglobin Lleida: a new alpha 2-globin variant (12 bp deletion) with mild thalassaemic phenotype.

Molecular studies of alpha-thalassaemias have revealed defects at different steps in the process of alpha-gene expression. It is not surprising, therefore, that in some cases a single mutation or small deletion can result in a structurally abnormal haemoglobin that produces the alpha-thalassaemia phenotype. In this report we describe a new unstable alpha-globin variant, Hb Lleida, in a Spanish patient with alpha-thalassaemia trait. The mutation was detected by single-strand conformation polymorphism in the third exon of the alpha 2-globin gene. Direct sequence analysis of the alpha-globin gene showed a 12 bp deletion as the only defect of the alpha 2- and alpha 1-globin genes. The propositus was revealed to be a heterozygous carrier, and two alleles were separated by electrophoresis. This deletion causes the loss of four aminoacid residues (from codon 113 to 116) and would be expected to produce an unstable haemoglobin, as a shorter alpha-globin chain variant is created with 137 amino acids instead of 141 amino acids present in a normal alpha-globin chain. However, no abnormal haemoglobin was found by either isoelectric focusing or haemoglobin electrophoresis. Since the deletion affects an aminoacid residue (114 Pro) involved in alpha 1-beta 1-globin chain contacts, the interaction required for efficient Hb assembly is also compromised. The resulting unstable alpha-globin chain is rapidly catabolized and unsuitable for haemoglobin tetramer formation, causing an alpha-thalassaemia trait phenotype in the heterozygous patient.

Detection of circulating neoplastic cells by reverse-transcriptase polymerase chain reaction in malignant melanoma: association with clinical stage and prognosis.

PURPOSE: Circulating melanoma cells can be detected in peripheral blood by means of tyrosinase mRNA amplification by reverse-transcriptase polymerase chain reaction (RT-PCR). We conducted a prospective study to evaluate the clinical significance of the presence of circulating neoplastic cells in the blood of patients with malignant melanoma (MM). METHODS: A sensitive RT-PCR assay was used to detect tyrosinase mRNA in the peripheral blood of patients with stages I to IV melanoma. Healthy subjects or patients with other malignancies were used as negative controls. RESULTS: Ninety-one assessable patients were included in the study. There was a statistically significant association between RT-PCR positivity and clinical stage. Circulating melanoma cells were detected in 36% of patients with localized disease (stages I and II), in 45% of patients with regional nodal involvement (stage III), and in 94% of patients with metastatic disease (stage IV) (P < .001). In stage II-III patients who were RT-PCR-positive for mRNA tyrosinase in blood, the recurrence rate and disease-free survival were significantly worse than patients who were RT-PCR-negative. In multivariate analysis, RT-PCR was an independent prognostic factor for recurrence in patients with nonmetastatic disease (P = .002). CONCLUSION: The detection of circulating melanoma cells in peripheral blood by RT-PCR correlated with the clinical stage of patients with melanoma and was an independent prognostic factor for recurrence. Further studies are warranted to better assess the significance of this test in the evaluation of prognosis, early detection of relapse, and in monitoring the effectiveness of systemic therapy.