Frequency of glucose-6-phosphate dehydrogenase (G6PD) mutations in Chinese, Filipinos, and Laotians from Hawaii

Glucose-6-phosphate dehydrogenase deficiency and neonatal indirect hyperbilirubinemia: a retrospective cohort study among 40,305 consecutively born babies

BACKGROUND AND OBJECTIVE

Glucose-6-phosphate dehydrogenase deficiency (G6PDD) being highly prevalent in the Middle East, the primary objective was to estimate the incidence of neonatal jaundice among G6PD-deficient neonates and to explore its association with various risk factors.

METHODS

This retrospective cohort study includes 7 years data of neonates diagnosed with G6PDD between 1st January 2015, and 30 September 2022, from Al Wakra Hospital, HMC Qatar.

RESULTS

Among the 40,305 total births, 1013 had G6PDD with an incidence of 2.51%. Of all the G6PDD babies, 24.6% (249/1013) received phototherapy and three babies required exchange transfusion. Statistically significant associations were noted between the need for phototherapy and gestational age, gestational age groups, birth weight, and birth weight groups, but logistic regression analysis showed significant association for phototherapy only with the gestational age group.

CONCLUSION

Universal screening and proper follow-up is essential for G6PDD as it plays crucial role in neonatal jaundice.

Glucose-6-phosphate dehydrogenase deficiency as a cause for nonimmune hydrops fetalis and severe fetal anemia: A systematic review

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked recessive disorder that predisposes individuals to hemolysis due to an inborn error of metabolism. We performed a systematic literature review to evaluate G6PD deficiency as a possible etiology of nonimmune hydrops fetalis (NIHF) and severe fetal anemia.

METHODS

PubMed, OVID Medline, Scopus, and clinicaltrials.gov were queried from inception until 31 April 2023 for all published cases of NIHF and severe fetal anemia caused by G6PD deficiency. Keywords included "fetal edema," "hydrops fetalis," "glucose 6 phosphate dehydrogenase deficiency," and "fetal anemia." Cases with workup presuming G6PD deficiency as an etiology for NIHF and severe fetal anemia were included. PRISMA guidelines were followed.

RESULTS

Five cases of G6PD-related NIHF and one case of severe fetal anemia were identified. Four fetuses (4/6, 66.7%) were male and two fetuses (2/6, 33.3%) were female. Mean gestational age at diagnosis of NIHF/anemia and delivery was 32.2 ± 4.9 and 35.7 ± 2.4 weeks, respectively. Four cases (66.7%) required a cordocentesis for fetal transfusion, and two cases (33.3%) received blood transfusions immediately following delivery. Among the four multigravida cases, two (50%) noted previous pregnancies complicated by neonatal anemia. When reported, the maternal cases included two G6PD deficiency carrier patients and two G6PD-deficient patients. Exposures to substances known to cause G6PD deficiency-related hemolysis occurred in 3/6 (50%) cases.

CONCLUSION

Six cases of NIHF/severe fetal anemia were associated with G6PD deficiency. While G6PD deficiency is an X-linked recessive condition, female fetuses can be affected. Fetal G6PD deficiency testing can be considered if parental history indicates, particularly if the standard workup for NIHF is negative.

Distribution of G6PD deficiency genotypes among Southeast Asian populations

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a group of X-linked, hereditary genetic disorders caused by mutations in the G6PD gene and results in functional variants of about 400 biochemical and clinical phenotypes. Among them, more than 215 genotypes have been identified so far. In this review, specific features of the genotype distribution in different communities and countries are discussed based on multiple reports and our molecular epidemiological studies of Southeast Asian countries. Particularly, in Indonesia, the frequency distribution of G6PD deficiency variants was distinct between western and eastern Indonesian populations, suggesting two different gene flows during Indonesian expansions.

Molecular Characterization of Glucose-6-Phosphate Dehydrogenase Deficiency in the Shenzhen Population

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is caused by one or more mutations in the G6PD gene on chromosome X. This study aimed to characterize the G6PD gene variant distribution in Shenzhen of Guangdong province.

METHODS

A total of 33,562 individuals were selected at the hospital for retrospective analysis, of which 1,213 cases with enzymatic activity-confirmed G6PD deficiency were screened for G6PD gene variants. Amplification refractory mutation system PCR was first used to screen the 6 dominant mutants in the Chinese population (c.1376G>T, c.1388G>A, c.95A>G, c.1024C>T, c.392G>T, and c.871G>A). If the 6 hotspot variants were not found, next-generation sequencing was then performed. Finally, Sanger sequencing was used to verify all the mutations.

RESULTS

The incidence of G6PD deficiency in this study was 3.54%. A total of 26 kinds of mutants were found in the coding region, except for c.-8-624T>C, which was in the noncoding region. c.1376G>T and c.1388G>A, both located in exon 12, were the top 2 mutants, accounting for 68.43% of all individuals. The 6 hotspot mutations had a cumulative proportion of 94.02%.

CONCLUSIONS

This study provided detailed characteristics of G6PD gene variants in Shenzhen, and the results would be valuable to enrich the knowledge of G6PD deficiency.

Glucose-6-Phosphate Dehydrogenase Deficiency-Associated Hemolytic Anemia and Methemoglobinemia in a Patient Treated With Hydroxychloroquine in the Era of COVID-19

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymatic disorder of red blood cells worldwide. The severity of hemolytic anemia varies among individuals with G6PD deficiency, depending on the genetic variant in the G6PD gene; this makes the diagnosis of the condition more challenging in some cases. In this report, we present a case of severe hemolytic anemia and methemoglobinemia in a patient with G6PD deficiency who had been exposed to hydroxychloroquine prescribed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. To the best of our knowledge and based on a literature search, this is one of the first case reports in the literature about hemolytic crisis and methemoglobinemia in a patient with critical illness due to severe coronavirus disease 2019 (COVID-19) who was exposed to hydroxychloroquine. It is critical for physicians and caregivers to recognize the effects of oxidative stressors such as hydroxychloroquine, particularly in this era of the COVID-19 pandemic and in regions with a high prevalence of G6PD deficiency, for the appropriate management of this unique subset of patients.

Molecular characterization of G6PD mutations reveals the high frequency of G6PD Aures in the Lao Theung population

Background

The prevalence and genotypes of G6PD deficiency vary worldwide, with higher prevalence in malaria endemic areas. The first-time assessment of G6PD deficiency prevalence and molecular characterization of G6PD mutations in the Lao Theung population were performed in this study.

Methods

A total of 252 unrelated Lao Theung participants residing in the Lao People’s Democratic Republic (PDR) were recruited. All participant samples were tested for G6PD enzyme activity and G6PD gene mutations. The amplification refractory mutation system (ARMS)-PCR for detecting G6PD Aures was developed.

Results

The G6PD mutations were detected in 11.51% (29/252) of the participants. Eight G6PD mutations were detected. The G6PD Aures was the most common mutation identified in this cohort, which represented 58.62% (17/29) of all mutation. The mutation pattern was homogenous, predominantly involving the G6PD Aures mutation (6.75%), followed by 1.19% G6PD Union and 0.79% each G6PD Jammu, G6PD Mahidol and G6PD Kaiping. One subject (0.4%) each carried G6PD Viangchan and G6PD Canton. Interestingly, one case of coinheritance of G6PD Aures and Quing Yan was detected in this cohort. Based on levels of G6PD enzyme activity, the prevalence of G6PD deficiency in the Lao Theung population was 9.13% (23/252). The prevalence of G6PD deficient males and females (activity < 30%) in the Lao Theung population was 6.41% (5/78) and 1.72% (3/174), respectively, and the prevalence of G6PD intermediate (activity 30–70%) was 5.95% (15/252).

Conclusions

The G6PD Aures mutation is highly prevalent in the Lao Theung ethnic group. The common G6PD variants in continental Southeast Asian populations, G6PD Viangchan, Canton, Kaiping, Union and Mahidol, were not prevalent in this ethnic group. The technical simplicity of the developed ARMS-PCR will facilitate the final diagnosis of the G6PD Aures.

A novel G6PD deleterious variant identified in three families with severe glucose-6-phosphate dehydrogenase deficiency

BACKGROUND

Glucose-6-phosphate dehydrogenase deficiency (D-G6PD) is an X-linked recessive disorder resulted from deleterious variants in the housekeeping gene Glucose-6-phosphate 1-dehydrogenase (G6PD), causing impaired response to oxidizing agents. Screening for new variations of the gene helps with early diagnosis of D-G6PD resulting in a reduction of disease related complications and ultimately increased life expectancy of the patients.

METHODS

One thousand five hundred sixty-five infants with pathological jaundice were screened for G6PD variants by Sanger sequencing all of the 13 exons, and the junctions of exons and introns of the G6PD gene.

RESULTS

We detected G6PD variants in 439 (28.1%) of the 1565 infants with pathological jaundice. In total, 9 types of G6PD variants were identified in our cohort; and a novel G6PD missense variant c.1118 T > C, p.Phe373Ser in exon 9 of the G6PD gene was detected in three families. Infants with this novel variant showed decreased activity of G6PD, severe anemia, and pathological jaundice, consistent with Class I G6PD deleterious variants. Analysis of the resulting protein's structure revealed this novel variant affects G6PD protein stability, which could be responsible for the pathogenesis of D-G6PD in these patients.

CONCLUSIONS

High rates of G6PD variants were detected in infants with pathological jaundice, and a novel Class I G6PD deleterious variants was identified in our cohort. Our data reveal that variant analysis is helpful for the diagnosis of D-G6PD in patients, and also for the expansion of the spectrum of known G6PD variants used for carrier detection and prenatal diagnosis.

Analysis of Glucose-6-Phosphate Dehydrogenase Genetic Polymorphism in the Hakka Population in Southern China

Background

In southern China, glucose-6-phosphate dehydrogenase (G6PD) deficiency is a significant health problem. The aim of this study was to investigate the molecular epidemiological characteristic of the G6PD gene among Chinese Hakka in southern Guangdong province.

Material/Methods

We screened 611 unrelated subjects for G6PD genetic polymorphism analyzed by a gene chip analysis for common Chinese G6PD mutations. G-6-PD enzyme activity was determined by use of the G-6-PD quantitative detection kit.

Results

Seven mutation sites were detected from subjects in our study. G6PD Canton (c.1376 G→T)(33.06%), G6PD Kaiping (c.1388 G→A)(30.67%), and polymorphism (c.1311 C→T)(25.89%) account for 89.62% of mutations, followed by G6PD Gaohe (c.95 A→G)(5.97%), G6PD Chinese-5 (c.1024 C→T)(3.58%), G6PD Maewo (c.1360 C→T)(0.39%), and G6PD Viangchan (c.871G→A)(0.39%).

Conclusions

We studied the genetic polymorphisms and frequencies of G6PD gene in the Hakka population of Meizhou. Our results coincide with the results among the Chinese Jiangxi Hakka population. It was consistent with previous research reports on Chinese people. There were differences in the results of reports from some other Asian populations. Our results could be useful for future prevention and control of G6PD deficiency aimed at the Chinese Hakka population.

An Observational Study of the Effect of Hemoglobinopathy, Alpha Thalassemia and Hemoglobin E on P. Vivax Parasitemia

Background

The protective effect of α-thalassemia, a common hematological disorder in Southeast Asia, against Plasmodium falciparum malaria has been well established. However, there is much less understanding of the effect of α-thalassemia against P. vivax. Here, we aimed to investigate the proportion of α-thalassemia including the impact of α-thalassemia and HbE on the parasitemia of P. vivax in Southeast Asian malaria patients in Thailand.

Methods

A total of 210 malaria patients, admitted to the Hospital for Tropical Diseases, Thailand during 2011–2012, consisting of 159 Myanmeses, 13 Karens, 26 Thais, 3 Mons, 3 Laotians, and 6 Cambodians were recruited. Plasmodium spp. and parasite densities were determined. Group of deletion mutation (--^SEA, −α^3.7, −α^4.2deletion) and substitution mutation (HbCS and HbE) were genotyped using multiplex gap-PCR and PCR-RFLP, respectively.

Results

In our malaria patients, 17/210 homozygous and 74/210 heterozygous −α^3.7 deletion were found. Only 3/210 heterozygous −α^4.2 and 2/210 heterozygous--^SEA deletion were detected. HbE is frequently found with 6/210 homozygotes and 35/210 heterozygotes. The most common thalassemia allele frequencies in Myanmar population were −α^3.7 deletion (0.282), followed by HbE (0.101), HbCS (0.013), −α^4.2 deletion (0.009), and --^SEA deletion (0.003). Only density of P. vivax in α-thalassemia trait patients (−α^3.7/−α^3.7, --^SEA/αα, −α^3.7/−α^4.2) but not in silent α-thalassemia (−α^3.7/αα, −α^4.2/αα, αα^CS/αα) were significantly higher compared with non-α-thalassemia patients (p=0.027). HbE did not affect P. vivax parasitemia. The density of P. falciparum significantly increased in heterozygous HbE patients (p=0.046).

Conclusions

Alpha-thalassemia trait is associated with high levels of P. vivax parasitemia in malaria patients in Southeast Asia.

Prevalence of Thalassemia and Glucose-6-Phosphate Dehydrogenase Deficiency in Newborns and Adults at the Ramathibodi Hospital, Bangkok, Thailand

Thalassemias and glucose-6-phosphate dehydrogenase (G6PD) deficiency are the most common inherited blood disorders. They are distributed among populations living in malaria endemic regions resulting in survival advantage from severe malaria disease. The aims of this study were to analyze the prevalence of thalassemias and G6PD deficiency at the Ramathibodi Hospital, Bangkok, Thailand. A total of 616 adult and 174 cord blood samples were collected and analyzed for red blood cell (RBC) parameters, hemoglobin (Hb) typing and DNA analysis for G6PD mutations and α-thalassemia (α-thal). The two most prominent types of thalassemia were heterozygous Hb E (HBB: c.79G>A), (19.5% in newborns and 35.6% in adults) followed by heterozygous α-thal-2 [-α^3.7 (rightward) deletion] at 18.7% in newborns and 19.5% in adults. After performing G6PD genotyping using multiplex amplification refractory mutation system-polymerase chain reaction (multiplex ARMS-PCR) for 10 G6PD mutations, the prevalence of G6PD mutation was found in 12.0% of newborns and 11.7% of adults. The G6PD Viangchan [871 (G>A)] is the most common G6PD mutation in newborns (42.9%) and adults (52.8%). In addition, coinheritance of various types of thalassemia with G6PD deficiency were found. The results indicated that heterozygous Hb E and G6PD Viangchan are predominant both in newborns and adults in this study.

Lower reference limits of quantitative cord glucose-6-phosphate dehydrogenase estimated from healthy term neonates according to the Clinical and Laboratory Standards Institute guidelines: a cross sectional retrospective study

BACKGROUND

Previous studies have reported the lower reference limit (LRL) of quantitative cord glucose-6-phosphate dehydrogenase (G6PD), but they have not used approved international statistical methodology. Using common standards is expecting to yield more true findings. Therefore, we aimed to estimate LRL of quantitative G6PD detection in healthy term neonates by using statistical analyses endorsed by the International Federation of Clinical Chemistry (IFCC) and the Clinical and Laboratory Standards Institute (CLSI) for reference interval estimation.

METHODS

This cross sectional retrospective study was performed at King Abdulaziz Hospital, Saudi Arabia, between March 2010 and June 2012. The study monitored consecutive neonates born to mothers from one Arab Muslim tribe that was assumed to have a low prevalence of G6PD-deficiency. Neonates that satisfied the following criteria were included: full-term birth (37 weeks); no admission to the special care nursery; no phototherapy treatment; negative direct antiglobulin test; and fathers of female neonates were from the same mothers' tribe. The G6PD activity (Units/gram Hemoglobin) was measured spectrophotometrically by an automated kit. This study used statistical analyses endorsed by IFCC and CLSI for reference interval estimation. The 2.5th percentiles and the corresponding 95% confidence intervals (CI) were estimated as LRLs, both in presence and absence of outliers.

RESULTS

207 males and 188 females term neonates who had cord blood quantitative G6PD testing met the inclusion criteria. Method of Horn detected 20 G6PD values as outliers (8 males and 12 females). Distributions of quantitative cord G6PD values exhibited a normal distribution in absence of the outliers only. The Harris-Boyd method and proportion criteria revealed that combined gender LRLs were reliable. The combined bootstrap LRL in presence of the outliers was 10.0 (95% CI: 7.5-10.7) and the combined parametric LRL in absence of the outliers was 11.0 (95% CI: 10.5-11.3).

CONCLUSION

These results contribute to the LRL of quantitative cord G6PD detection in full-term neonates. They are transferable to another laboratory when pre-analytical factors and testing methods are comparable and the IFCC-CLSI requirements of transference are satisfied. We are suggesting using estimated LRL in absence of the outliers as mislabeling G6PD-deficient neonates as normal is intolerable whereas mislabeling G6PD-normal neonates as deficient is tolerable.

Apelin gene polymorphism influences apelin expression and obesity phenotypes in Chinese women

BACKGROUND

Apelin, which is a newly identified adipokine, is related to obesity and insulin resistance. A positive correlation between plasma apelin concentrations and obesity traits was reported.

OBJECTIVE

We tested associations between apelin gene (APLN) polymorphisms, BMI, and waist circumference (WC) and compared APLN expression levels in cells of different genotypes.

DESIGN

Four tagging single nucleotide polymorphisms (SNPs) and one promoter SNP were genotyped in 1627 Chinese subjects. Because APLN was located on the chromosome X, statistical analyses were conducted in a sex-specific manner. Adipocytes of different genotypes were derived from the omental fat tissue of 10 women. We treated the primary adipocytes with high glucose plus insulin because of a close relation between insulin resistance and obesity.

RESULTS

SNP rs3115757 was significantly associated with BMI and WC in women. Compared with the CG or GG genotype, the CC genotype had an OR of 2.07 (95% CI: 1.23, 3.49) for having a high WC (P = 0.006) and an OR of 2.29 (95% CI: 1.25, 4.19) for having a BMI (in kg/m(2)) ≥27 (P = 0.007). None of the SNPs was associated with BMI or WC in men. In adipocytes that carried the CC genotype of rs3115757, APLN messenger RNA levels and protein concentrations were higher in cells treated with high glucose plus insulin than in those with normal glucose. There was no difference between the 2 conditions in adipocytes of the CG or GG genotype.

CONCLUSION

Both association and functional studies suggested that APLN polymorphisms were associated with risks of obesity phenotypes.

Fatal Chromobacterium violaceum septicaemia in northern Laos, a modified oxidase test and post-mortem forensic family G6PD analysis

Background

Chromobacterium violaceum is a Gram negative facultative anaerobic bacillus, found in soil and stagnant water, that usually has a violet pigmented appearance on agar culture. It is rarely described as a human pathogen, mostly from tropical and subtropical areas.

Case presentation

A 53 year-old farmer died with Chromobacterium violaceum septicemia in Laos. A modified oxidase method was used to demonstrate that this violacious organism was oxidase positive. Forensic analysis of the glucose-6-phosphate dehydrogenase genotypes of his family suggest that the deceased patient did not have this possible predisposing condition.

Conclusion

C. violaceum infection should be included in the differential diagnosis in patients presenting with community-acquired septicaemia in tropical and subtropical areas. The apparently neglected but simple modified oxidase test may be useful in the oxidase assessment of other violet-pigmented organisms or of those growing on violet coloured agar.

Coexistence of five G6PD variants indicates ethnic complexity of Phuket islanders, Southern Thailand

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy in humans. The prevalence of G6PD deficiency and its molecular basis were studied in Phuket islanders, Southern Thailand. A total of 345 volunteers (123 males and 222 females) were recruited in this study. Infection with Plasmodium falciparum or Plasmodium vivax was not detected in any of these subjects by polymerase chain reaction (PCR)-based diagnosis. G6PD-deficient individuals were identified with the WST-8/1-methoxy PMS method. The molecular basis of G6PD deficiency was investigated by PCR-direct sequencing procedures or PCR-restriction enzyme fragment length polymorphism assays. The numbers of individuals showing severe and mild G6PD deficiency were 14 and 21, respectively. A high prevalence of G6PD deficiency was observed in subjects with Moken (15.4%) or Thai (15.5%) ethnic background. G6PD Mahidol (487G>A) (n=14), G6PD Viangchan (871G>A) (n=11), G6PD Gaohe (95A>G) (n=2), G6PD Kaiping (1388G>A) (n=1), and G6PD Kerala-Kalyan (949G>A) (n=1) were identified. The results suggest that several groups of people of the Asian Continent, such as Burmese, Laotian or Cambodian, Thai and Chinese, participated in the establishment of the ethnic identity of the current ethnic groups of Phuket Island.

Diagnosis of red cell G6PD deficiency in rural Burkina Faso: comparison of a rapid fluorescent enzyme test on filter paper with polymerase chain reaction based genotyping

Glucose-6-phosphate dehydrogenase (G6PD) deficient individuals are at increased risk of developing haemolysis following treatment with various antimalarial drugs. Reliable field tests for G6PD deficiency are thus needed in chemotherapy studies and their validity has to be assessed. In two phase II clinical trials on methylene blue (MB) antimalarial therapy in rural Burkina Faso, paediatric and adult participants were tested for G6PD deficiency. The results of a haemoglobin-adjusted nicotinamide adenine dinucleotide phosphate (NADPH) fluorescence test on paper (NFP test) were compared with polymerase chain reaction (PCR)-based G6PD genotyping also using blood samples on filter papers. This is the first study comparing sensitivity and specificity of the two methods. There was good agreement between the NFP test results and the PCR findings. The estimate of the sensitivity of the NFP test was 98.2% (95.8-99.6%) and the specificity was 97.1% (94.2-99.2%). In conclusion, the NFP assay is a reliable and inexpensive method for large-scale G6PD deficiency screening in rural West Africa.

Molecular heterogeneity of glucose-6-phosphate dehydrogenase (G6PD) variants in the south of Thailand and identification of a novel variant (G6PD Songklanagarind)

Two hundred and twenty-five G6PD-deficient subjects in Songklanagarind Hospital in the south of Thailand comprising 210 males and 15 females were studied. Neonatal jaundice was detected in 85% of these patients. Acute hemolysis related to infection was detected in 17.3% of the G6PD-deficient subjects. Drug-induced acute hemolysis was detected in 1.8% and favism was observed in 3.6% of G6PD-deficient patients. The molecular analysis was performed on 134 G6PD-deficient individuals by a combination of PCR-RFLP, multiplex polymerase chain reaction by multiple tandem forward primers and a common reverse primer assay (MPTP) and DNA sequencing to characterize the mutations of the samples with abnormal MPTP bands. We found 10 different missense G6PD mutations and the three most common variants were G6PD Viangchan 871,G-->A (31.3%), G6PD Kaiping 1388,G-->A (20.1%) and G6PD Mahidol 487,G-->A (17.2%) followed by G6PD Canton 1376,G-->T (9.7%), G6PD Union 1360,C-->T (2.2%), G6PD Gaohe 95,A-->G (1.5%), G6PD Quing Yuan 392,G-->T (0.7%), G6PD Mediterranean 563,C-->T (0.7%), G6PD Songklanagarind 196,T-->A (0.7%), silent mutation 1311,C-->T (6.7%), and uncharacterized variant (9%). A novel missense mutation at codon 196, TTC-->ATC in exon 4 of the G6PD gene predicting a single amino acid substitution, Phe66Ile was identified and we designated this novel class II variant as G6PD Songklanagarind. The G6PD variants among the Thais in the southern part are heterogeneous and G6PD Viangchan, Kaiping, Mahidol, and Canton variants account for about 78% of the cases. Our findings provide some evidence that G6PD Viangchan and Mahidol are common Southeast Asian variants and support the theory of genetic drifts throughout Southeast Asia.

Molecular characterization of G6PD deficiency in Cyprus

In the present study, we determined the frequency of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Cyprus using two different procedures in two separate adult population groups: a semiquantitative fluorescence test on blood spotted on filter paper and a quantitative spectrophotometric test on liquid blood. The frequency of G6PD deficiency among healthy adult males was found to be 5.1% using the semiquantitative procedure and 6.4% using the quantitative procedure. Neither method was able to detect all the expected female heterozygotes (5.3% and 47.1% of the expected number, respectively). A total of 21 male hemizygotes, 1 female homozygote and 9 female heterozygotes that tested positive for G6PD deficiency were studied at the molecular level. All 32 chromosomes were genotyped and five different mutations were identified. The Mediterranean mutation in exon 6 (563C-->T) (Ser188Phe) was found to be the most common variant in the Cypriot population, accounting for 52.6% of the deficient alleles. In the remaining chromosomes, four different mutations were identified: three known mutations, Kaiping 1388G-->A (Arg463His), Chatham 1003G-->A (Ala335Thr) and Acrokorinthos 463C-->G (His155Asp), and one previously undescribed mutation in exon 3, 148C-->T (Pro50Ser), which we called G6PD Kambos. We conclude that the frequency of G6PD deficiency in Cypriot males is 6.4%, and that this deficiency is the result of several different mutations. Although all the individuals carrying the Mediterranean variant can be detected using a semiquantitative screening method, a quantitative enzyme measurement is required to detect the G6PD variants with less severe enzyme deficiencies, while the most appropriate method for heterozygote detection is DNA analysis.

Molecular heterogeneity of glucose-6-phosphate dehydrogenase deficiency in Mexico: overall results of a 7-year project

Several years ago, a project aiming to determine (i) the molecular basis of G-6-PD deficiency, (ii) the distribution of four different mutant alleles previously detected, and (iii) the whole of polymorphic alleles that account for the overall prevalence of G-6-PD deficiency in Mexico was implemented. Nearly 5000 individuals-from the general population and patients with hemolytic anemia-belonging to at least 14 States were screened for G-6-PD deficiency. Seventy-six G-6-PD-deficient subjects were detected and the prevalence of G-6-PD deficiency in 4777 individuals from the general population was 0.71%. Screening for both mutations associated with enzyme deficiency and silent polymorphisms at the G-6-PD gene was performed in the enzyme-deficient individuals by PCR-SSCP combined with restriction enzyme analysis; the silent polymorphisms as well as the nondeficient variant G-6-PD A(376G) were also investigated in 366 G-6-PD normal individuals from the general population. In 88% of the enzyme-deficient individuals it was possible to define the mutation responsible and the type G-6-PD A- variants were the more common in both individuals from the general population and patients with hemolytic anemia. G-6-PD deficiency is heterogeneous at the DNA level in Mexico and up to date 10 different variants-8 in the present project and 2 previously-have been observed: G-6-PD A(-202A/376G), G-6-PD A(-376G/968C), G-6-PD Santamaria(376G/542T), G-6-PD Vanua Lava(383C), G-6-PD Tsukui(del561-563), G-6-PD "Mexico City"(680A), G-6-PD Seattle(844C), G-6PD Guadalajara(1159T),G-6-PD Nashville(1178A), and G-6-PD Union(1360T). The G-6-PD A(-) variants have a relatively homogeneous distribution and along with G-6-PD Santamaria(376G/542T), they account for 82% of the overall prevalence of G-6-PD deficiency in Mexico; all other seven variants represent 9% of the mutant alleles examined, and in the rest of the chromosomes the mutation responsible for the enzyme deficiency remains to be defined. Several of the variants observed in Mexico are common in Africa, South Europe, and Southeast Asia. The prevalence for the variant G-6-PD A(376G) was 1.64%. From 256 possible haplotypes only 14 were observed and haplotype analysis suggests that some of the G-6-PD variants probably were imported to Mexico by population flow from South Europe, Africa, and Southeast Asia. This work (i) identified the G-6-PD variants prevalent in Mexico, (ii) defines their geographical distribution, (iii) contributes to the knowledge of the genetic structure of the Mexican population, and (iv) will facilitate the molecular analysis of the G-6-PD gene in enzyme-deficient Mexican individuals.

Hematologic disorders in children from southeast Asia

The overall laboratory features of the common RBC disorders occurring in Southeast Asians is summarized in Table 4. These erythrocyte disorders will continue to be important public health issues, and it has been predicted that most new cases of thalassemia in the United States will occur in this population group. The fertility rate in Southeast Asian families is very high, with an average of more than five children delivered by each married woman. This number of children is consistent with perceptions of ideal family size, and, to date, no evidence suggests any change in the size of Southeast Asian families who now reside in the United States. Moreover, attitudes about health care, reasons why one seeks medical attention, and a variety of other cultural issues may impair the effectiveness of genetic counseling and other preventive measures designed to reduce the incidence of serious blood diseases. Genetic screening and prenatal diagnosis clearly have led to a markedly decreased incidence of homozygous thalassemia disorders in high-risk Mediterranean populations throughout the world. With further assimilation into Western culture, a similar disease may occur in the Southeast Asian population also.

Neonatal jaundice and molecular mutations in glucose-6-phosphate dehydrogenase deficient newborn infants

Molecular mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene and clinical manifestations of neonatal jaundice in 112 male and 50 female Chinese neonates with G6PD deficiency were studied. In the 112 males, the nucleotide (nt) 1376 (G-->T) mutation was the dominant type (50.0%), followed by nt 1388 (G-->A) (16.1%), nt 493 (A-->G) (8.0%), nt 1024 (C-->T) (6.2%), nt 95 (A-->G) (5.4%), nt 392 (G-->T) (1.8%), nt 487 (G-->A) (1.8%), nt 871 (G-->A) (0.9%), and nt 1360 (C-->T) (0.9%). The nt 871 variant has not been reported in Taiwan before. The occurrence rates for nt 1376, nt 1388, nt 493, nt 95, and nt 1024 mutations in the 50 females were 44.0%, 18.0%, 12.0%, 6.0%, and 6.0%, respectively. The type of G6PD mutation in 10 male and 7 female neonates has not been identified yet. Although G6PD deficient neonates had higher frequency of phototherapy than G6PD normal neonates in both sexes, a significant difference in the prevalence of hyperbilirubinemia (peak bilirubin > or = 15.0 mg/dl) between G6PD deficient and normal neonates was found only in males. Further analysis showed that duration of phototherapy was longer in G6PD deficient male neonates than in the control group, while the outcome of phototherapy was better in subjects with non-nt 1376 mutations than subjects with the nt 1376 mutation. Most (78.3%) of the 23 G6PD deficient neonates who subsequently suffered from neonatal hyperbilirubinemia carried the nt 1376 mutation. The results of this study indicate that the nucleotide substitution at 1376 is the most common and important mutation for G6PD deficiency in Chinese neonates in Taiwan.