Favism: clinical and biochemical data

Monogenic Disorders of ROS Production and the Primary Anti-Oxidative Defense

Oxidative stress, characterized by an imbalance between the production of reactive oxygen species (ROS) and the cellular anti-oxidant defense mechanisms, plays a critical role in the pathogenesis of various human diseases. Redox metabolism, comprising a network of enzymes and genes, serves as a crucial regulator of ROS levels and maintains cellular homeostasis. This review provides an overview of the most important human genes encoding for proteins involved in ROS generation, ROS detoxification, and production of reduced nicotinamide adenine dinucleotide phosphate (NADPH), and the genetic disorders that lead to dysregulation of these vital processes. Insights gained from studies on inherited monogenic metabolic diseases provide valuable basic understanding of redox metabolism and signaling, and they also help to unravel the underlying pathomechanisms that contribute to prevalent chronic disorders like cardiovascular disease, neurodegeneration, and cancer.

Dynamics of G6PD activity in patients receiving weekly primaquine for therapy of Plasmodium vivax malaria

BACKGROUND

Acute Plasmodium vivax malaria is associated with haemolysis, bone marrow suppression, reticulocytopenia, and post-treatment reticulocytosis leading to haemoglobin recovery. Little is known how malaria affects glucose-6-phosphate dehydrogenase (G6PD) activity and whether changes in activity when patients present may lead qualitative tests, like the fluorescent spot test (FST), to misdiagnose G6PD deficient (G6PDd) patients as G6PD normal (G6PDn). Giving primaquine or tafenoquine to such patients could result in severe haemolysis.

METHODS

We investigated the G6PD genotype, G6PD enzyme activity over time and the baseline FST phenotype in Cambodians with acute P. vivax malaria treated with 3-day dihydroartemisinin piperaquine and weekly primaquine, 0·75 mg/kg x8 doses.

RESULTS

Of 75 recruited patients (males 63), aged 5-63 years (median 24), 15 were G6PDd males (14 Viangchan, 1 Canton), 3 were G6PD Viangchan heterozygous females, and 57 were G6PDn; 6 patients had α/β-thalassaemia and 26 had HbE. Median (range) Day0 G6PD activities were 0·85 U/g Hb (0·10-1·36) and 11·4 U/g Hb (6·67-16·78) in G6PDd and G6PDn patients, respectively, rising significantly to 1·45 (0·36-5·54, p<0.01) and 12·0 (8·1-17·4, p = 0.04) U/g Hb on Day7, then falling to ~Day0 values by Day56. Day0 G6PD activity did not correlate (p = 0.28) with the Day0 reticulocyte counts but both correlated over time. The FST diagnosed correctly 17/18 G6PDd patients, misclassifying one heterozygous female as G6PDn.

CONCLUSIONS

In Cambodia, acute P. vivax malaria did not elevate G6PD activities in our small sample of G6PDd patients to levels that would result in a false normal qualitative test. Low G6PDd enzyme activity at disease presentation increases upon parasite clearance, parallel to reticulocytosis. More work is needed in G6PDd heterozygous females to ascertain the effect of P. vivax on their G6PD activities.

TRIAL REGISTRATION

The trial was registered (ACTRN12613000003774) with the Australia New Zealand Clinical trials (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=363399&isReview=true).

Clinical Manifestations and Therapeutic Findings of the Children with Glucose-6-Phosphate Dehydrogenase Deficiency Presenting Favism

AIM

Favism is characterized as acute anemia, due to Glucose-6-phosphate dehydrogenase (G6PD) deficiency as a result of fava beans intake. It is associated with paleness, jaundice, and hemoglobinuria. In this study, signs, symptoms and therapeutic findings of the patients with hemolysis due to G6PD deficiency were investigated in Shahid Madani Hospital of Khorramabad, Lorestan.

METHODS

This is a single-center cross-sectional descriptive study that was conducted on all children with G6PD deficiency-induced hemolysis.

RESULTS

308 children (64.3% male and 35.7% female) were included in this study. The most common complaint was jaundice (82.5%) and the most common cause of hemolysis was the intake of fava bean (85.7%). 68% of the children were treated with hydration/fluid therapy. Blood transfusion was conducted in 36.36% of the cases and the mean of blood administered was 18.9 cc/kg.

CONCLUSION

In this study, hydration therapy was performed in most of the children presenting favism. Also, the incorrect calculation of the amount of blood needed for transfusion increased the frequency of blood transfusions and prolonged hospitalization time.

Pattern of Hemolytic Anemia Among Egyptian Pediatric Emergency Department Patients

OBJECTIVES

The emergency department is considered the backbone of the medical service offered in any hospital. Yet, the data on the frequency of pediatric hematological presentation is scanty. Anemia occurs in 9% to 14% of pediatric emergency department (ED) patients. Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects more than 400 million people worldwide. Unfortunately, we do not have screening program for G6PD deficiency in Egypt. The aim of this study is to assess the burden of hemolytic crisis among Egyptian children visiting ED.

METHODS

This is a prospective cross-sectional study among children presenting with acute hemolytic crisis in the ED of New Children Hospital, Cairo University from March to June 2016. Cases underwent full history taking, clinical examination, and laboratory tests based on clinical judgment of the resident. We categorized the presenting hemolytic anemias into 3 groups: G6PD deficiency, acute hemolysis in previously diagnosed patients with chronic hemolytic anemia, and acute undiagnosed hemolytic anemia.

RESULTS

Our study included 143 patients, 109 males (76.22%) and 34 females (23.76%), with a mean age 36 months (range, 3-188 months), who presented with hemolytic anemia in the ED. Seventy-six cases (53.1%) were diagnosed as G6PD deficiency, 36 (25.2%) were diagnosed as chronic hemolytic anemia, and 31 (21.7%) were diagnosed as undiagnosed acute hemolytic anemia.

CONCLUSIONS

Hemolytic anemia is very common presentation in ED. G6PD deficiency is the most common cause, representing 53.1% of the hemolytic anemia.

Primaquine Pharmacokinetics in Lactating Women and Breastfed Infant Exposures

Background

Primaquine is the only drug providing radical cure of Plasmodium vivax malaria. It is not recommended for breastfeeding women as it causes hemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals, and breast milk excretion and thus infant exposure are not known.

Methods

Healthy G6PD-normal breastfeeding women with previous P. vivax infection and their healthy G6PD-normal infants between 28 days and 2 years old were enrolled. Mothers took primaquine 0.5 mg/kg/day for 14 days. Primaquine and carboxyprimaquine concentrations were measured in maternal venous plasma, capillary plasma, and breast milk samples and infant capillary plasma samples taken on days 0, 3, 7, and 13.

Results

In 20 mother-infant pairs, primaquine concentrations were below measurement thresholds in all but 1 infant capillary plasma sample (that contained primaquine 2.6 ng/mL), and carboxyprimaquine was likewise unmeasurable in the majority of infant samples (maximum value 25.8 ng/mL). The estimated primaquine dose received by infants, based on measured breast milk levels, was 2.98 µg/kg/day (ie, ~0.6% of a hypothetical infant daily dose of 0.5 mg/kg). There was no evidence of drug-related hemolysis in the infants. Maternal levels were comparable to levels in nonlactating patients, and adverse events in mothers were mild.

Conclusions

The concentrations of primaquine in breast milk are very low and therefore very unlikely to cause adverse effects in the breastfeeding infant. Primaquine should not be withheld from mothers breastfeeding infants or young children. More information is needed in neonates.

Clinical Trials Registration

NCT01780753.

Red Blood Cell Enzyme Disorders

Mature red blood cells are reliant on the glycolytic pathway for energy production and the hexose monophosphate shunt for cell protection from oxidative insults. The most common red blood cell enzyme disorders are characterized by hemolysis but with wide clinical variability. Glucose-6-phosphate dehydrogenase deficiency is the most common red cell enzyme disorder worldwide. Frequent clinical presentations include neonatal jaundice and episodic hemolysis after exposure to oxidative stress. Symptoms of pyruvate kinase deficiency and other glycolytic enzyme disorders include neonatal jaundice, chronic hemolytic anemia, gallstones, and transfusion-related and transfusion-independent iron overload. Diagnosis is critical for appropriate supportive care, monitoring, and treatment.

Hepatic transcriptional profiling response to fava bean-induced oxidative stress in glucose-6-phosphate dehydrogenase-deficient mice

Favism is an acute hemolytic syndrome caused by the ingestion of fava bean (FB) in glucose 6-phosphate dehydrogenase (G6PD) deficient individuals. However, little is known about the global transcripts alteration in liver tissue after FB ingestion in G6PD-normal and -deficient states. In this study, deep sequencing was used to analyze liver genes expression alterations underlying the effects of FB in C3H (Wild Type, WT) and G6PD-deficient (G6PDx) mice and to evaluate and visualize the collective annotation of a list of genes to Gene Ontology (GO) terms associated with favism. Our results showed that FB resulted in a decrease of glutathione (GSH)-to-oxidized glutathione (GSSG) ratio and an increase of malondialdehyde (MDA) both in the G6PDx and WT-control check (CK) mice plasma. Significantly, liver transcript differences were observed between the control and FB-treated groups of both WT and G6PDx mice. A total of 320 differentially expressed transcripts were identified by comparison of G6PDx-CK with WT-CK and were associated with immune response and oxidation-reduction function. A total of 149 differentially expressed genes were identified by comparison of WT-FB with WT-CK. These genes were associated with immune response, steroid metabolic process, creatine kinase activity, and fatty acid metabolic process. A total of 438 differential genes were identified by comparing G6PDx-FB with G6PD-CK, associated with the negative regulation of fatty acid metabolic process, endoplasmic reticulum, iron binding, and glutathione transferase activity. These findings indicate that G6PD mutations may affect the functional categories such as immune response and oxidation-reduction.

Evaluation of liver and kidney function in favism patients

BACKGROUND

G6PD deficiency is the most common enzymopathy of red blood cells. The clinical symptoms of favism are jaundice, hematuria and haemolytic anaemia that seem to affect liver and kidney in long term. Thus we evaluate kidney and liver function of favism patients in an endemic area of the disease with a high rate of fava beans cultivation.

METHODS

This study was performed on favism patients and healthy controls referring to Iranshahr central hospital. Liver and kidney function tests were performed.

RESULTS

The results showed a statistically significant difference between these two groups (p <0.05) for liver function tests, (AST, ALT and ALP), but not for renal tests (BUN and creatinine) (p >0.05).

CONCLUSION

Due to abnormalities were seen in the liver function tests of these patients, we suggest that these tests be regularly performed for favism patients who are constantly exposed to oxidant agents.

Recent progress and clinical importance on pharmacogenetics in cancer therapy

Recent advances have provided unprecedented opportunities to identify prognostic and predictive markers of efficacy of cancer therapy. Genetic markers can be used to exclude patients who will not benefit from therapy, exclude patients at high risk of severe toxicity and adjust dosing. Genomic approaches for marker discovery now include genome-wide association studies and tumor DNA sequencing. The challenge is now to select markers for which there is enough evidence to transition them to the clinic. The hurdles include the inherent low frequency of many of these markers, the lengthy validation process through trials, as well as legislative and economic hurdles. Attempts to answer questions about certain markers more quickly have led to an increased popularity of trials with enrichment design, especially in light of the dramatic phase I results seen in recent months. Personalized medicine in oncology is a step closer to reality.

Modification to reporting of qualitative fluorescent spot test results improves detection of glucose-6-phosphate dehydrogenase (G6PD)-deficient heterozygote female newborns

INTRODUCTION

The glucose-6-phosphate dehydrogenase (G6PD) fluorescent spot test (FST) is a useful screening test for G6PD deficiency, but is unable to detect heterozygote G6PD-deficient females. We sought to identify whether reporting intermediate fluorescence in addition to absent and bright fluorescence on FST would improve identification of mildly deficient female heterozygotes.

METHODS

A total of 1266 cord blood samples (705 male, 561 female) were screened for G6PD deficiency using FST (in-house method) and a quantitative enzyme assay. Fluorescence intensity of the FST was graded as either absent, intermediate or normal. Samples identified as showing absent or intermediate fluorescence on FST were analysed for the presence of G6PD mutations using TaqMan@SNP genotyping assays and direct nucleotide sequencing.

RESULTS

Of the 1266 samples, 87 samples were found to be intermediate or deficient by FST (49 deficient, 38 intermediate). Of the 49 deficient samples, 48 had G6PD enzyme activity of ≤ 9.5 U/g Hb and one sample had normal enzyme activity. All 38 intermediate samples were from females. Of these, 21 had G6PD activity of between 20% and 60%, and 17 samples showed normal G6PD activity. Twenty-seven of the 38 samples were available for mutation analysis of which 13 had normal G6PD activity. Eleven of the 13 samples with normal G6PD activity had identifiable G6PD mutations.

CONCLUSION

Glucose-6-phosphate dehydrogenase heterozygote females cannot be identified by FST if fluorescence is reported as absent or present. Distinguishing samples with intermediate fluorescence from absent and bright fluorescence improves detection of heterozygote females with mild G6PD deficiency. Mutational studies confirmed that 85% of intermediate samples with normal enzyme activity had identifiable G6PD mutations.

Fatal kernicterus in a girl deficient in glucose-6-phosphate dehydrogenase: a paradigm of synergistic heterozygosity

A 6-day-old female newborn, readmitted for extreme hyperbilirubinemia with bilirubin encephalopathy, died despite 2 double-volume exchange transfusions. On autopsy examination the basal ganglia and hippocampus were selectively stained deep yellow. The infant was heterozygous for both the glucose-6-phosphate dehydrogenase Mediterranean mutation and for the (TA)(6)/(TA)(7) promoter polymorphism for the gene encoding the bilirubin conjugating enzyme uridine diphosphate-glucuronosyltransferase 1A1 (UGT1A1*28, associated with Gilbert syndrome). No additional mutations of the UGT1A1 were detected. Seemingly innocuous, heterozygotic mutations may interact synergistically to result in serious and even fatal outcomes.

Glucose-6-phosphate dehydrogenase deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect, being present in more than 400 million people worldwide. The global distribution of this disorder is remarkably similar to that of malaria, lending support to the so-called malaria protection hypothesis. G6PD deficiency is an X-linked, hereditary genetic defect due to mutations in the G6PD gene, which cause functional variants with many biochemical and clinical phenotypes. About 140 mutations have been described: most are single base changes, leading to aminoacid substitutions. The most frequent clinical manifestations of G6PD deficiency are neonatal jaundice, and acute haemolytic anaemia, which is usually triggered by an exogenous agent. Some G6PD variants cause chronic haemolysis, leading to congenital non-spherocytic haemolytic anaemia. The most effective management of G6PD deficiency is to prevent haemolysis by avoiding oxidative stress. Screening programmes for the disorder are undertaken, depending on the prevalence of G6PD deficiency in a particular community.

Glucose-6-phosphate dehydrogenase variants associated with favism in Thai children

In a study conducted at Songklanagarind Hospital in the south of Thailand, the subjects were 225 patients (210 boys and 15 girls) with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Favism was found in 3.6% of the G6PD-deficient children. Approximately one half of the G6PD-deficient patients with favism were younger than 2 years. Sudden onset of anemia was found within 1 to 3 days after ingestion of dried fava beans. The classic features of favism, which are pallor, hemoglobinuria, and jaundice, were detected in all cases. To characterize the known G6PD mutations in Thai children, molecular analysis was performed for 8 G6PD-deficient children with favism by a combination of polymerase chain reaction-restriction fragment length polymorphism analysis and amplification refractory mutation system analysis. The G6PD variants in these children were G6PD Kaiping 1388,G-->A; G6PD Mahidol 487,G-->A; G6PD Viangchan 871,G-->A; and uncharacterized mutation with silent mutation 1311,C-->T.

Acute hemolysis and severe neonatal hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient heterozygotes

Two premature female infants had severe hyperbilirubinemia caused by hemolysis. Both neonates were heterozygotes for the glucose-6-phosphate dehydrogenase Mediterranean mutation as determined by DNA analysis. Glucose-6-phosphate dehydrogenase-deficient heterozygotes may be susceptible to the complications of this enzyme deficiency.

Neonatal hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient heterozygotes

OBJECTIVES

We assessed the incidence of hyperbilirubinemia, defined as serum total bilirubin >/=15 mg/dL (256 micromol/L), in a cohort of Sephardic Jewish female neonates at risk for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency with especial emphasis on the heterozygotes. We studied the roles of hemolysis by blood carboxyhemoglobin (COHb) determinations and of the variant promoter of the gene for the bilirubin-conjugating enzyme uridine 5'-diphosphate glucuronosyltransferase 1 (UGT1A1) seen in Gilbert's syndrome in the pathogenesis of the hyperbilirubinemia.

METHODS

Consecutively born, healthy, term, female neonates were screened for G-6-PD deficiency and observed clinically with serum bilirubin evaluations as indicated for hyperbilirubinemia. On day 3, blood was sampled for COHb, total hemoglobin (tHb), and a mandatory serum bilirubin determination. COHb, determined by gas chromatography, was expressed as percentage of tHb and corrected for inspired carbon monoxide (COHbc). DNA was analyzed for the G-6-PD Mediterranean563T mutation and for the variant UGT1A1 gene.

RESULTS

The cohort included 54 G-6-PD-deficient heterozygotes, 19 deficient homozygotes, and 112 normal homozygotes. More heterozygotes (12/54, 22%; relative risk: 2.26; 95% CI: 1.07-4.80) and deficient homozygotes (5/19, 26.3%; relative risk: 2.68; 95% CI: 1.05-6.90) developed hyperbilirubinemia, than did normal homozygotes (11/112, 9.8%). Third-day serum bilirubin values that were obtained from 144 neonates were significantly higher in both heterozygotes (11.2 +/- 3. 7 mg/dL [192 +/- 64 micromol/L]) and G-6-PD-deficient homozygotes (12.0 +/- 3.0 mg/dL [206 +/- 52 micromol/L]) than in the G-6-PD normal homozygotes (9.4 +/- 3.4 mg/dL [160 +/- 58 micromol/L). In contrast, COHbc values were higher only in G-6-PD-deficient homozygotes (0.74% +/- 0.14%) and not in heterozygotes (0.69% +/- 0. 19%, not statistically significant), compared with control values (0. 63% +/- 0.19%). High COHbc values were not a prerequisite for the development of hyperbilirubinemia in any of the G-6-PD genotypes. A greater incidence of hyperbilirubinemia was found among the G-6-PD-deficient heterozygotes, who also had the variant UGT1A1 gene, in both heterozygous (6/20, 30%) and homozygous (4/8, 50%) forms, than was found in their counterparts with the normal UGT1A1 gene (2/26, 7.7%). This effect was not seen in the G-6-PD normal homozygote group. A color reduction screening test for G-6-PD deficiency identified only 20.4% (11/54) of the heterozygotes.

CONCLUSIONS

We showed that G-6-PD-deficient heterozygotes, categorically defined by DNA analysis, are at increased risk for neonatal hyperbilirubinemia. The screening test that was used was unable to detect most heterozygotes. Increased bilirubin production was not crucial to the development of hyperbilirubinemia, but presence of the variant UGT1A1 gene did confer increased risk.

Severe neonatal jaundice associated with glucose-6-phosphate dehydrogenase deficiency: pathogenesis and global epidemiology

The association of glucose-6-phosphate dehydrogenase deficiency (G6PD def) with severe neonatal jaundice (NJ) and Kernicterus was described just over 30 years ago in reports from Sardinia (1-4) Singapore (5,6) and Greece (7,8). In this review we will examine the progress made since that time in our understanding of the pathophysiology of severe NJ associated with G6PD def, its global epidemiology, and its role in the balanced polymorphism of the G6PD def gene (Gd). Including this review in the Festschrift to Spyros Doxiadis should highlight his contribution to the field. In Greece the search for a new cause of severe NJ and Kernicterus was triggered by his realization that the recognized at the time, causes of severe NJ were absent in a large proportion of the neonates treated at the "Alexandra" Maternity Hospital in Athens (9).

Variants of glucose-6-phosphate dehydrogenase are due to missense mutations spread throughout the coding region of the gene

Glucose-6-phosphate dehydrogenase (G6PD) is remarkable for its genetic diversity in humans. Many variants of G6PD have been described with wide ranging levels of enzyme activity and associated clinical symptoms. Fifty-eight different mutations have now been identified and these account for 97 named G6PD variants. The mutations are almost exclusively missense mutations, causing single amino acid substitutions. They are spread throughout the coding region of the gene, although there appears to be a cluster of mutations that cause a more severe clinical phenotype towards the 3' end of the gene. The absence of large deletions, frameshift mutations and nonsense mutations is consistent with the notion that a total lack of G6PD activity would be lethal.

Screening for glucose-6-phosphate dehydrogenase deficiency as a preventive measure: prevalence among 1,286,000 Greek newborn infants

We evaluated the Greek screening program for glucose-6-phosphate dehydrogenase (G6PD) deficiency, which was incorporated into the existing national phenyketonuria (PKU) screening program to identify infants with G6PD deficiency and eliminate the induction of acute hemolytic crisis by informing the families about the extrinsic factors that G6PD-deficient patients should avoid. Between 1977 and 1989, 1,286,000 infants were screened. The fluorescent spot test was used on samples extracted from dried blood spots. Abnormal fluorescence due to G6PD deficiency (severe or partial) was found in 3.14% of the samples (1 in 22 males and 1 in 54 females). The sensitivity of the test for homozygosity and hemizygosity was 100%. In heterozygosity the test identifies only subjects who have considerably diminished enzyme activity. The test is inexpensive when added to the PKU screening program ($0.90 US per test). We believe that screening a population for G6PD deficiency is justified if the incidence of the deficiency in the population is high and the clinical manifestations serious. The fluorescent spot test is recommended because it is reliable, easy to perform, and inexpensive. The test must be performed within a fortnight from sampling, and the cards must not be exposed to high temperature or humidity.

Red-cell GSH regeneration and glutathione reductase activity in G6PD variants in the Ferrara area

Red-cell studies were carried out on three groups of G6PD-deficient subjects with different G6PD variants from the Ferrara area of Northern Italy. Red-cell GSH and activities of G6PD, glutathione reductase (GR), glutathione peroxidase (GPx) and superoxide dismutase (SOD) were measured. A method was developed to measure red-cell GSH regeneration after oxidation of endogenous GSH in whole blood by diamide and only this clearly distinguished the variants from each other and from normal. Regeneration by 1 h was lowest in the Mediterranean variant, 0-10.2% in contrast to 93-98% in normal. A predisposition to a haemolytic crisis after ingestion of fava beans was not clearcut, but subjects appeared to be at risk if GSH regeneration at 1 h was less than 30% of the endogenous level, and red-cell FAD+ was very high indicated by high in vitro GR activity and inhibition by added FAD+. It is suggested that the most informative tests in G6PD deficiency are measurements of GSH regeneration in intact red cells plus GR activity and/or red-cell flavin compounds.

Glucose 6-Phosphate dehydrogenase deficiency genetic, pathophysiological and therapeutic aspects

Glucose 6-phosphate dehydrogenase (G6PD) is the first enzyme of the pentose phosphate pathway. It exists in over 250 variants which are divided broadly into five classes on the basis of residual enzyme activity and clinical manifestations. The variants with reduced activity result in G6PD deficiency. This is inherited as an X-linked recessive disorder and occurs at a much higher frequency in the male than in the female. Most G6PD deficient individuals show no clinical abnormality under normal conditions, but acute hemolytic crisis may occur. Several nonhemolytic abnormalities occur as well in G6PD deficients at a higher frequency than in nondeficients. Several nonhemolytic abnormalities occur as well in G6PD deficients at a higher frequency than in nondeficients. The genetic, pathophysiologic, and therapeutic aspects of G6PD deficiency are presented; and the possibility of genetic counselling, care in blood banks, and benefits of education the G6PD deficients are discussed.

Favism: looking for an autosomal gene associated with glucose-6-phosphate dehydrogenase deficiency

Favism is a severe, acute haemolytic anaemia which occurs in about 20% of G6PD deficient subjects after ingestion of fava beans. Since not all G6PD deficient subjects are sensitive to fava beans, the possibility has been suggested that extra erythrocytic factors may play an important role in the susceptibility to haemolytic favism. To test the hypothesis that an autosomal enzyme is involved in the pathogenesis of favism, we carried out a beta-glucosidase assay in small intestine biopsies from normal subjects and G6PD deficient subjects with or without favism. Beta-glucosidase might be involved in the absorption and metabolism of fava beans and a quantitative polymorphism could explain the different susceptibility to fava beans of G6PD deficient subjects. Our observation showed no consistent quantitative polymorphism of beta-glucosidase in the subjects examined.

Biological activities of broad bean (Vicia faba L.) extracts cultivated in South Anatolia in favism sensitive subjects

Aqueous extracts of a different variety of fresh broad bean seeds obtained from a favism endemic area in Turkey, were incubated with blood from sensitive and non-sensitive (control) subjects. Red blood cells were characterized by a whole blood glutathione (GSH) and a deficiency of Glucose-6-phosphate dehydrogenase (G-6-PD) activity. As the decrease in GSH percent is taken as an index of haemolytic activity, the test results were as following: Sakiz , Milas -Region, French broad bean extracts reduced the blood GSH levels 48%, 70%, 46% and 53%, respectively, in favism sensitive subjects. Active principles which are responsible for the haemolysis ( Vicine and Convicine ) were isolated from broad beans and their effects on GSH levels of blood were 99% and 81%, respectively, in favism sensitive subjects and 33.3% and 19% in normal subjects.

Combined erythrocyte glucosephosphate isomerase (GPI) and glucose-6-phosphate dehydrogenase (G6PD) deficiency in an Italian family

A severe hemolytic crisis was observed in a 5-year-old boy of Italian origin. Analysis of his hemolysate revealed a hemizygous deficiency of glucose-6-phosphate dehydrogenase (G6PD) and a heterozygous deficiency of glucosephosphate isomerase (GPI). According to the literature this is the fourth family with a combined deficiency of these two enzymes located on different chromosomes. Only the G6PD deficiency seems to be responsible for the hemolytic crisis.

Favism: erythrocyte metabolism during haemolysis and reticulocytosis

The reduced activity of glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate; NADP+ 1-oxidoreductase; G6PF) in Mediterranean erythrocytes explains the precarious equilibrium of the hexose monophosphate pathway (HMP) and the susceptibility of these cells to haemolytic agents. G6PD-deficient erythrocytes, in steady-state conditions, have a low NADPH/NADP+ ratio, thus allowing the HMP to operate at its maximal intracellular rate and to compensate the intrinsic erythrocyte enzyme deficiency. Studies started soon after accidental intake of fava beans by sensitive G6PD-deficient subjects demonstrate a decrease of both NADPH/NADP+ ratio and reduced glutathione. The metabolic effects induced by fava beans may be attributed to oxidative stress probably associated with an inhibitor effect of some unknown metabolite on the HMP. The availability of erythrocytes from subjects recovering from haemolysis with high reticulocyte counts and increased G6PD activity, provides new information on the rate of synthesis as well as on the in vivo decay of the mutant enzyme. Correlation of G6PD activity to reticulocyte count and extrapolation to an ideally homogenous population of reticulocytes reveal that the mutant enzyme is synthesized at a nearly normal rate. Furthermore, the present correlation allows an estimate of the in vivo half-life of Mediterranean G6PD. The rate of decline of about 8 d observed in this study well correlates to the intracellular metabolic aspects of G6PD Mediterranean erythrocytes.

Jaundice and bilirubin levels in Greek children with favism

Jaundice and bilirubin levels varied widely in 85 children with favism. Low bilirubin levels (less than 2 mg/100 ml) with clinically undetectable jaundice were seen in 34 (40%), mild jaundice in 32 (38%), moderate in 16 (19%), and severe (greater than 8 mg/100 ml) in 3 (4%). Bilirubin levels were unrelated to the severity of anaemia or to reticulocytosis. The absence of bilirubinaemia and jaundice in a high proportion of the patients was attributed to the ability of the liver to conjugate large amounts of bilirubin. The extreme bilirubinaemia and jaundice observed in a minority of cases was attributed to the existence of an additional hereditary factor affecting the liver.

Red cell enzymes

As compared to other cells of the body, the mammalian red cell has one of the simplest structural organizations. As a result, this cell has been extensively used in studies involving the structure, function, and integrity of cell membranes as well as cytoplasmic events. Additionally, the metabolic activities of the red blood cell are also relatively simple. During the past quarter century or so, an ocean of knowledge has been gathered on various aspects of red cell metabolism and function. The fields of enzymes, hemoglobin, membrane, and metabolic products comprise the major portion of this knowledge. These advances have made valuable contributions to biochemistry and medicine. Despite these favorable aspects of this simple, anucleated cell, it must be conceded that our knowledge about the red cell is far from complete. We are still in the dark concerning the mechanism involved in several aspects of its membrane, hemoglobin, enzymes, and a large number of other constituents. For example, a large number of enzymes with known catalytic activity but with unknown function have eluded investigators despite active pursuit. This review will be a consolidation of our present knowledge of human red cell enzymes, with particular reference to their usefulness in the diagnosis and therapy of disease. Owing to the multitude of publications by prominent investigators on each of the approximately 50 enzymes discussed in this review, it was impossible to cite a majority of them.

The epidemiology of favism

Favism is a potential obstacle to the use of the fava bean in the development of a locally produced, inexpensive weaning food for the Middle East and North Africa. The purposes of this study were to define the epidemiology of favism, to evaluate the advisability of using the fava bean in a weaning food, and to suggest ways of avoiding or eliminating the toxic factor in the bean. Field observations, locally acquired data, and a literature review suggested that the use of the fava bean in a weaning food would be hazardous, but that the hazard might be overcome by using certain strains of the bean or, more particularly, by using old dried beans. The disease is usually directly related in time to the harvesting and availability of fresh beans, but it is also associated with fresh dried beans. On the basis of the age distribution of the disease, patterns of bean consumption, and local food taboos it appears that the toxic factor is concentrated in the skin of the bean, that it is heat-stable, that in dried beans it decreases with age, and that it crosses into the breast milk of lactating mothers. It also appears that disease expression may be a result of the interaction of several host factors, such as nutritional status and the consumption of other foods. These observations are consistent with the results of laboratory studies, which incriminate vicine, divicine, and DOPA in the etiology of favism.