Hyperbilirubinemia among African American, glucose-6-phosphate dehydrogenase-deficient neonates

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.

Preliminary Investigation into the Prevalence of G6PD Deficiency in a Pediatric African American Population Using a Near-Patient Diagnostic Platform

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is prevalent in the African American population. We identified eighteen G6PD-deficient samples (9%) in a study of residual, de-identified whole blood specimens from 200 African American pediatric patients using a point-of-care instrument. This highlights the possibility of a rapid time to result for G6PD testing, which can be valuable in some clinical scenarios.

Glucose-6-phosphate dehydrogenase deficiency among neonates with jaundice in Africa; systematic review and meta-analysis

Background

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic disorder caused by a structural abnormality in the enzyme. G6PD deficiency is most prevalent among African, Asian, and Mediterranean people. This study aimed to investigate how prevalent G6PD deficiency is in African neonates with jaundice.

Methods

The public sources, such as PubMed, Science Direct, Google Scholar, and Africa Journal Online were searched for articles that reported the prevalence of G6PD deficiency published before March 21st, 2022. The Joanna Briggs Institute's (JBI) critical assessment checklist was used to evaluate the quality of individual studies. STATA-17 was used to do the statistical analysis. The pooled prevalence of G6PD deficiency in neonates with jaundice in Africa was calculated using a forest plot and a random effects model. I2 statistics and Galbraith plots were used to assess heterogeneity. Publication bias was assessed using a funnel plot and Egger's statistical test.

Results

Ten studies involving 1555 neonates with jaundice were involved in the study. G6PD deficiency was prevalent in 24.60% of African neonates with jaundice (95% CI:12.47-36.74) with considerable heterogeneity (I2 = 100%). Nigerian neonates with jaundice had the highest G6PD deficiency (49.67%), whereas South Africans had the lowest (3.14%).

Conclusion

G6PD deficiency has been implicated in a significant portion of African neonates with jaundice, notwithstanding the need for greater research on predisposing variables from other countries. Therefore, it should be thought of performing screening and diagnostic laboratory tests for G6PD deficiency.

Higher ETCOc predicts longer phototherapy treatment in neonatal hyperbilirubinemia

Objective

This study aimed to evaluate the predictive performance of end-tidal carbon monoxide corrected to ambient carbon monoxide (ETCOc) values phototherapy in neonates with significant hyperbilirubinemia.

Methods

A prospective study was conducted on neonates with significant hyperbilirubinemia who received phototherapy between 3 and 7 days of life. The breath ETCOc and serum total bilirubin of the recruited infants were measured on admission.

Results

The mean ETCOc at admission in 103 neonates with significant hyperbilirubinemia was 1.70 ppm. The neonates were categorized into two groups: phototherapy duration ≤72 h (n = 87) and >72 h (n = 16) groups. Infants who received phototherapy for >72 h had significantly higher ETCOc (2.45 vs. 1.60, P = 0.001). The cutoff value of ETCOc on admission for predicting longer phototherapy duration was 2.4 ppm, with a sensitivity of 62.5% and specificity of 88.5%, yielding a 50% positive predictive value and a 92.7% negative predictive value.

Conclusion

ETCOc on admission can help predict the duration of phototherapy in neonates with hyperbilirubinemia, facilitate clinicians to judge disease severity, and make clinical communication easier and more efficient.

Hyperbilirubinemia in the Term Infant: Re-evaluating What We Think We Know

This article attempts to highlight contemporary issues relating to term neonatal hyperbilirubinemia and to focus attention on controversial issues and concepts with the potential to effect change in clinical approach. On the one hand, the focus is bilirubin neurotoxicity, which is now known to encompass a wide, diverse spectrum of features. The various aspects of this spectrum are outlined and defined. On the other hand, bilirubin also possesses antioxidant properties. As such, mild hyperbilirubinemia is suggested as actually offering the neonate some protective advantage.

A novel point-of-care device for measuring glucose-6-phosphate dehydrogenase enzyme deficiency

Extreme hyperbilirubinemia can cause bilirubin neurotoxicity. Infants with glucose-6-phosphate dehydrogenase (G6PD) deficiency can develop hemolysis and thus are at high risk. We evaluated a device that quantitatively measures G6PD activity kinetically using digital microfluidics (DMF). Intra- and inter-instrument and -day imprecision (CVs) were first assessed. G6PD activity in 86 samples was then measured and compared between DMF and 2 reference methods. Overall DMF reproducibility was 3.8% over 5 days by 2 operators on 2 instruments. Mean intra- and inter-instrument variabilities were 3.6% and 3.9%, respectively (n = 28), with a user variability of 4.3%. Mean G6PD activity was 6.40±4.62 and 6.37±4.62 U/g hemoglobin for DMF and Reference Methods 1 (n = 46) and 12.15±3.86 and 11.48±1.55 for DMF and 2 (n = 40), respectively, and strongly correlated (r = 0.95 and 0.95) with mean biases of +0.04±2.90 and +0.67±1.55 for methods 1 and 2, respectively. The novel device could be used for early newborn G6PD screening.

The potential link between inherited G6PD deficiency, oxidative stress, and vitamin D deficiency and the racial inequities in mortality associated with COVID-19

There is a marked variation in mortality risk associated with COVID-19 infection in the general population. Low socioeconomic status and other social determinants have been discussed as possible causes for the higher burden in African American communities compared with white communities. Beyond the social determinants, the biochemical mechanism that predisposes individual subjects or communities to the development of excess and serious complications associated with COVID-19 infection is not clear. Virus infection triggers massive ROS production and oxidative damage. Glutathione (GSH) is essential and protects the body from the harmful effects of oxidative damage from excess reactive oxygen radicals. GSH is also required to maintain the VD-metabolism genes and circulating levels of 25-hydroxyvitamin D (25(OH)VD). Glucose-6-phosphate dehydrogenase (G6PD) is necessary to prevent the exhaustion and depletion of cellular GSH. X-linked genetic G6PD deficiency is common in the AA population and predominantly in males. Acquired deficiency of G6PD has been widely reported in subjects with conditions of obesity and diabetes. This suggests that individuals with G6PD deficiency are vulnerable to excess oxidative stress and at a higher risk for inadequacy or deficiency of 25(OH)VD, leaving the body unable to protect its 'oxidative immune-metabolic' physiological functions from the insults of COVID-19. An association between subclinical interstitial lung disease with 25(OH)VD deficiencies and GSH deficiencies has been previously reported. We hypothesize that the overproduction of ROS and excess oxidative damage is responsible for the impaired immunity, secretion of the cytokine storm, and onset of pulmonary dysfunction in response to the COVID-19 infection. The co-optimization of impaired glutathione redox status and excess 25(OH)VD deficiencies has the potential to reduce oxidative stress, boost immunity, and reduce the adverse clinical effects of COVID-19 infection in the AA population.

Combating the Hidden Health Disparity of Kernicterus in Black Infants: A Review

IMPORTANCE

Kernicterus is a devastating, permanently disabling neurologic condition resulting from bilirubin neurotoxicity. Black neonates account for more than 25% of kernicterus cases in the US, despite making up only approximately 14% of all births. This is a largely overlooked health disparity.

OBSERVATIONS

The black kernicterus health disparity exists despite a lower overall incidence of clinically significant hyperbilirubinemia among black neonates, a paradox recently explained by a previously unrecognized risk for hazardous hyperbilirubinemia. Aligned with national and global health initiatives to reduce or eliminate health disparities, this review highlights the multiple biologic and nonbiologic factors contributing to kernicterus risk in black infants and approaches to reduce this health disparity. This includes both parent-level and clinician-level kernicterus prevention strategies, with an emphasis on improving parental health literacy on neonatal jaundice and acute bilirubin encephalopathy and clinician awareness of the key factors that contribute to hazardous hyperbilirubinemia risk in this vulnerable group. Parent-level prevention strategies include efforts to improve their health literacy on neonatal jaundice and acute bilirubin encephalopathy and empower care seeking for jaundice. Clinician-level prevention strategies include efforts to eliminate community and institutional barriers that impede access to care, heighten clinician awareness of the factors that contribute to kernicterus risk in this vulnerable patient group, and strengthen newborn hyperbilirubinemia management and bilirubin surveillance.

CONCLUSIONS AND RELEVANCE

There are multiple opportunities for intervention to reduce black kernicterus risk. Although kernicterus is a rare disorder, the incidence among black infants is not a trivial matter nor are efforts to prevent kernicterus. While the multiple interacting biologic and nonbiologic contributors to increased kernicterus risk among black infants pose a considerable challenge to clinicians, there are opportunities for intervention to reduce this risk and health disparity. Continued study is imperative to understand the current scope of kernicterus and its occurrence in black neonates.

Can Vitamin D and L-Cysteine Co-Supplementation Reduce 25(OH)-Vitamin D Deficiency and the Mortality Associated with COVID-19 in African Americans?

Early reports indicate an association between the severity of the COVID-19 infection and the widespread 25-hydroxy vitamin D deficiency known to exist in populations around the world. Vitamin D deficiency is extremely common among African American (AA) communities, where the COVID-19 infection rate is three-fold higher, and the mortality rate nearly six-fold higher, compared with rates in predominantly white communities. COVID-19 infection primarily affects the lungs and airways. Previous reports have linked 25-hydroxy vitamin D deficiency with subclinical interstitial lung disease. AA are at risk for lower cellular glutathione (GSH) levels, and GSH deficiency epigenetically impairs VD biosynthesis pathway genes. Compared with vitamin D alone, co-supplementation of vitamin D and L-cysteine (a GSH precursor) showed a better efficacy in improving levels of GSH and VD-regulatory genes at the cellular/tissue level, increasing 25(OH) vitamin D levels, and reducing inflammation biomarkers in the blood in mice studies. We propose that randomized clinical trials are needed to examine the potential of co-supplementation with anti-inflammatory antioxidants, vitamin D and L-cysteine in correcting the 25(OH)VD deficiency and preventing the 'cytokine storm,' one of the most severe consequences of infection with COVID-19, thereby preventing the adverse clinical effects of COVID-19 infection in the vulnerable AA population.

Indirect neonatal hyperbilirubinemia in hospitalized neonates on the Thai-Myanmar border: a review of neonatal medical records from 2009 to 2014

BACKGROUND

Indirect neonatal hyperbilirubinemia (INH) is a common neonatal disorder worldwide which can remain benign if prompt management is available. However there is a higher morbidity and mortality risk in settings with limited access to diagnosis and care. The manuscript describes the characteristics of neonates with INH, the burden of severe INH and identifies factors associated with severity in a resource-constrained setting.

METHODS

We conducted a retrospective evaluation of anonymized records of neonates hospitalized on the Thai-Myanmar border. INH was defined according to the National Institute for Health and Care Excellence guidelines as 'moderate' if at least one serum bilirubin (SBR) value exceeded the phototherapy threshold and as 'severe' if above the exchange transfusion threshold.

RESULTS

Out of 2980 records reviewed, 1580 (53%) had INH within the first 14 days of life. INH was moderate in 87% (1368/1580) and severe in 13% (212/1580). From 2009 to 2011, the proportion of severe INH decreased from 37 to 15% and the mortality dropped from 10% (8/82) to 2% (7/449) coinciding with the implementation of standardized guidelines and light-emitting diode (LED) phototherapy. Severe INH was associated with: prematurity (< 32 weeks, Adjusted Odds Ratio (AOR) 3.3; 95% CI 1.6-6.6 and 32 to 37 weeks, AOR 2.2; 95% CI 1.6-3.1), Glucose-6-phosphate dehydrogenase deficiency (G6PD) (AOR 2.3; 95% CI 1.6-3.3), potential ABO incompatibility (AOR 1.5; 95% CI 1.0-2.2) and late presentation (AOR 1.8; 95% CI 1.3-2.6). The risk of developing severe INH and INH-related mortality significantly increased with each additional risk factor.

CONCLUSION

INH is an important cause of neonatal hospitalization on the Thai-Myanmar border. Risk factors for severity were similar to previous reports from Asia. Implementing standardized guidelines and appropriate treatment was successful in reducing mortality and severity. Accessing to basic neonatal care including SBR testing, LED phototherapy and G6PD screening can contribute to improve neonatal outcomes.

Heme oxygenase-1 promoter polymorphisms: do they modulate neonatal hyperbilirubinemia?

The role of genetic factors in the modulation of serum bilirubin levels and the pathophysiology of neonatal hyperbilirubinemia is being increasingly recognized. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme by which heme is catabolized to biliverdin and thence to bilirubin, with the simultaneous release of equimolar quantities of ferrous iron (Fe³⁺) and carbon monoxide. Polymorphisms of the HO-1 gene promoter may modulate transcriptional activity, thereby augmenting or attenuating HO-1 expression with resultant modulation of the production of bilirubin. Few studies have related these polymorphisms to neonatal bilirubin metabolism and have reported conflicting results. In this clinical review, we surveyed the role of HO-1 gene promoter polymorphisms in the control of bilirubin production and further considered their role, if any, in the pathophysiology of neonatal hyperbilirubinemia.

Markers of oxidative stress in umbilical cord blood from G6PD deficient African newborns

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked disorder that affects as many as 400 million people worldwide, making it the most common enzymatic defect. Subjects with G6PD deficiency are more likely to develop neonatal hyperbilirubinemia potentially leading to kernicterus and are at increased risk for acute hemolytic anemia when exposed to pro-oxidant compounds such as anti-malarial drugs. We collected umbilical cord blood from 300 males born in Uganda to assess for novel markers of systemic oxidative stress. We determined that 10.7% of the samples collected were G6PD A- deficient (G202A/A376G) and when these were compared with unaffected controls, there was significantly higher 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentration, elevated ferritin, increased leukocyte count and higher small molecule antioxidant capacity. These data suggest increased baseline oxidative stress and an elevated antioxidant response in umbilical cord blood of patients with G6PD deficiency.

Point-of-Care Quantitative Measure of Glucose-6-Phosphate Dehydrogenase Enzyme Deficiency

BACKGROUND AND OBJECTIVES

Widespread newborn screening on a point-of-care basis could prevent bilirubin neurotoxicity in newborns with glucose-6-phosphate dehydrogenase (G6PD) deficiency. We evaluated a quantitative G6PD assay on a digital microfluidic platform by comparing its performance with standard clinical methods.

METHODS

G6PD activity was measured quantitatively by using digital microfluidic fluorescence and the gold standard fluorescence biochemical test on a convenience sample of 98 discarded blood samples. Twenty-four samples were designated as G6PD deficient.

RESULTS

Mean ± SD G6PD activity for normal samples using the digital microfluidic method and the standard method, respectively, was 9.7 ± 2.8 and 11.1 ± 3.0 U/g hemoglobin (Hb), respectively; for G6PD-deficient samples, it was 0.8 ± 0.7 and 1.4 ± 0.9 U/g Hb. Bland-Altman analysis determined a mean difference of -0.96 ± 1.8 U/g Hb between the digital microfluidic fluorescence results and the standard biochemical test results. The lower and upper limits for the digital microfluidic platform were 4.5 to 19.5 U/g Hb for normal samples and 0.2 to 3.7 U/g Hb for G6PD-deficient samples. The lower and upper limits for the Stanford method were 5.5 to 20.7 U/g Hb for normal samples and 0.1 to 2.8 U/g Hb for G6PD-deficient samples. The measured activity discriminated between G6PD-deficient samples and normal samples with no overlap.

CONCLUSIONS

Pending further validation, a digital microfluidics platform could be an accurate point-of-care screening tool for rapid newborn G6PD screening.

Association between G6PD deficiency and hyperbilirubinemia in neonates: a meta-analysis

Hyperbilirubinemia is prevalent in newborns and multiple factors are responsible for the occurrence of neonatal hyperbilirubinemia. G6PD (Glucose-6-Phosphate Dehydrogenase) deficiency is recognized as one of the risk factors. However, many pediatricians did not take into account the probable effect of G6PD-deficiency when severe neonatal hyperbilirubinemia occurred. The aim of the present study was to perform a meta-analysis to investigate whether G6PD-deficiency increases the risk of hyperbilirubinemia and phototherapy in newborn. We searched PubMed and Embase databases for eligible articles according to explicit study inclusion and exclusion criteria. Risk ratios (RRs) and 95% confidence interval (CI) were selected as the evaluation indexes. Cochrane Q and I(2) test were utilized to assess the heterogeneity among studies. A total of five cohort studies were included in this meta-analysis. There were 21,585 participants enrolled in these studies including 877 newborns with hyperbilirubinemia and 261 newborns receiving phototherapy. Comparison of the incidence of hyperbilirubinemia in newborns with G6PD-deficiency to the ones with normal G6PD in each study yielded a pooled RR of 3.92 (95% CI, 2.13-7.20; P <.0001). The pooled RR of receiving phototherapy in G6PD-deficiency neonates is 3.01 (95% CI, 2.20-4.12; P <.0001) when compared to G6PD normal neonates. This study revealed a significant correlation between G6PD-deficiency and neonatal hyperbilirubinemia, as well as G6PD-deficiency and phototherapy. G6PD-deficient newborns have higher risk of hyperbilirubinemia and phototherapy than the ones with normal G6PD. Monitoring the level of G6PD in newborns is important for predicting the occurrence of hyperbilirubinemia.

Neonatal hemolysis and risk of bilirubin-induced neurologic dysfunction

The pathologic phenotype of severe hyperbilirubinemia in the newborn infant is primarily due to excessive bilirubin production and/or impaired conjugation, resulting in an increased bilirubin load. This may, in turn, increase an infant's risk for the development of bilirubin-induced neurologic dysfunction (BIND). The highest-risk infants are those with increased bilirubin production rates due to hemolysis. Several immune and non-immune conditions have been found to cause severe hemolysis, and these are often exacerbated in those infants with perinatal sepsis and genetic predispositions. Therefore, identification of these infants, with novel technologies, is paramount in reducing the incidence of BIND and the long-term neurologic sequelae for these at-risk infants.

Glucose-6-phosphate-dehydrogenase deficiency and its correlation with other risk factors in jaundiced newborns in Southern Brazil

OBJECTIVE

To evaluate the correlation between glucose-6-phosphate-dehydrogenase (G6PD) deficiency and neonatal jaundice.

METHODS

Prospective, observational case-control study was conducted on 490 newborns admitted to Hospital de Clínicas de Porto Alegre for phototherapy, who all experienced 35 or more weeks of gestation, from March to December 2007. Enzymatic screening of G6PD activity was performed, followed by PCR.

RESULTS

There was prevalence of 4.6% and a boy-girl ratio of 3:1 in jaundiced newborns. No jaundiced neonate with ABO incompatibility presented G6PD deficiency, and no Mediterranean mutation was found. A higher proportion of deficiency was observed in Afro-descendants. There was no association with UGT1A1 variants.

CONCLUSIONS

G6PD deficiency is not related to severe hyperbilirubinemia and considering the high miscegenation in this area of Brazil, other gene interactions should be investigated.

Early neonatal bilirubin, hematocrit, and glucose-6-phosphate dehydrogenase status

OBJECTIVE

To document the patterns of bilirubin and hematocrit values among glucose-6-phosphate dehydrogenase (G6PD)-deficient and G6PD-normal Nigerian neonates in the first week of life, in the absence of exposure to known icterogenic agents.

METHODS

The G6PD status of consecutive term and near-term neonates was determined, and their bilirubin levels and hematocrits were monitored during the first week of life. Infants were stratified into G6PD deficient, intermediate, and normal on the basis of the modified Beutler's fluorescent spot test. Means of total serum bilirubin (TSB) and hematocrits of the 3 groups of infants were compared.

RESULTS

The 644 neonates studied comprised 353 (54.8%) boys and 291 (45.2%) girls and 540 (83.9%) term and 104 (16.1%) near-term infants. They consisted of 129 (20.0%) G6PD-deficient, 69 (10.7%) G6PD-intermediate, and 446 (69.3%) G6PD-normal neonates. The G6PD-deficient and G6PD-intermediate infants had higher mean TSB than their G6PD-normal counterparts at birth and throughout the first week of life (P < .001). Mean peak TSB levels were 14.1 (9.48), 10.2 (3.8), and 6.9 (3.3) mg/dL for G6PD-deficient, G6PD-intermediate, and G6PD-normal neonates, respectively. Peak TSB was attained on approximately day 4 in all 3 groups, and trends in TSB were similar. Mean hematocrits at birth were similar in the 3 G6PD groups. However, G6PD-deficient and -intermediate infants had higher declines in hematocrit, bilirubin levels, and need for phototherapy than G6PD-normal infants (P < .001).

CONCLUSIONS

The G6PD-deficient and G6PD-intermediate neonates had a higher risk of neonatal hyperbilirubinemia and would therefore need greater monitoring in the first week of life, even without exposure to known icterogenic agents.

End-tidal carbon monoxide and hemolysis

Hemolytic disease in newborns can result from a number of conditions, which can place such infants at an increased risk for the development of severe hyperbilirubinemia. Because the catabolism of heme produces equimolar amounts of carbon monoxide (CO) and bilirubin, measurements of end-tidal breath CO (corrected for ambient CO) or ETCOc can serve as an index of hemolysis as well as of bilirubin production from any cause. Elevated levels of ETCOc have been correlated with blood carboxyhemoglobin levels and thus hemolysis. However, the detection of hemolysis can be a clinically challenging problem in newborns. Here, we describe the importance of determining ETCOc levels and their application in identifying infants at risk for developing hyperbilirubinemia associated with hemolysis and other causes of increased bilirubin production.

Is it accurate to separate glucose-6-phosphate dehydrogenase activity in neonatal hyperbilirubinemia as deficient and normal?

BACKGROUND

The aim of this study was to investigate glucose 6-phosphate dehydrogenase (G6PD) activity in term and late preterm babies with severe neonatal hyperbilirubinemia and its relationship to the severity and treatment of this disorder, regardless of level of G6PD activity (deficient/normal).

METHODS

A total of 529 term and late preterm (≥35 weeks) infants (228 female, 301 male) who were diagnosed with severe hyperbilirubinemia were included in this study. In each case, serum was collected to evaluate blood group, direct Coombs' test, complete blood cell count, total and direct bilirubin, thyroid-stimulating hormone, and G6PD activity. A partial correlation analysis was carried out to assess the relationship between G6PD activity and total bilirubin levels.

RESULTS

A significant correlation was found between the severity of hyperbilirubinemia and G6PD activity in both males and females. Male neonates who had G6PD levels <12 U/g Hb required more phototherapy time than neonates who had G6PD levels ≥12 U/g Hb; and female neonates who had G6PD levels <16 U/g Hb required more phototherapy time than neonates who had G6PD levels ≥16 U/g Hb (p < 0.0001). When we analyzed only breastfed infants, a significant difference also emerged in both sexes. Decreased G6PD activity was associated with increased phototherapy time and the need for exchange transfusion.

CONCLUSION

Routine checks of G6PD level in hyperbilirubinemic neonates are very important in providing proper medical management to prevent bilirubin-induced neurological dysfunction. Appropriate identification of G6PD (<12 U/g Hb for male infants and <16 U/g Hb for female infants) raises awareness of the severity of the condition and the necessity for immediate care of severe hyperbilirubinemic infants.

Evaluation of neonatal jaundice in the Makkah region

The aims of this study were to detect the frequency at which the different types of neonatal jaundice occur in Makkah and to estimate the malondialdehyde (MDA) levels. This study included 239 neonates with neonatal jaundice, 20 anemic neonates and 21 healthy neonates. ABO incompatibility was observed in 31.6% of neonates with indirect hyperbilirubinemia, in 14.3% of those with early onset jaundice, in 9.5% of those with persistent jaundice, in 8.5% of those with physiological jaundice, in 5% of anemic neonates and in 12% of all neonates. glucose-6-phosphate dehydrogenase (G6PD) deficiency was observed in 10.5% of neonates with indirect hyperbilirubinemia, in 3.9% of those with physiological jaundice, in 11.1% of those with direct hyperbilirubinemia, in 12% of those with persistent jaundice, in 10% of anemic neonates and in 6.6% of all neonates. Rh incompatibility and polycythemia were found in 2.6% of neonates with indirect hyperbilirubinemia and in 0.4% of all neonates. In comparison to control group, MDA was significantly higher in all groups except for the anemic group. In conclusion, ABO incompatibility and G6PD deficiency frequently result in neonatal jaundice in Makkah, whereas Rh incompatibility and polycythemia are rare. The MDA level may serve as an indicator of oxidative stress.

PCR-based allelic discrimination for glucose-6-phosphate dehydrogenase (G6PD) deficiency in Ugandan umbilical cord blood

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common X-linked disorder in the world. G6PD deficiency puts children at risk for hyperbilirubinemia and kernicterus during the newborn period and an increased risk of severe hemolysis after exposure to many antimalarial medications. A laboratory diagnosis of G6PD deficiency is rare in the developing world due to limited resources. We developed a TaqMan-based allele-specific assay to rapidly determine rates of G6PD deficiency contributing alleles (G202A and A376G) in East Africa. We tested umbilical cord blood from 100 Ugandan newborns and found that the overall allele frequency of G202A was .13 and A376G was .32. The overall incidence of G6PD A- (G202A/A376G) was 6%; all A- variants were males. There was no correlation between G6PD deficiency and umbilical cord blood hemoglobin, white blood count, platelet count, or other hematologic parameters. Allele-specific PCR can serve as a rapid method to determine specific G6PD deficiency allele frequencies in a given population and as a diagnostic tool in a hospital setting in which laboratory resources are present.

Heme oxygenase-1 promoter polymorphisms and neonatal jaundice

BACKGROUND

Heme oxygenase (HO) is the initial, rate-limiting enzyme in the conversion of heme to bilirubin. Dinucleotide (GT)n repeat length in the promoter region of the encoding gene modulates transcription: shorter alleles, in contrast with longer allele counterparts, are associated with greater gene expression and should result in increased heme catabolism.

OBJECTIVE

We compared the rates of heme catabolism and plasma total bilirubin (TB) between HO-1 promoter genotypes of varying (GT)n repeat lengths in glucose-6-phosphate dehydrogenase (G6PD)-normal and -deficient neonates.

METHODS

HO-1 promoter length was determined from genomic DNA from previous studies by size discrimination of fluorescently-labeled PCR products with capillary electrophoresis. Sizing was confirmed by sequencing homozygote samples. Alleles were categorized as: short (≤24 GT repeats), medium (25-33 GT repeats), and long (≥34 GT repeats). Previously determined values for blood carboxyhemoglobin, corrected for inspired carbon monoxide (COHbc), and TB were used to determine the rate of heme catabolism and 3rd day TB values for each HO-1 promoter length genotype, respectively. G6PD Mediterranean was determined by PCR analysis.

RESULTS

Neither COHbc nor TB values were significantly different between various HO-1 promoter genotypes for either G6PD-normal or -deficient neonates.

CONCLUSIONS

In the steady state, HO-1 promoter genotypes, based on the length of (GT)n repeats, do not modulate heme catabolism or 3rd day TB values in either G6PD-normal or -deficient neonates.

Should we screen newborns for glucose-6-phosphate dehydrogenase deficiency in the United States?

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, a common X-linked enzymopathy can lead to severe hyperbilirubinemia, acute bilirubin encephalopathy and kernicterus in the United States. Neonatal testing for G6PD deficiency is not yet routine and the American Academy of Pediatrics recommends testing only in jaundiced newborns who are receiving phototherapy whose family history, ethnicity, or geographic origin suggest risk for the condition, or for infants whose response to phototherapy is poor. Screening tests for G6PD deficiency are available, are suitable for use in newborns and have been used in birth hospitals. However, US birth hospitals experience is limited and no national consensus has emerged regarding the need for newborn G6PD testing, its effectiveness or the best approach. Our review of current state of G6PD deficiency screening highlights research gaps and informs specific operational challenges to implement universal newborn G6PD testing concurrent to bilirubin screening in the United States.

Black race is not protective against hazardous bilirubin levels

Although black race is considered protective against hyperbilirubinemia, black infants appear at increased risk of kernicterus. We found that although black infants have a lower risk of developing total serum bilirubin levels ≥ 20 mg/dL than white infants, they appear at greater risk of developing levels ≥ 30 mg/dL.

Glucose-6-phosphate dehydrogenase deficiency and borderline deficiency: association with neonatal hyperbilirubinemia

OBJECTIVE

To characterize the occurrence of glucose-6-phosphate dehydrogenase (G6PD) deficiency and its association with neonatal hyperbilirubinemia.

STUDY DESIGN

This study involved an evaluation of G6PD data for 2656 newborns from a universal newborn screening program.

RESULTS

Mean G6PD activity was 14.2 ± 3.3 U/g Hb. Some 2.71% of the newborns were G6PD-deficient, and 1.77% had borderline G6PD activity, with male and female predominance, respectively. G6PD deficiency was more prevalent in newborns of Sephardic Jew and Muslim Arab backgrounds. The infants with G6PD deficiency had higher bilirubin levels at the time of discharge from the nursery. Infants with low and borderline G6PD activity were more likely to require phototherapy (22.2% and 25.5%, respectively, vs 7.6% of infants with normal G6PD activity; P < .005) and to have more referrals for exacerbation of jaundice (15.3% and 14.9%, respectively, vs 6.1%; P < .005). Mean G6PD activity was higher in preterm infants born at 27-34 weeks gestational age compared with those born later (16.3 ± 1.8 U/g Hb vs 14.8 ± 2.0 U/g Hb). Based on sex distribution and theoretical genetic calculations for the rate of heterozygous females, we propose that the range of borderline G6PD activity should be 2-10 U/g Hb rather than the currently accepted range of 2-7 U/g Hb.

CONCLUSIONS

There is association between G6PD deficiency and significant neonatal hyperbilirubinemia. Increased risk is also associated with borderline G6PD activity. The suggested new range for borderline G6PD activity should enhance the identification of females at risk. G6PD activity is higher in preterm infants.

Cardiovascular pharmacogenetics

Human genetic variation in the form of single nucleotide polymorphisms as well as more complex structural variations such as insertions, deletions and copy number variants, is partially responsible for the clinical variation seen in response to pharmacotherapeutic drugs. This affects the likelihood of experiencing adverse drug reactions and also of achieving therapeutic success. In this paper, we review key studies in cardiovascular pharmacogenetics that reveal genetic variations underlying the outcomes of drug treatment in cardiovascular disease. Examples of genetic associations with drug efficacy and toxicity are described, including the roles of genetic variability in pharmacokinetics (e.g. drug metabolizing enzymes) and pharmacodynamics (e.g. drug targets). These findings have functional implications that could lead to the development of genetic tests aimed at minimizing drug toxicity and optimizing drug efficacy in cardiovascular medicine.

Neonatal screening for glucose-6-phosphate dehydrogenase deficiency: biochemical versus genetic technologies

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, a commonly occurring genetic condition, is associated in neonates with severe hemolytic episodes, extreme hyperbilirubinemia, and bilirubin encephalopathy. Neonatal screening programs for the condition should increase parental and caretaker awareness, thereby facilitating early access to treatment with resultant diminished mortality and morbidity. However, screening for G-6-PD deficiency is not widely performed. Although G-6-PD-deficient males may be accurately identified, females are more difficult to categorize because many in this group may be heterozygotes with phenotype overlap between normal homozygotes, heterozygotes, and deficient homozygotes. Screening methodologies include biochemical qualitative assays, quantitative enzymatic activity measurements and DNA-based polymerase chain reaction molecular screening. The appropriateness of any of these technologies for any particular population group or geographic area must be assessed before setting up a screening program. The pros and cons of each method, including ease of testing, cost, need for sophisticated laboratory equipment and degree of personnel training, as well as the ability to identify females, are discussed.

Clinical and genetic risk factors for moderate hyperbilirubinemia in Brazilian newborn infants

OBJECTIVE

To identify clinical and genetic risk factors for moderate hyperbilirubinemia during the first week of life.

STUDY DESIGN

Using univariate and multivariate multiple regression analyses, the RR for clinical factors, the African variant of glucose-6-phosphate dehydrogenase (G6PD) deficiency (G202A/A376G), and (TA)(n) UGT1A1 polymorphisms were established in a cohort of 608 Brazilian newborn infants. Hyperbilirubinemia was monitored until 134.5 ± 49.8 h of life (IQR, 111.0 to 156.7). The dependent variable was total bilirubinemia (TB) ≥12.9 mg per 100 ml estimated by transcutaneous or plasma bilirubin measurements.

RESULT

The African variant of G6PD deficiency and (TA)(7)/(TA)(7) and (TA)(7)/(TA)(8) polymorphisms present in 6.1 and 12.0% of newborns, respectively, were not risk factors for moderate hyperbilirubinemia. Coexpression of G6DP deficiency and UGT1A1 polymorphisms occurred in 0.49% of the subjects. Independent clinical predictors for TB≥ 12.9 mg per 100 ml were gestational age <38 weeks and reference curve percentiles >P40th.

CONCLUSION

In this study, G6PD deficiency and UGT1A1 gene promoter polymorphisms were not risk factors for moderate hyperbilirubinemia. Genetic factors may vary considerably in importance among different populations.

Hemolysis and hyperbilirubinemia in antiglobulin positive, direct ABO blood group heterospecific neonates

OBJECTIVE

We quantified hemolysis and determined the incidence of hyperbilirubinemia in neonates who were direct antiglobulin titer (DAT)-positive, ABO heterospecific, and compared variables among O-A and O-B subgroups.

STUDY DESIGN

Plasma total bilirubin (PTB) was determined before the neonates were discharged from the hospital and more frequently when clinically warranted, in neonates who were DAT positive with blood group A or B and with mothers who had blood group O. Heme catabolism (and therefore bilirubin production) was indexed by blood carboxyhemoglobin corrected for inspired carbon monoxide (COHbc). Hyperbilirubinemia was defined as any PTB concentration >95th percentile on the hour-of-life-specific bilirubin nomogram.

RESULTS

Of 164 neonates, 111 were O-A and 53 O-B. Overall, hyperbilirubinemia developed 85 neonates (51.8%), and it tended to be more prevalent in the O-B neonates than O-A neonates (62.3% versus 46.8%; P = .053). Hyperbilirubinemia developed in more O-B newborns than O-A newborns at <24 hours (93.9% versus 48.1%; P< .0001). COHbc values were globally higher than our previously published newborn values. Babies in whom hyperbilirubinemia developed had higher COHbc values than the already high values of babies who were non-hyperbilirubinemic, and O-B newborns tended to have higher values than their O-A counterparts.

CONCLUSIONS

DAT-positive, ABO heterospecificity is associated with increased hemolysis and a high incidence of neonatal hyperbilirubinemia. O-B heterospecificity tends to confer even higher risk than O-A counterparts.

Glucose-6-phosphate dehydrogenase deficiency and severe neonatal hyperbilirubinemia: a complexity of interactions between genes and environment

Glucose-6-phosphate dehydrogenase deficiency is a commonly occurring genetic condition, likely to be encountered today in virtually any corner of the globe. Sudden episodes of hemolysis associated with the condition may result in exponential increases in serum total bilirubin concentrations to levels at which bilirubin-induced neurologic damage may occur. The hyperbilirubinemia is the result of complex interactions between genes and environment. Neonatal screening programs coupled with parental and medical caretaker education may be successful in limiting the severity of disease.

Hyperbilirubinemia in African American neonates: clinical issues and current challenges

African American neonates evidence a low incidence of hyperbilirubinemia yet account for more than 25% of the reported kernicterus cases in the USA. Glucose-6-phosphate dehydrogenase (G6PD) deficiency accounts for approximately 60%, and late preterm gestation and ABO hemolytic disease approximately 40% of these cases. Females heterozygous for G6PD A- harbor a population of G6PD-deficient red blood cells and are at risk for hyperbilirubinemia. Pre-discharge bilirubin measurement coupled with gestational age enhances the identification of neonates at hyperbilirubinemia risk. Parental education at the time of birth hospitalization discharge combined with timely follow-up may help to reduce the risk of developing hazardous hyperbilirubinemia.

Hepatitis B vaccination of male neonates and autism diagnosis, NHIS 1997-2002

Universal hepatitis B vaccination was recommended for U.S. newborns in 1991; however, safety findings are mixed. The association between hepatitis B vaccination of male neonates and parental report of autism diagnosis was determined. This cross-sectional study used weighted probability samples obtained from National Health Interview Survey 1997-2002 data sets. Vaccination status was determined from the vaccination record. Logistic regression was used to estimate the odds for autism diagnosis associated with neonatal hepatitis B vaccination among boys age 3-17 years, born before 1999, adjusted for race, maternal education, and two-parent household. Boys vaccinated as neonates had threefold greater odds for autism diagnosis compared to boys never vaccinated or vaccinated after the first month of life. Non-Hispanic white boys were 64% less likely to have autism diagnosis relative to nonwhite boys. Findings suggest that U.S. male neonates vaccinated with the hepatitis B vaccine prior to 1999 (from vaccination record) had a threefold higher risk for parental report of autism diagnosis compared to boys not vaccinated as neonates during that same time period. Nonwhite boys bore a greater risk.

Complex multifactorial nature of significant hyperbilirubinemia in neonates

OBJECTIVE

To determine whether glucose-6-phosphate dehydrogenase (G6PD), uridine-diphosphoglucuronosyltransferase 1A1 (UGT1A1), and hepatic solute carrier organic anion transporter 1B1 (SLCO1B1) gene variants occur at greater frequency in neonates with significant hyperbilirubinemia.

METHODS

Infants with gestational ages of >or=37 weeks and ages of <7 days were studied. Case subjects had >or=1 bilirubin level above the 95th percentile (high-risk zone), whereas control subjects had bilirubin levels of <40th percentile (low-risk zone) at study entry.

RESULTS

A total of 153 case subjects (median bilirubin level: 15.7 mg/dL) and 299 control subjects (median bilirubin level: 4.6 mg/dL) were evaluated. There were no statistical differences in the frequencies of G6PD, UGT1A1, and SCLO1B1 gene variants between case and control subjects (G6PD: 5.2% vs 3.3%; UGT1A1: 14.4% vs 9.4%; SLCO1B1: 73.2% vs 73.6%). However, coexpression of the G6PD African A- mutation with UGT1A1 and/or SLCO1B1 variants was seen more frequently for case subjects. Case subjects more often demonstrated >or=2 factors contributing to hyperbilirubinemia, including ABO blood group heterospecificity in which the mother had blood group O (47.7% vs 11.4%), positive direct Coombs test results (33.3% vs 4%), sibling treated with phototherapy (16.3% vs 5.4%), maternal circulating blood group antibodies (10.5 vs 0.7%), maternal diabetes mellitus (13.1% vs 6.4%), and maternal East Asian ethnicity (6.5% vs 1.3%).

CONCLUSIONS

Clinical contributors to hyperbilirubinemia were identified more frequently for case subjects but individually G6PD, UGT1A1, and SLCO1B1 variants were not. Coexpression of the G6PD African A- mutation with UGT1A1 and SLCO1B1 variants was seen more often for case subjects.

Neonatal hyperbilirubinemia and kernicterus - not gone but sometimes forgotten

The introduction of exchange transfusion made it possible to prevent severe hyperbilirubinemia and kernicterus, but kernicterus has never completely disappeared and it is still occurring in North America and, more frequently in Western Europe and the developing world. I discuss the epidemiology and major causes of severe hyperbilirubinemia and the potential root causes and system failures associated with the development of extreme hyperbilirubinemia and, subsequently, kernicterus. In the Western world, kernicterus remains a rare cause of cerebral palsy but, in contrast to the other causes of cerebral palsy, kernicterus should almost always be preventable. The key elements in preventing kernicterus are risk assessment and appropriate follow-up for the newborn infant and these are presented in a recently developed algorithm. Implementation of this approach might contribute to the prevention of severe hyperbilirubinemia and bilirubin encephalopathy.

Identification of neonates at risk for hazardous hyperbilirubinemia: emerging clinical insights

Hyperbilirubinemia is the most common condition requiring evaluation and treatment in neonates. Identifying among all newborns those few at risk to develop marked hyperbilirubinemia is a clinical challenge. Clinical, epidemiologic, and genetic risk factors associated with severe hyperbilirubinemia include late preterm gestational age, exclusive breastfeeding, glucose-6-phosphate dehydrogenase deficiency, ABO hemolytic disease, East Asian ethnicity, jaundice observed in the first 24 hours of life, cephalohematoma or significant bruising, and history of a previous sibling treated with phototherapy. It is increasingly apparent that the etiopathogenesis of severe hyperbilirubinemia is often multifactorial, and emerging evidence suggests that combining risk factor assessment with measurement of predischarge total serum or transcutaneous bilirubin levels will improve hyperbilirubinemia risk prediction.

Exchange transfusion for neonatal hyperbilirubinemia with glucose-6-phosphate-deficient blood

Evaluation of: Samanta S, Kumar P, Kishore SS, Garewal G, Narang A: Donor blood glucose-6-phosphate dehydrogenase deficiency reduces the efficacy of exchange transfusion in neonatal hyperbilirubinemia. Pediatrics 123, E96–E100 (2009). Intravascular hemolysis following transfusion with glucose-6-phosphate dehydrogenase (G-6-PD)-deficient blood has been documented, although it is not routine to screen donor blood for this condition prior to exchange transfusion. Samanta et al. studied the effect of exchange transfusion with G-6-PD-deficient donor blood on neonates with moderate hyperbilirubinemia to determine the effectiveness of the exchange, postexchange serum total bilirubin levels, the duration of phototherapy and the need for repeat exchange transfusion. A total of 21 newborns were exchanged with G-6-PD-deficient donor blood and 114 with G-6-PD normal blood. Although the percentage decrease in serum total bilirubin from pre-exchange values immediately following the exchange was similar between the groups, during the postexchange period the percentage decrease became less in those exchanged with G-6-PD-deficient blood. Similarly, the duration of postexchange phototherapy and the number of babies requiring repeat exchange transfusion, were higher in those transfused with G-6-PD-deficient blood. The authors recommend that in areas where G-6-PD deficiency is prevalent, donor blood should be screened for G-6-PD deficiency prior to exchange transfusion use.

The need for neonatal glucose-6-phosphate dehydrogenase screening: a global perspective

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is an important cause of severe neonatal hyperbilirubinemia, and is overrepresented, even in countries with a low overall incidence of the enzyme deficiency, in the etiology of kernicterus. Neonatal screening for G-6-PD deficiency before discharge from the birth hospitalization should be instrumental in increasing parental and medical caretaker awareness of the high-risk nature of an infant, thereby effecting earlier referral of hyperbilirubinemic neonates for medical evaluation and treatment. The need for global screening, timing of screening, and the pros and cons of biochemical versus molecular DNA screening were discussed at the Newborn Jaundice and Kernicterus Meeting in Siena. The participants agreed that there was a need to expand neonatal G-6-PD screening globally and that screening results should be obtained before the infants' discharge from birth hospitalization.

(TA)n UDP-glucuronosyltransferase 1A1 promoter polymorphism in Nigerian neonates

Nigerian neonates have a high incidence of bilirubin encephalopathy. Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is prevalent in this population. (TA)7 promoter polymorphism in the gene encoding the bilirubin conjugating enzyme UDP-glucuronosyltransferase 1A1 (UGT1A1) potentiates hyperbilirubinemia in G-6-PD deficient neonates. We studied (TA)n allele frequency to determine, at least in part, its contribution to the frequency and severity of hyperbilirubinemia. DNA was extracted from umbilical cord blood of sequentially born Nigerian neonates and the (TA)n UGT1A1 promoter sequence determined. The (TA)n allele distribution was compared with reported adults of varying African ancestry and Sephardic Jewish neonates. Among 88 Nigerian neonates, (TA)6 and (TA)7 alleles were almost equally distributed (0.46 and 0.43, respectively). Some individuals with (TA)5 and (TA)8 sequences were encountered. Allele distribution was similar to that of the African ancestry population but differed from the Sephardic Jewish newborns, in whom the (TA)6/(TA)7 distribution was 0.65/0.35. Whereas 45% of Nigerian alleles and 50% of African ancestry alleles, respectively, included a (TA)7 or (TA)8 sequence, only 35% of Jewish alleles were (TA)7 (p < 0.001), and no (TA)8 alleles were encountered. The high frequency of (TA)n promoter polymorphism, coupled with G-6-PD deficiency, may contribute to the pathogenesis of extreme neonatal hyperbilirubinemia in Nigeria.

A comparison of alternative risk-assessment strategies for predicting significant neonatal hyperbilirubinemia in term and near-term infants

OBJECTIVE

The purpose of this work was to compare the predictive accuracy of alternative risk-assessment strategies used to screen for the risk of significant neonatal hyperbilirubinemia.

PATIENTS AND METHODS

We conducted a prospective cohort study of 823 term and near-term newborns admitted to the well-infant nursery at the Hospital of the University of Pennsylvania. Maternal, infant, and delivery risk factors for significant hyperbilirubinemia were obtained from chart review, structured interviews with parents, and nurse assessments before discharge. Transcutaneous bilirubin measurement was performed daily until discharge and once by a visiting home nurse between 3 and 8 days of life. We used the c statistic to compare the predictive accuracy of 3 risk-assessment strategies for estimating the risk of significant neonatal hyperbilirubinemia, defined as a bilirubin level that at any time after birth exceeded or was within 1 mg/dL (17 micromol/L) of the hour-specific phototherapy treatment threshold recommended by the American Academy of Pediatrics in 2004. The compared strategies included those that use (1) a predischarge bilirubin level (obtained before 52 hours) expressed as a risk zone on an hour-specific bilirubin nomogram, (2) clinical risk factors other than the predischarge bilirubin level, and (3) a combination of the predischarge bilirubin risk zone and additional clinical risk factors.

RESULTS

Forty-eight patients (6%) developed significant neonatal hyperbilirubinemia. The predischarge (<52 hours) bilirubin level expressed as a risk zone on the bilirubin nomogram and a prediction model that combined multiple other clinical risk factors had similar accuracy for predicting significant hyperbilirubinemia. The only clinical risk factor that could be added to the predischarge risk zone to improve overall predictive accuracy was gestational age. The predischarge bilirubin risk zone and gestational age could be used to stratify patients into a large group (n = 523 [70%]) of infants with a very low (0.2%) risk of developing significant hyperbilirubinemia, a small group of infants (n = 127 [17%]) with a low (4%) risk of developing significant hyperbilirubinemia, and an even smaller group of infants (n = 100 [13%]) with a high (42%) risk of developing significant hyperbilirubinemia.

CONCLUSIONS

An infant's risk of developing significant hyperbilirubinemia can be simply and accurately assessed by using just the infant's predischarge bilirubin level and gestational age.

Three mutations analysis of glucose-6-phosphate dehydrogenase deficiency in neonates in South-west China

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, one of the most common human enzymatic defects, is characterized by extreme molecular and biochemical heterogeneity. The underlying DNA changes associated with G6PD deficiency in Asian subjects have not been extensively investigated.

METHODS

Three gene mutations (G1388A, G1376T, A95G, corresponding amino acid change: Arg463His, Arg459Leu, His32Arg, respectively) were examined in 240 G6PD-deficient subjects originating from South-west China using specific polymerase chain reaction.

RESULTS

Of the 240 patients with G6PD deficiency, 190 were found to have the G1388A mutation, 48 had G1376T and two had A95G. There were no significant differences between the clinical manifestations caused by the former two gene mutations, which both cause acute hemolytic anemia and jaundice. Therefore the most common gene mutations of G6PD deficiency in neonates in South-west China are G1388A and G1376T mutations.

CONCLUSION

It is suggested that G6PD deficiency screening be done in higher risk neonates with jaundice in qualified hospitals as soon as possible.

(TA)n UGT 1A1 promoter polymorphism: a crucial factor in the pathophysiology of jaundice in G-6-PD deficient neonates

Increased heme catabolism has been reported in glucose-6-phosphate dehydrogenase (G-6-PD)-normal neonates who were also homozygous for (TA)7/(TA)7 (UGT1A1*28) uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT) promoter polymorphism (Gilbert syndrome). As G-6-PD deficiency is associated with increased hemolysis, we hypothesized that in G-6-PD-deficient neonates who also have the (TA)7/(TA)7 UGT promoter genotype, steady-state hemolysis would be even further increased. Male G-6-PD-deficient neonates were sampled for plasma total bilirubin (PTB), blood carboxyhemoglobin corrected for inhaled carbon monoxide in ambient air (COHbc) (an index of heme catabolism), and UGT (TA)n promoter genotype determination and compared with previously published G-6-PD-normal neonates. Although COHbc values were higher in the G-6-PD-deficient than in the G-6-PD-normal cohorts (0.97 +/- 0.32% of total Hb (tHb) versus 0.76 +/- 0.19% of tHb, p < 0.001), PTB values were similar (9.2 +/- 3.4 mg/dL versus 8.9 +/- 3.0 mg/dL, respectively, p = 0.3). Within the G-6-PD-deficient group, although COHbc values were alike between the three UGT promoter genotypes, PTB was higher in the (TA)7/(TA)7 homozygotes (11.1 +/- 4.0 mg/dL) compared with (TA)6/(TA)7 heterozygotes (9.1 +/- 3.2 mg/dL, p = 0.03) and wild-type (TA)6/(TA)6 homozygotes (8.8 +/- 3.4 mg/dL, p = 0.02). In the steady state, similar rates of hemolysis, but increased PTB in the G-6-PD- deficient, (TA)7/(TA)7 homozygotes, imply that (TA)7/(TA)7, homozygosity is central to increased PTB.

Neonatal hyperbilirubinemia in African American males: the importance of glucose-6-phosphate dehydrogenase deficiency

OBJECTIVE

To perform risk factor analysis for the prediction of hyperbilirubinemia in an African American male neonatal cohort.

STUDY DESIGN

A database of 500 previously published term and near-term African American male neonates was further analyzed to determine the role of risk factors for hyperbilirubinemia. Factors studied included birth weight >/=4.0 kg, gestational age /=75(th) percentile. Hyperbilirubinemia was defined as any bilirubin value >/=95(th) percentile on the hour-of-life-specific bilirubin nomogram.

RESULTS

Forty-three (8.6%) neonates developed hyperbilirubinemia. At 48 +/- 12 hours, median transcutaneous bilirubin was 8.3 mg/dL, 75(th) percentile 10.0 mg/dL, and 95(th) percentile 12.6 mg/dL. Of the risk factors, only exclusive breast-feeding, G-6-PD deficiency and predischarge bilirubin >/=75(th) percentile were significant (Adjusted Odds Ratios [95% Confidence Intervals; CI] 3.15 [1.39-7.14], P = .006; 4.96 [2.28-10.80], P = .001; and 7.47 [3.50-15.94], P < .0001, respectively). G-6-PD-deficient neonates who were also premature and breast-feeding had the highest incidence of hyperbilirubinemia (60%).

CONCLUSIONS

African American male neonates may be at higher risk for hyperbilirubinemia than previously thought. Screening for G-6-PD deficiency and predischarge bilirubin determination may be useful adjuncts in hyperbilirubinemia prediction in these newborns.