Current Status of Molecular Diagnosis of Hereditary Hemolytic Anemia in Korea

Hereditary hemolytic anemia (HHA) is considered a group of rare hematological diseases in Korea, primarily because of its unique ethnic characteristics and diagnostic challenges. Recently, the prevalence of HHA has increased in Korea, reflecting the increasing number of international marriages and increased awareness of the disease. In particular, the diagnosis of red blood cell (RBC) enzymopathy experienced a resurgence, given the advances in diagnostic techniques. In 2007, the RBC Disorder Working Party of the Korean Society of Hematology developed the Korean Standard Operating Procedure for the Diagnosis of Hereditary Hemolytic Anemia, which has been continuously updated since then. The latest Korean clinical practice guidelines for diagnosing HHA recommends performing next-generation sequencing as a preliminary step before analyzing RBC membrane proteins and enzymes. Recent breakthroughs in molecular genetic testing methods, particularly next-generation sequencing, are proving critical in identifying and providing insight into cases of HHA with previously unknown diagnoses. These innovative molecular genetic testing methods have now become important tools for the management and care planning of patients with HHA. This review aims to provide a comprehensive overview of recent advances in molecular genetic testing for the diagnosis of HHA, with particular emphasis on the Korean context.

Transient presence of stomatocytes: A clue to the diagnosis of overhydrated hereditary stomatocytosis in a child with beta-thalassemia

BACKGROUND

Overhydrated hereditary stomatocytosis (OHSt) is a rare disorder characterized by abnormalities in erythrocytic volume homeostasis. Early and accurate diagnosis is essential for appropriate management and genetic counseling.

METHODS

We present the case of a child with beta-thalassemia and a history of multiple blood transfusions. Clinical presentation, laboratory findings, and genetic testing were reviewed. Peripheral blood smear examination and genetic analysis were performed.

RESULTS

The patient was admitted with severe anemia, and peripheral blood smear examination revealed the presence of up to 50% stomatocytes. Laboratory investigations showed abnormalities in red blood cell parameters, including decreased hemoglobin levels and increased mean corpuscular volume. Genetic testing identified a heterozygous mutation in the RHAG gene, confirming the diagnosis of OHSt. The presence of stomatocytes in the peripheral blood smear was transient, correlating with episodes of hemolysis and its control.

Diagnostic yield of targeted next-generation sequencing for pediatric hereditary hemolytic anemia

BACKGROUND

Hereditary hemolytic anemia (HHA) refers to a heterogeneous group of genetic disorders that share one common feature: destruction of circulating red blood cells (RBCs). The destruction of RBCs may be due to membranopathies, enzymopathies, or hemoglobinopathies. Because these are genetic disorders, incorporation of next-generation sequencing (NGS) has facilitated the diagnostic process of HHA.

METHOD

Genetic data from 29 patients with suspected hereditary anemia in a tertiary hospital were retrospectively reviewed to evaluate the efficacy of NGS on hereditary anemia diagnosis. Targeted NGS was performed with custom probes for 497 genes associated with hematologic disorders. After genomic DNA was extracted from peripheral blood, prepared libraries were hybridized with capture probes and sequenced using NextSeq 550Dx (Illumina, San Diego, CA, USA).

RESULT

Among the 29 patients, ANK1 variants were detected in five, four of which were pathogenic or likely pathogenic variants. SPTB variants were detected in six patients, five of which were classified as pathogenic or likely pathogenic variants. We detected g6pd pathogenic and spta1 likely pathogenic variants in two patients and one patient, respectively. Whole-gene deletions in both HBA1 and HBA2 were detected in two patients, while only HBA2 deletion was detected in one patient. One likely pathogenic variant in PLKR was detected in one patient, and one likely pathogenic variant in ALAS2 was detected in another.

CONCLUSION

Here, NGS played a critical role in definitive diagnosis in 18 out of 29 patients (62.07%) with suspected HHA. Thus, its incorporation into the diagnostic workflow is crucial.

Diagnosis and clinical management of red cell membrane disorders

Heterogeneous red blood cell (RBC) membrane disorders and hydration defects often present with the common clinical findings of hemolytic anemia, but they may require substantially different management, based on their pathophysiology. An accurate and timely diagnosis is essential to avoid inappropriate interventions and prevent complications. Advances in genetic testing availability within the last decade, combined with extensive foundational knowledge on RBC membrane structure and function, now facilitate the correct diagnosis in patients with a variety of hereditary hemolytic anemias (HHAs). Studies in patient cohorts with well-defined genetic diagnoses have revealed complications such as iron overload in hereditary xerocytosis, which is amenable to monitoring, prevention, and treatment, and demonstrated that splenectomy is not always an effective or safe treatment for any patient with HHA. However, a multitude of variants of unknown clinical significance have been discovered by genetic evaluation, requiring interpretation by thorough phenotypic assessment in clinical and/or research laboratories. Here we discuss genotype-phenotype correlations and corresponding clinical management in patients with RBC membranopathies and propose an algorithm for the laboratory workup of patients presenting with symptoms and signs of hemolytic anemia, with a clinical case that exemplifies such a workup.

Molecular heterogeneity of pyruvate kinase deficiency

Red cell pyruvate kinase (PK) deficiency is the most common glycolytic defect associated with congenital non-spherocytic hemolytic anemia. The disease, transmitted as an autosomal recessive trait, is caused by mutations in the PKLR gene and is characterized by molecular and clinical heterogeneity; anemia ranges from mild or fully compensated hemolysis to life-threatening forms necessitating neonatal exchange transfusions and/or subsequent regular transfusion support; complications include gallstones, pulmonary hypertension, extramedullary hematopoiesis and iron overload. Since identification of the first pathogenic variants responsible for PK deficiency in 1991, more than 300 different variants have been reported, and the study of molecular mechanisms and the existence of genotype-phenotype correlations have been investigated in-depth. In recent years, during which progress in genetic analysis, next-generation sequencing technologies and personalized medicine have opened up important landscapes for diagnosis and study of molecular mechanisms of congenital hemolytic anemias, genotyping has become a prerequisite for accessing new treatments and for evaluating disease state and progression. This review examines the extensive molecular heterogeneity of PK deficiency, focusing on the diagnostic impact of genotypes and new acquisitions on pathogenic non-canonical variants. The recent progress and the weakness in understanding the genotype-phenotype correlation, and its practical usefulness in light of new therapeutic opportunities for PK deficiency are also discussed.

Epidemiological Study of Hereditary Hemolytic Anemia in the Korean Pediatric Population during 1997-2016: a Nationwide Retrospective Cohort Study

BACKGROUND

Hereditary hemolytic anemia (HHA) is a rare disease characterized by premature red blood cell (RBC) destruction due to intrinsic RBC defects. The RBC Disorder Working Party of the Korean Society of Hematology established and updated the standard operating procedure for making an accurate diagnosis of HHA since 2007. The aim of this study was to investigate a nationwide epidemiology of Korean HHA.

METHODS

We collected the data of a newly diagnosed pediatric HHA cohort (2007-2016) and compared this cohort's characteristics with those of a previously surveyed pediatric HHA cohort (1997-2006) in Korea. Each participant's information was retrospectively collected by a questionnaire survey.

RESULTS

A total of 369 children with HHA from 38 hospitals distributed in 16 of 17 districts of Korea were investigated. RBC membranopathies, hemoglobinopathies, RBC enzymopathies, and unknown etiologies accounted for 263 (71.3%), 59 (16.0%), 23 (6.2%), and 24 (6.5%) of the cases, respectively. Compared to the cohort from the previous decade, the proportions of hemoglobinopathies and RBC enzymopathies significantly increased (P < 0.001 and P = 0.008, respectively). Twenty-three of the 59 hemoglobinopathy patients had immigrant mothers, mostly from South-East Asia.

CONCLUSION

In Korea, thalassemia traits have increased over the past 10 years, reflecting both increased awareness of this disease and increased international marriages. The enhanced recognition of RBC enzymopathies is due to advances in diagnostic technique; however, 6.5% of HHA patients still do not have a clear diagnosis. It is necessary to improve accessibility of diagnosing HHA.

Whole-exome analysis to detect congenital hemolytic anemia mimicking congenital dyserythropoietic anemia

Congenital dyserythropoietic anemia (CDA) is a heterogeneous group of rare congenital disorders characterized by ineffective erythropoiesis and dysplastic changes in erythroblasts. Diagnosis of CDA is based primarily on the morphology of bone marrow erythroblasts; however, genetic tests have recently become more important. Here, we performed genetic analysis of 10 Japanese patients who had been diagnosed with CDA based on laboratory findings and morphological characteristics. We examined 10 CDA patients via central review of bone marrow morphology and genetic analysis for congenital bone marrow failure syndromes. Sanger sequencing for CDAN1, SEC23B, and KLF1 was performed for all patients. We performed whole-exome sequencing in patients without mutation in these genes. Three patients carried pathogenic CDAN1 mutations, whereas no SEC23B mutations were identified in our cohort. WES unexpectedly identified gene mutations known to cause congenital hemolytic anemia in two patients: canonical G6PD p.Val394Leu mutation and SPTA1 p.Arg28His mutation. Comprehensive genetic analysis is warranted for more effective diagnosis of patients with suspected CDA.

Congenital Hemolytic Anemia

Red blood cell (RBC) destruction can be secondary to intrinsic disorders of the RBC or to extrinsic causes. In the congenital hemolytic anemias, intrinsic RBC enzyme, RBC membrane, and hemoglobin disorders result in hemolysis. The typical clinical presentation is a patient with pallor, anemia, jaundice, and often splenomegaly. The laboratory features include anemia, hyperbilirubinemia, and reticulocytosis. For some congenital hemolytic anemias, splenectomy is curative. However, in other diseases, avoidance of drugs and toxins is the best therapy. Supportive care with transfusions are also mainstays of therapy. Chronic hemolysis often results in the formation of gallstones, and cholecystectomy is often indicated.

[Proliferative glomerulonephritis and erythroblastopenia associated with Bartonella quintana endocarditis]

Bartonella quintana is a facultative intracellular bacteria responsible of negative blood culture endocarditis whose diagnosis is often delayed. The occurrence of renal involvement has been exceptionally described in this context. We report the case of a 54-year-old man presenting with Bartonella quintana endocarditis complicated by proliferative glomerulonephritis with acute kidney injury and erythroblastopenia.

Diagnosis and management of rare congenital nonimmune hemolytic disease

Rare, congenital nonimmune hemolytic disorders of the erythrocyte, although uncommon, are important causes of anemia in the child and adult. These are a heterogeneous group of diseases that disrupt normal erythrocyte structure and function in varying ways. Predominant are abnormalities of hemoglobin stability, defects of erythrocyte metabolism, and disorders of erythrocyte hydration. Unstable hemoglobinopathies may lead to chronic or episodic hemolysis. Perturbation of critical enzymes of the Embden-Meyerhof pathway lead to altered erythrocyte metabolism and chronic hemolysis. Disorders of erythrocyte hydration are an under-recognized cause of hemolytic anemia. Beyond pathophysiologic mechanisms of disease, clinical, laboratory, and genetic heterogeneity characterize this group of disorders. Often, they are underdiagnosed or misdiagnosed. This review discusses pathophysiology, inheritance, clinical findings, laboratory manifestations, and management considerations in several rare nonimmune hemolytic diseases including the unstable hemoglobins, disorders of erythrocyte metabolism, and abnormalities of erythrocyte hydration.

Congenital dyserythropoietic anemia type 1 with a novel mutation in the CDAN1 gene previously diagnosed as congenital hemolytic anemia

The congenital dyserythropoietic anemias (CDAs) are a heterogeneous group of genetic disorders of red cell production. They are characterized by ineffective erythropoiesis and dyserythropoiesis. Here, we present the clinical description and mutation analysis of a Japanese female with CDA type 1. She has long been diagnosed with unclassified congenital hemolytic anemia from the neonatal period. However, bone marrow morphology and genetic testing of the CDAN1 gene at the age of 12 years confirmed the afore-mentioned diagnosis. Thus, we should be aware of the possibility of CDA if the etiology of congenital anemia or jaundice cannot be clearly elucidated.

The direct antiglobulin test: a critical step in the evaluation of hemolysis

The direct antiglobulin test (DAT) is a laboratory test that detects immunoglobulin and/or complement on the surface of red blood cells. The utility of the DAT is to sort hemolysis into an immune or nonimmune etiology. As with all tests, DAT results must be viewed in light of clinical and other laboratory data. This review highlights the most common clinical situations where the DAT can help classify causes of hemolysis, including autoimmune hemolytic anemia, transfusion-related hemolysis, hemolytic disease of the fetus/newborn, drug-induced hemolytic anemia, passenger lymphocyte syndrome, and DAT-negative hemolytic anemia. In addition, the pitfalls and limitations of the test are addressed. False reactions may occur with improper technique, including improper washing, centrifugation, and specimen agitation at the time of result interpretation. Patient factors, such as spontaneous red blood cell agglutination, may also contribute to false results.

The diagnostic dilemma of congenital unstable hemoglobinopathies

Unstable hemoglobin variants represent a rare etiology of congenital hemolytic anemia. Without a high index of suspicion, plus proper laboratory testing and interpretation, the correct diagnosis can be elusive. We report on five children who were initially thought to have other congenital disorders such as hereditary spherocytosis or thalassemia, before β-globin gene sequencing led to the definitive diagnosis. Recognizing the variable clinical presentation and laboratory data reported will aid clinicians in diagnosis of unstable hemoglobins variants in children with atypical forms of hemolytic anemia, particularly those with low pulse oximetry values or whose hemoglobin electrophoresis suggest β-thalassemia trait.

Haemolytic anaemia in alcohol abuse. A review of 14 cases

Clinical and haematological data on 14 patients (8 women and 6 men) with alcohol-induced haemolytic anaemia and mild to moderate liver injury are presented. Nine of the patients were obvious drinkers, while 5 were socially well adjusted individuals in whom alcohol dependence was not suspected on admission to hospital. Four patients presented with a typical Zieve's syndrome. Two further patients had a moderate transient stomatocytosis, as assessed by microscopy of dried blood smears and by scanning electron microscopy. The majority of the patients, however, did not fit into any of the syndromes proposed in the literature. Indeed, the validity of both Zieve's syndrome and the "transient stomatocytosis with hemolysis" syndrome is questioned.

Peas, beans, and the Pythagorean theorem - the relevance of glucose-6-phosphate dehydrogenase deficiency in dermatology

Glucose-6-phosphate (G6PD) deficiency is a common disease characterized by acute hemolysis induced by oxidative stress. More than 400 million subjects throughout the world carry the hereditary enzyme defect with the highest prevalences in Africa, Asia, and the Mediterranean region. In individuals affected by the erythrocytic enzymatic disorder, besides infectious diseases and diet, acute hemolytic crisis can be triggered by numerous drugs frequently used for the treatment of dermatoses. Taking into account the increasing number of immigrants from geographic regions with high prevalences of G6PD deficiency, dermatologists should be alert to the presence of disease.

Partial splenectomy for children with congenital hemolytic anemia and massive splenomegaly

Partial splenectomy is an alternative to total splenectomy for the treatment of congenital hemolytic anemias (CHAs) in children, although the feasibility of this technique in the setting of massive splenomegaly is unknown. This study was designed to evaluate the safety and efficacy of partial splenectomy in children with CHAs and massive splenomegaly. This retrospective study examined 29 children with CHAs who underwent partial splenectomy. Children were divided into 2 groups based on splenic size: 8 children had splenic volumes greater than 500 mL, whereas 21 children had splenic volumes less than 500 mL. Outcome variables included perioperative complications, transfusion requirements, hematocrits, reticulocyte counts, bilirubin levels, splenic sequestration, and splenic regrowth. All 29 children underwent successful partial splenectomy with 0.02 to 10 years of follow-up. After partial splenectomy, children overall had decreased transfusion requirements, increased hematocrits, decreased bilirubin levels, decreased reticulocyte counts, and elimination of splenic sequestration. Children with massive splenomegaly had similar outcomes compared with children without massive splenomegaly. Long-term complications included 3 mild infections, 4 cases of gallstones requiring cholecystectomy, and 1 child who required completion splenectomy. Partial splenectomy is a safe, effective, and technically feasible option for children with various CHAs, even in the setting of massive splenomegaly.

[Anemia, this time without iron deficiency]

The approach to anemia by the primary care physician is to diagnose treatable causes like nutritional deficiencies, renal insufficiency, chronic inflammatory disease or hemolysis. Measurement of reticulocytes allows a distinction of hemolytic and non-hemolytic anemia. Among hemolytic anemias it is important to recognize rare but potentially severe diseases as autoimmune hemolytic anemia, microangiopathic anemia and certain hereditary anemias. Non-hemolytic anemias can be categorized in microcytic, normocytic and macrocytic subtypes. This allows a rational stepwise approach for each category. Most anemias can be correctly classified, evaluated for underlying disease and treated by the primary care physician.

Hemoglobin Hammersmith [beta 42(CD1) Phe --> Ser] causing severe hemolytic anemia in a Japanese girl

Hemoglobin Hammersmith, a rare, unstable hemoglobin variant, was diagnosed in a 9-year-old Japanese girl. She presented with the typical manifestations of this disorder, including neonatal hyperbilirubinemia, followed by progressive hepatosplenomegaly, jaundice, and bilirubinuria. Because of severe hemolytic anemia, she received transfusions of red blood cells every 3 to 4 weeks. However, she underwent splenectomy at the age of 4 years and has continued to be in partial remission without requiring further transfusions. DNA sequence analysis of the polymerase chain reaction-amplified beta-globin gene revealed a point mutation (T --> C) in the second nucleotide of the 42nd codon of the beta-globin chain (beta 42(CD1) Phe --> Ser).

[Diagnosis and gene analysis of congenital hemolytic anemia]

Congenital hemolytic anemia is relatively uncommon and tends to be left undiagnosed because unusual special tests outside health insurance adaptation are needed for the diagnosis. To diagnose properly these patients, we instituted a comprehensive examination system for hemolytic anemia in Fukuoka University Hospital in 1990. In addition to basic laboratory tests, investigation of hemoglobin, SDS-PAGE analysis of red blood cell membrane proteins, a complete panel of red cell enzyme measurements and gene analysis were included. The red cell enzyme measurements was facilitated by the automation on the COBAS MIRA instrument (NIPPON ROCHE). By such a comprehensive examination, we have identified and confirmed 382 cases of congenital hemolytic anemia which otherwise would have escaped detection during the period October 1990 to September 2005 in our institution. SDS-PAGE procedure contributed to the diagnosis of 24 cases of band 3 deficiency, 13 cases of band 4.2 deficiency and 13 cases of band 4.1 deficiency. Hemoglobin studies uncovered 20 cases of abnormal hemoglobins, 126 cases of beta thalassemia and 7 cases of alpha thalassemia. Red cell enzyme measurements were also contributory to the diagnosis of 29 cases of hemolytic anemia in which enzyme levels were reduced.

The molecular basis of hereditary red cell membrane disorders

The red cell membrane is one of the best known membranes in terms of structure, function and genetic disorders. As any plasma membrane it mediates transport functions. It also provides the erythrocytes with their resilience and deformability. Many of the proteins and the genes performing these functions are known in great detail, although some disease-responsible genes are yet to be elucidated. Basic knowledge has shed light on important groups of genetic disorders. The latter include (i) the disorders of the red cell mechanics: hereditary spherocytosis, hereditary elliptocytosis and poikilocytosis, and (ii) the disorders of the passive flux of the monovalent cations across the membrane: the stomacytoses and allied conditions. Reciprocally, many information have come from genetics abnormalities. We will review the mutation-disease relationship. A number of points will be underscored: widespread weak alleles modulate the expression of the SPTA1 gene, encoding the alpha-chain of spectrin; mutations in the anion exchanger can give rise to an array of distinct nosological entities, including a renal condition; splenectomy is banned in the stomatocytoses; a variety of stomatocyosis is part of a pleiotropic syndrome that may includes perinatal fetal liquid effusions. The diagnosis, follow-up and treatment of the involved diseases have gradually improved.

Hereditary pyrimidine 5'-nucleotidase deficiency: from genetics to clinical manifestations

Hereditary pyrimidine 5'-nucleotidase (P5'N) deficiency is the most frequent abnormality of the red cell nucleotide metabolism causing hereditary non-spherocytic haemolytic anaemia. The disorder is usually characterised by mild-to-moderate haemolytic anaemia associated with the accumulation of high concentrations of pyrimidine nucleotides within the erythrocyte. The precise mechanisms leading to the destruction of P5'N deficient red cells are still unclear. The pyrimidine 5'-nucleotidase type-I (P5'N-1) gene is localised on 7p15-p14 and the cDNA has been cloned and sequenced; 20 mutations have been identified so far in 30 unrelated families, most of them at the homozygous level. Recently, the comparison of recombinant mutants of human P5'N-1 with the wild-type enzyme has enabled the effects of amino acid replacements on the enzyme molecular properties to be determined and help to correlate genotype to clinical phenotype.

[Red cell membrane defects]

Genetic defects of red cell membrane proteins constitute in Europe the most common cause of congenital hemolytic anemias. During the past decennium the defects and the pathogenetic mechanisms have been eludicated. Relatively simple hematologic tests allow for differentiation into groups with different severity of the disease. This allows prognostic assessment and careful risk-benefit evaluation for splenectomy.

Hereditäre Enzymdefekte der Erythrozyten: Glukose-6-Phosphatdehydrogenase-Mangel und Pyruvatkinase-Mangel

Als Ursache einer normozytären, hyperregeneratorischen Anämie kommt differentialdiagnostisch neben einer anbehandelten Eisen-, Vitamin B12- oder Folsäuremangelanämie und St.n. Blutverlust eine Hämolyse in Frage. Nach Ausschluss von häufigeren bzw. einfacher abzuklärenden Ursachen für eine Hämolyse wie z.B. immunhämolytischen Anämien, mikroangiopathischen Anämien oder Hämoglobinopathien muss auch ein hereditärer Enzymdefekt der Erythrozyten in Betracht gezogen werden. Weltweit am verbreitetsten ist dabei der Glukose-6-Phosphat-Dehydrogenase-Mangel (G6PD-Mangel). Bei den häufigsten Varianten dieses Enzymmangels tritt eine akute Hämolyse erst unter Stress auf, der z.B. durch Infektionen, «oxidative» Medikamente oder den Genuss von Favabohnen verursacht werden kann. Die schwerste klinische Manifestation bei Glukose-6-Phosphat-Dehydrogenase-Mangel ist der selten auftretende Neugeborenenikterus. Weitere genetische Varianten können eine bei G6PD-Mangel sehr seltene chronische Hämolyse verursachen. Diese wird als chronische nonsphärozytäre hämolytische Anämie beschrieben und kann auch als Folge von anderen Enzymdefekten auftreten. Am häufigsten ist der Pyruvatkinase-Mangel (PK-Mangel). Alle anderen Formen von hereditärem Enzymmangel der erythrozytären Glykolyse sind (noch) deutlich seltener. Dabei ist zu beachten, dass bei gewissen dieser seltenen Formen neurologische und nicht hämatologische Symptome das Krankheitsbild dominieren. Bei Verdacht aufgrund der Klinik und/oder der Familienanamnese kann die Diagnose eines erythrozytären Enzymmangels relativ einfach mittels der Enzymaktivitätsbestimmung gestellt werden. Eine korrekte Diagnosenstellung kann entscheidend für die Wahl der Therapie sein (z.B. Splenektomie bei gewissen Formen). Weiter ist sie von großer Bedeutung für die genetische Beratung, da einige Formen (z.B. der PK-Mangel) autosomal rezessiv vererbt werden, während die häufigste Form, der G6PD-Mangel, X-chromosomal vererbt wird.

Prenatal diagnosis and management of fetal xerocytosis associated with ascites

OBJECTIVES

To discuss the prenatal diagnosis and management of fetal xerocytosis associated with ascites.

CASE REPORT

A 29-year-old woman with hereditary xerocytosis was found to present a fetus with severe ascites on the 20-week scan. Cordocentesis showed mild anemia and blood transfusion was discarded. Ascites worsened and 2 weeks later a new cordocentesis showed lower hematocrit values. Blood transfusion was performed but ascites remained unchanged. Cordocentesis was repeated at 28 weeks and albumin was transfused. Fetal hemoglobin was within the normal range. Peak systolic velocity of the middle cerebral artery remained normal and correctly predicted mild anemia. Expectant management was followed. An elective cesarean section was performed at 32 weeks because of breech presentation and preterm labor which did not respond to aggressive tocolysis. A female newborn weighing 2,615 g was delivered and required paracenteses and exchange transfusion. The newborn was discharged at 4 weeks of life and at 2 months of age, the ascites resolved completely.

CONCLUSIONS

The mechanism of development of ascites in fetal xerocytosis remains unanswered. As ascites does not seem to be related to fetal anemia or hypoalbuminemia, does not substantially change after blood transfusion and tends to resolve in late gestation, a conservative management is reasonable if fetal anemia is not severe.

Glutathione synthetase deficiency

Glutathione (GSH), one of the most important antioxidants in the eukaryotic organism, is synthesized in a two-step procedure where the last step is catalysed by the enzyme glutathione synthetase (GSS). GSS deficiency is inherited autosomal recessively, and patients with this disease can be divided into three groups, according to their clinical phenotype. Mildly affected patients have mutations affecting the stability of the enzyme, causing a compensated haemolytic anaemia; moderately affected patients have, in addition, metabolic acidosis; and severely affected patients also develop neurological defects and show increased susceptibility to bacterial infections. Moderately and severely affected patients have mutations that compromise the catalytic properties of the enzyme. 5-Oxoprolinuria appears in all three groups, but is more pronounced in the two latter groups. Today, no cure can be offered these patients; they are given vitamins C and E to boost their antioxidant levels, and bicarbonate to correct metabolic acidosis.

New Strategies in the Treatment of the Thalassemias

In addition to the severe beta thalassemias, hematologists have begun to recognize the more severe forms of alpha thalassemia, namely hemoglobin (Hb) H disease and Hb H/Hb Constant Spring, as well as the beta compound heterozygote, beta thalassemia/HbE. Clinically, variably severe anemia becomes apparent in the first year accompanied by occasionally massive expansion of erythropoiesis. The most anemic patients require regular red blood cell transfusions to avoid death from cardiac failure. However, the inevitable iron accumulation leads to dysfunction, primarily involving the heart, liver, and endocrine system; thus, regularly transfused patients require iron chelation. A major discovery was that allogeneic bone marrow (stem cell) transplantation in severely affected subjects with both alpha and beta thalassemia could result in cure. Current work deals with specific complications, such as iron overload and endocrine, cardiopulmonary, thrombophilic, and osteopenic problems. The thalassemias are likely to benefit in the future from specific gene therapy. There are also important advances in genetic counseling based on results of early fetal diagnosis.

Nonimmune hydrops fetalis due to congenital xerocytosis

Hereditary xerocytosis is a rare hemolytic anemia in which erythrocytes are dehydrated due to a loss of potassium and water through their cell wall membrane. In adults, this condition leads to a mild-to-moderate hemolysis. We report a case of hydrops fetalis secondary to hereditary xerocytosis. Management with intrauterine erythrocyte and albumin transfusions resulted in a favorable postnatal course.

[Congenital xerocytosis]

Hereditary xerocytosis is a genetic disease inherited as an autosomal dominant trait and is a rare cause of hemolytic anemia. It is caused by abnormal erythrocyte membrane permeability: monovalent cation pump activity is increased and the Na/K pump cannot compensate for the K lost. As a consequence, xerocytes dehydrate, becoming rigid and sensitive to metabolic stress and oxidation. Morbility depends on the severity of the hemolytic anemia. Periodic episodes of jaundice are common during mild infections; most patients remain asymptomatic but experience mild-to-moderate hemolytic anemia, which is generally well compensated. The diagnostic clues are a markedly increased flow through the Na/K pump with a decrease in total intracellular cation content and subsequent red cell dehydration. Treatment is based on monitoring for eventual complications and careful observation during infections, which may worsen the anemia. Splenectomy is not useful and for some authors may even be contraindicated. The prognosis is generally very good. We report the case of a patient with episodes of hemolytic anemia during intercurrent infections and positive diagnostic tests for hereditary xerocytosis.

The hereditary stomatocytoses: genetic disorders of the red cell membrane permeability to monovalent cations

The hereditary stomatocytoses are mostly accounted for by genetic disorders of red cell membrane permeability to monovalent cations. These conditions, all very rare, are comprised of a hemolytic anemia, frequently macrocytosis, and the presence of abnormally shaped red blood cells. The key test for diagnosis is osmotic gradient ektacytometry, which measures the osmotic resistance and hydration of the red blood cell; the curve depicting the temperature dependence of the cation leak is also important. Syndromes include familial pseudohyperkalemia (FP), which is devoid of hematological features, dehydrated hereditary stomatocytosis (DHS), and overhydrated hereditary stomatocytosis (OHS). Some forms of DHS may be a pleiotropic, showing pseudohyperkalemia and/or perinatal edema. Perinatal edema, if not properly treated, may be lethal but may also resolve spontaneously prior to or shortly after birth and never reappear. Hereditary cryohydrocytosis, type 1 (CHC 1) is characterized by a dramatic resumption of the leak in vitro as the temperature approaches 0 degrees C; cell hydration seems unaltered. In OHS, stomatin, a membrane protein, is sharply reduced; however, this is a secondary event and the primarily mutated protein remains unknown. Hereditary cryohydrocytosis, type 2 (CHC 2) presents similar to OHS, except that the leak dramatically increases close to 0 degrees C. In addition, hematological manifestations are associated with neurological disorders. Of critical practical importance is that splenectomy in DHS or OHS causes thromboembolic events that may be fatal. The genes involved in hereditary stomatocytoses have yet to be identified. Apart from the 16q24-qter locus, related to subsets of DHS and FP, and a chromosome 2 locus assigned to a single case of FP, gene mapping has been difficult. The eventual discovery of individual genes will clarify complicated classification of the stomatocytoses, now based solely on phenotype.

Differential diagnosis and management of anemia in the newborn

Neonatal anemia is a condition with a diverse etiologic spectrum.Therefore, in order to form a focused differential diagnosis, it is important for the caregiver to have some knowledge of the more common causes of low hemoglobin and hematocrit concentrations in the neonate. Proper history taking, physical examination, and interpretation of diagnostic tests can narrow this focus and aid in establishing an accurate diagnosis and in directing the appropriate therapeutic interventions.

[Autoimmune hemolytic anemia with complement-positive direct antiglobulin test]

Autoimmune hemolytic anemia (AIHI) is an infrequent disease in the pediatric age group. Its diagnosis is given by the direct antiglobulin test (DAT) or Coombs' test, which determines which type of globulin (IgG or complement) is the cause of the hemolysis. The type of globulin involved determines the etiology of AIHI, which is usually confirmed by positive results of other laboratory investigations such as cold agglutinin determination or the Donath-Landsteiner test. We present three cases of AIHI. DAT was positive to complement with diverse etiology: warm antibody with IgG-negative DAT, cold agglutinins associated with infectious mononucleosis, and Doth-Landsteiner antibodies. In all patients, empirical treatment with corticosteroids was initiated. The treatment was withdrawn or continued, depending on the final etiology of AIHI.

Red blood cell membrane defects

We present an overview of the currently known molecular basis of red cell membrane disorders. A detailed discussion of the structure of the red cell membrane and the pathophysiology and clinical aspects of its disorders is reported. Generally speaking, hereditary spherocytosis (HS) results from a loss of erythrocyte surface area. The mutations of most cases of HS are located in the following genes: ANK1, SPTB, SLC4A1, EPB42 and SPTA1, which encode for ankyrin, spectrin beta-chain, the anion exchanger 1 (band 3), protein 4.2 and spectrin alpha-chain, respectively. Hereditary elliptocytosis (HE) reflects a diminished elasticity of the skeleton. Its aggravated form, hereditary pyropoikilocytosis (HPP), implies that the skeleton undergoes further destabilization. The mutations responsible for HE and HPP, lie in the SPTA1 and SPTB gene, and in the EPB41 gene encoding protein 4.1. Allele alpha LELY is a common polymorphic allele, which plays the role of an aggravating factor when it occurs in trans of an elliptocytogenic allele of the SPTA1 gene. Southeast Asian ovalocytosis derives from a change in band 3. The genetic disorders of membrane permeability to monovalent cations required a positional cloning approach. In this respect, channelopathies represent a new frontier in the field. Dehydrated hereditary stomatocytosis (DHS) was shown to belong to a pleiotropic syndrome: DHS + fetal edema + pseudohyperkalemia, which maps 16q23-24. Splenectomy is strictly contraindicated in DHS and another disease of the same class, overhydrated hereditary stomatocytosis, because it increases the risk of thromboembolic accidents.

The utility of the autohaemolysis test for children with congenital haemolytic anaemia

Autohaemolysis testing can assist the evaluation of haemolytic anaemia, but involves a cumbersome assay that is difficult to perform accurately. Because this test persists in clinical practice without clear indications or guidelines, we retrospectively reviewed our experience with autohaemolysis testing for children with suspected congenital haemolytic anaemia. Over 12 years, autohaemolysis without glucose was elevated for 38 of 39 children with congenital spherocytosis, while glucose corrected or reduced autohaemolysis in 33 of these patients. Autohaemolysis was elevated only once among seven other cases (four with congenital nonspherocytic haemolytic anaemia and three normal siblings). In three cases of congenital spherocytosis with equivocal osmotic fragility, autohaemolysis was abnormal and corrected with glucose in two. In our experience, autohaemolysis testing was helpful diagnostically in only two of 54 cases, so has only limited utility as a routine test for children with suspected congenital haemolytic anaemia.

Frequency of glucose 6 phosphate dehydrogenase deficiency and related hemolytic anemia in Riyadh, Saudi Arabia

BACKGROUND

Glucose 6 Phosphate dehydrogenase deficiency is present in over 400 million people world wide. It is more common iin tropical and subtropical countries and is one of the important causes of hemolytic anemia and neonatal jaundice. We studied the frequency of glucose-6-phosphate dehydrogenase deficiency and associated complications in Central Region (Riyadh) of Saudi Arabia.

METHODS

A total of 1740 subjects referred by Ministry of Interior and different hospitals in Riyadh were investigated for glucose-6-phosphate dehydrogenase deficiency. Glucose 6 phosphate dehydrogenase activity was determined by a screening test described by Beutler.

RESULTS

Out of these, 106 (6.09%) subjects were deficient. The subjects were divided into marriage and hospital groups. In marriage group deficiency was 4.1% while in hospital group it was 13.3%. In 54 glucose-6-phosphate dehydrogenase deficient patients red blood cell count and haemoglobin levels were determined to see the degree of anaemia. Sixty one percent (61%) had anaemia. In hospital patients 8% patients had severe anaemia while in marriage group no patients had severe anaemia. However mild anaemia was seen in 25% subjects in marriage group.

CONCLUSIONS

In conclusion the study indicates that glucose-6-phosphate dehydrogenase deficiency is common in the central region of Saudi Arabia and a lot of patients present with haemolytic episodes. The haemolytic crisis however is not related to the intake of fava beans. The type of variant causing anaemia and suggestions for prevention in marriage group are outlined.

[Acute lymphoblastic leukemia in a patient with congenital hemolytic anemia: case report]

The authors present a case of a 13-year-old girl with a history of congenital hemolytic anemia (spherocytosis) who developed acute lymphoblastic leukaemia. She received treatment according to the ALL-BFM 91 protocol standard risk group. During maintenance therapy an aplastic crisis caused by Parvovirus B 19 infection had developed. Chemotherapy was stopped in September 1999, and the patient remained in complete remission. In January, 2000 the patient presented with jaundice, caused by a stone in the ductus choledochus. Cholecystectomy and splenectomy were performed, and the the girl became symptomfree. The authors review the most frequent complications of congenital hemolytic anemias (aplastic crisis, haemolytic crisis and cholelithiasis). The occurrence of acute lymphoblastic leukaemia in a patient with congenital hemolytic anemia has not been previously reported.