Gilbert or Crigler-Najjar syndrome? Neonatal severe unconjugated hyperbilirubinemia with P364L UGT1A1 homozygosity.

BACKGROUND: Several mutations of bilirubin uridine diphosphate-glucuronosyltransferase gene (UGT1A1) have been reported in patients with unconjugated hyperbilirubinemia. Few reports are available about the p.Pro364Leu mutation (P364L, c.1091C > T) in homozygous newborns. We describe the clinical, laboratory and therapeutic approach in two Chinese neonates with severe jaundice, homozygous for the P364L mutation. CASE PRESENTATION: Two Chinese breastfed female infants presented prolonged unconjugated hyperbilirubinemia at the age of 1 month. Total bilirubin was higher than 15 mg/dl (D < 1). An exhaustive etiological work-up to detect possible causes of hyperbilirubinemia (notably hemolytic ones) was negative. The promoter and coding regions of UGT1A1 were amplified by polymerase chain reaction (PCR) from genomic DNA isolated from leukocytes. Both patients resulted homozygous for a variant site within the coding region of the gene in the 4 exon, c.1091C > T, p.Pro364Leu. In front of the persistently high level of unconjugated bilirubin, phototherapy was performed without persistent results. A treatment with phenobarbital was then begun and bilirubin level progressively decreased, with a complete and persistent normalization. The therapy was stopped. CONCLUSION: UGT1A1 enzyme activity associated with the P364L mutation has been described as 35.6% of the wild-type enzyme activity. Photo-therapy and phenobarbital can be useful in front of persistently high level of unconjugated bilirubin. Our cases presented high bilirubin values, overlapping between Gilbert syndrome (GS) and Crigler-Najjar syndrome type II (CNS), but the complete normalization of bilirubin makes GS more likely. Homozygous P364L variant can be associated with severe neonatal unconjugated hyperbilirubinemia in Chinese infants, but jaundice can completely resolve in a few months, contrary to what happens in Crigler-Najjar syndrome type II.

Genetic Factors and Delayed TSB Monitoring and Treatment as Risk Factors Associated with Severe Hyperbilirubinemia in Term Neonates Admitted for Phototherapy.

OBJECTIVES: This study aimed to determine whether maternal-fetal blood group isoimmunization, breastfeeding, birth trauma, age when first total serum bilirubin (TSB) was measured, age of admission, and genetic predispositions to hemolysis [due to genetic variants of glucose-6-phosphate dehydrogenase (G6PD) enzyme], and reduced hepatic uptake and/or conjugation of serum bilirubin [due to genetic variants of solute carrier organic anion transporter protein family member 1B1 (SLCO1B1) and uridine diphosphate glucuronosyltransferase family 1 member A1 (UGT1A1)] were significant risk factors associated with severe neonatal hyperbilirubinemia (SNH, TSB ≥ 342µmol/l) in jaundiced term neonates admitted for phototherapy. METHODS: The inclusion criteria were normal term neonates (gestation ≥ 37 weeks). Parents/care-givers were interviewed to obtain data on demography, clinical problems, feeding practice and age when first TSB was measured. Polymerase chain reaction-restriction fragment length polymorphism method was used to detect common G6PD, UGT1A1 and SLCO1B1 variants on each neonate's dry blood specimens. RESULTS: Of 1121 jaundiced neonates recruited, 232 had SNH. Logistic regression analysis showed that age (in days) when first TSB was measured [adjusted odds ratio (aOR) = 1.395; 95% confidence interval (CI) 1.094-1.779], age (in days) of admission (aOR = 1.127; 95% CI 1.007-1.260) and genetic mutant UGT1A1 promoter A(TA)7TAA (aOR = 4.900; 95% CI 3.103-7.739), UGT1A1 c.686C>A (aOR = 6.095; 95% CI 1.549-23.985), SLCO1B1 c.388G>A (aOR = 1.807; 95% CI 1.242-2.629) and G6PD variants and/or abnormal G6PD screening test (aOR = 2.077; 95% CI 1.025-4.209) were significantly associated with SNH. CONCLUSION: Genetic predisposition, and delayed measuring first TSB and commencing phototherapy increased risk of SNH.

Identification of Genetic Risk Factors for Neonatal Hyperbilirubinemia in Fujian Province, Southeastern China: A Case-Control Study.

To date, the genetic risk factors for neonatal hyperbilirubinemia remain unknown in Southeastern China. This case-control study aimed to identify the genetic risk factors for neonatal hyperbilirubinemia in Fujian, Southeastern China. A total of 286 hyperbilirubinemic newborns were enrolled as a case group, and 250 randomly selected newborns without jaundice or with a bilirubin level that was lower than the threshold required for phototherapy served as controls. The serum levels of total bilirubin, unconjugated bilirubin, and direct bilirubin were measured, and the common genetic loci in UGT1A1, OATP1B1, and HO-1 genes were genotyped. Higher incidence of ABO incompatibility and G6PD deficiency was detected in the case group compared to the control group (P < 0.01). There were significant differences in the frequencies of rs4148323 and rs1805173 genotypes between the case and control groups (P < 0.05). At the rs4148323 locus, the frequencies of GA heterozygotes and AA mutant homozygotes were higher in the case group than in the control group (P < 0.05), and at the rs1805173 locus, the frequencies of LS, MS, and SS genotypes were higher in the case group than in the control group (P < 0.05). A higher frequency of rs4148323 A allele and rs1805173 S allele was detected in the case group compared to the control group (P = 0). Additionally, multivariate logistic regression analysis identified that the mutant genotype of rs4148323 in the UGT1A1 gene, ABO incompatibility, G6PD deficiency, and SS genotype at rs1805173 locus of the HO-1 gene were genetic risk factors of neonatal hyperbilirubinemia. Our data demonstrate that G211 mutation in the UGT1A1 gene, ABO incompatibility, G6PD deficiency, and the SS genotype of the repeats in the promoter region of the HO-1 gene are risk factors for neonatal hyperbilirubinemia in Fujian, Southeastern China.

Heme oxygenase-1 genetic variants and the conundrum of hyperbilirubinemia in African-American newborns.

BACKGROUND: African-American (AA) infants are known to have, overall, lower bilirubin levels than infants of other ethnicities during their birth hospitalization. However, they are known to have a higher incidence of severe hyperbilirubinemia and are over represented in the US Kernicterus Registry. Heme oxygenase-1 (HO) is the rate limiting enzyme in heme metabolism leading to the equimolar production of bilirubin, carbon monoxide (CO) and free iron (Fe). Short (S) (GT)n repeats (<25) in the promoter region of the gene encoding the inducible HO-1 isozyme augment its expression, while long (L) repeats (>33) lead to an attenuation, modulating the production of bilirubin and CO. The impact of HO-1 promoter polymorphisms on bilirubin levels has not been well studied in (AA) infants. OBJECTIVE: The objectives of this study were to compare the distribution of (GT)n repeat lengths in the HO-1 promoter region in a cohort of AA infants to those found in other ethnicities and to evaluate the contribution of this polymorphism to the degree of hyperbilirubinemia and the level of COHbc in this cohort. METHODS: We prospectively studied a cohort of term AA infants with O+ mothers. Per hospital routine, infants' blood type, Rh status, direct antiglobulin test (DAT), and total bilirubin (TB) levels were checked prior to discharge. After parental consent, blood was collected for DNA extraction and carboxyhemoglobin (COHbc) measurements at the same time as the infants' newborn screen. An infant's TB percentile risk based on the Bhutani nomogram was used to determine need for phototherapy or follow-up. (GT)n repeat length in the HO-1 promoter was determined for each allele using PCR after DNA extraction from dried bloodspots. Size of allele lengths were typed as short (S, <25), medium (M, 25-33) or long (L, >33). RESULTS: One hundred eighty infants were studied for a total of 360 separate alleles. 12.2% (44/360) of alleles were S which was significantly less than all other ethnicities reviewed. Carboxyhemoglobin (COHbc) levels and bilirubin percentiles were higher among infants who had at least one S allele when compared to those who had at least one L allele in the cohort as a whole: COHbc 0.92 ± 0.35 vs. 0.85 ± 0.37; p = 0.28 and Bilirubin percentile 48.6 ± 34.0 vs. 44.9 ± 31.6; p = 0.51. This relationship remained when only those infants who were DAT neg were examined: COHbc 0.81 ± 0.26 vs. 0.74 ± 0.21; p = 0.11 and Bilirubin percentile 43.6 ± 29.9 vs. 37.5 ± 28.7; p = 0.28. CONCLUSIONS: The presence of L alleles of this variant is significantly greater among infants who are either African or of African descent. There was a trend toward lower COHbc levels among infants with at least one L allele as opposed to at least one S allele, although this did not have a statistically significant impact on TB risk percentile.

Prolonged indirect hyperbilirubinemia in a moderately preterm boy with Mediterranean glucose-6-phosphate dehydrogenase and glutathione S-transferase Mu 1 null mutations.

A 33-week gestation boy with Mediterranean glucose-6-phosphate dehydrogenase (G6PD) and a glutathione S-transferase Mu 1 null mutations (GSTM1*0/*0) developed prolonged indirect hyperbilirubinemia (PIH). He had no laboratory evidence of haemolysis or infection, and no exposure to oxidising agents. He has two full-term older brothers who have no history of neonatal hyperbilirubinemia. One brother, who was exclusively breast fed, has only Mediterranean G6PD and the other has only GSTM1*0/*0. The three boys have no mutation in the uridine diphosphate glucuronosyltransferase 1A1 gene. This suggests that a combination of all or any two of prematurity, G6PD deficiency and GSTM1*0/*0 is a possible risk factor for PIH. However, this remains to be confirmed.

Influence of hyperbilirubinemia and phototherapy on markers of genotoxicity and apoptosis in full-term infants.

UNLABELLED: Concerns of possible genotoxic effects of hyperbilirubinemia and phototherapy were raised from experimental and observational studies in neonates. This study aimed to assess the impact of hyperbilirubinemia and phototherapy on DNA damage and apoptosis in peripheral blood lymphocytes in healthy full-term infants. This study was conducted in the Children's Hospital, Mansoura University. Patients enrolled in this study were classified into three groups (each with 45 full-term infants): group 1 was composed of infants with hyperbilirubinemia requiring phototherapy, group 2 infants with physiological jaundice not requiring phototherapy, and group 3 infants without clinical jaundice. All enrolled infants were subjected to assessment of DNA damage and apoptosis in peripheral blood lymphocytes, using the comet assay and P53 by flow cytometry, consecutively. In group 1, measurements were done twice, before starting phototherapy and just before its discontinuation. DNA damage was not significantly different in the three groups, but it significantly increased after exposure to phototherapy compared to pre-phototherapy levels. There was no significant difference in P53 level in the three groups; however, it significantly increased after exposure to phototherapy. There were significant positive correlations between the duration of phototherapy and markers of DNA damage and apoptosis. CONCLUSIONS: Hyperbilirubinemia does not influence DNA damage and apoptosis, whereas phototherapy causes DNA damage and induces apoptosis in peripheral blood lymphocytes of full-term infants.

Combined effects of the UGT1A1 and OATP2 gene polymorphisms as major risk factor for unconjugated hyperbilirubinemia in Indian neonates.

Genetic association studies have linked a number of single nucleotide polymorphisms (SNPs) with unconjugated hyperbilirubinemia. The present study was undertaken to validate the association of SNPs with development of hyperbilirubinemia in Indian neonates. Genotyping of five SNPs in two candidate genes was performed in 126 infants with hyperbilirubinemia and 181 controls by PCR-RFLP, Gene Scan analysis and direct DNA sequencing. Genetic polymorphisms of the UGT1A1 promoter, specifically the -3279 T➔G phenobarbital responsive enhancer module (rs4124874) and (TA)7 dinucleotide repeat (rs8175347) as well as the coding region variants (rs2306283 and rs4149056) of the OATP2 gene were significantly higher among the cases than the controls. The presence of the mutant haplotypes either in homozygous, heterozygous or compound heterozygous state had a significant effect on neonatal hyperbilirubinemia as well as on the requirement of phototherapy than those with the wild haplotype. Further, a significantly higher number of hyperbilirubinemic cases had ≥3 variants than the controls (73.80% vs 40.36%, p<0.0001) and the mean total serum bilirubin levels and requirement of phototherapy also increased according to the number of variants co-expressed. This study demonstrates that UGT1A1 and OATP2 polymorphisms were associated with altered bilirubin metabolism and could be genetic risk factors for neonatal hyperbilirubinemia.

UGT1A1 gene variants and clinical risk factors modulate hyperbilirubinemia risk in newborns.

OBJECTIVE: To study the contribution of UGT1A1 gene variants and clinical risk factors in modulating hyperbilirubinemia risk in newborns. STUDY DESIGN: Seven UGT1A1 gene variants and clinical risk factors were studied in 113 hyperbilirubinemia cases and 218 control newborns. Hyperbilirubinemia was defined as the total serum bilirubin levels >95th percentile of the American Academy of Pediatrics nomogram. The study population included term (37 to 41 weeks) newborns below 2 weeks of age. RESULT: UGT1A1 gene variants, namely, c.211G>A, g.-3279T>G, TATA box polymorphism and CAT insertion were identified as independent molecular risk factors for neonatal hyperbilirubinemia, whereas c.686C>A, c.1091C>T and c.1456T>G were not detected in study cohort. Among clinical risk factors, excessive weight loss, sepsis and ABO incompatibility emerged as independent risk factors. Co-expression of UGT1A1 variants and clinical risk factors further accentuated the risk of neonatal hyperbilirubinemia. CONCLUSION: Multiple risk factors, whether genetic or clinical, are instrumental in modulating hyperbilirubinemia risk in newborns. Disordered bilirubin conjugation through interactions of UG1TA1 gene variants contributes to the clinical phenotype of neonatal hyperbilirubinemia.

Neonatal hyperbilirubinemia in infants with G6PD c.563C > T Variant.

BACKGROUND: There is a strong correlation between glucose-6-phosphate dehydrogenase (G6PD) deficiency and neonatal hyperbilirubinemia with a rare but potential threat of devastating acute bilirubin encephalopathy. G6PD deficiency was observed in 4-14% of hospitalized icteric neonates in Pakistan. G6PD c.563C > T is the most frequently reported variant in this population. The present study was aimed at evaluating the time to onset of hyperbilirubinemia and the postnatal bilirubin trajectory in infants having G6PD c.563C > T. METHODS: This was a case-control study conducted at The Aga Khan University, Pakistan during the year 2008. We studied 216 icteric male neonates who were re-admitted for phototherapy during the study period. No selection was exercised. Medical records showed that 32 were G6PD deficient while 184 were G6PD normal. Each infant was studied for birth weight, gestational age, age at the time of presentation, presence of cephalhematoma, sepsis and neurological signs, peak bilirubin level, age at peak bilirubin level, days of hospitalization, whether phototherapy or exchange blood transfusion was initiated, and the outcome. During hospital stay, each baby was tested for complete blood count, reticulocyte count, ABO and Rh blood type, direct antiglobulin test and quantitative G6PD estimation [by kinetic determination of G6PDH]. G6PDgenotype was analyzed in 32 deficient infants through PCR-RFLP analysis and gene sequencing. RESULTS: G6PD variants c.563C > T and c.131 C > G were observed in 21 (65%) and three (9%) of the 32 G6PD deficient infants, respectively. DNA of eight (25%) newborns remained uncharacterized. In contrast to G6PD normal neonates, infants with c.563C > T variant had significantly lower enzyme activity (mean ± 1SD; 0.3 ± 0.2 U/gHb vs. 14.0 ± 4.5 U/gHb, p < 0.001) experienced higher peak levels of total serum bilirubin (mean ± 1SD; 16.8 ± 5.4 mg/dl vs. 13.8 ± 4.6 mg/dl, p = 0.008) which peaked earlier after birth (mean ± 1SD 2.9 ± 1.6 vs. 4.3 ± 2.3 days, p = 0.007). No statistically significant difference was observed in mean weight, age at presentation, hemoglobin, reticulocyte count, TSH level, hospital stay or in the frequency of initiation of phototherapy or blood exchange between the two groups. CONCLUSIONS: We concluded that infants with G6PD c.563C > T variant developed jaundice earlier than infants with normal G6PD enzyme levels. Compared to G6PD normal infants, G6PD c.563C > T carrying infants had significantly low G6PD activity.

UGT1A1, SLCO1B1, and SLCO1B3 polymorphisms vs. neonatal hyperbilirubinemia: is there an association?

BACKGROUND: Jaundice is a physiological phenomenon; however, severe hyperbilirubinemia occurs in only 5 to 6% of the healthy newborn population. It has been suggested that genetic variation could enhance the risk of hyperbilirubinemia when coexpressed with other icterogenic conditions. METHODS: The study included newborns with a gestational age of greater than 35 wk and weights greater than 2,000 g with indications for phototherapy. The polymorphisms from UGT1A1 (rs8175347), SLCO1B1 (rs4149056 and rs2306283), and SLCO1B3 (rs17680137 and rs2117032) were analyzed by capillary electrophoresis and hydrolysis probes. RESULTS: A total of 167 hyperbilirubinemic infants and 247 control subjects were enrolled. The gender, ABO incompatibility, birth weight, and gestational age differed between the groups, but the allelic and genotypic frequency of the polymorphisms from SLCO1B genes did not. In logistic regression, the ABO incompatibility, gestational age, and polymorphic T allele of rs2117032 remained in the model. The presence of this polymorphism seemed to provide protection from hyperbilirubinemia. The individuals who were homozygous for the G allele of rs2306283 and who were glucose 6-phosphate-dehydrogenase deficient were more frequent among the cases. CONCLUSION: Although genetic variation accounts for a good part of this condition, the association between different polymorphisms and environmental factors has yet to be explained.

211 G to a variation of UDP-glucuronosyl transferase 1A1 gene and neonatal breastfeeding jaundice.

Breastfeeding jaundice is a common problem in neonates who were exclusively breastfed, but its pathogenesis is still unclear. The uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1) gene polymorphism was shown to contribute to the development of neonatal hyperbilirubinemia. We hypothesize that the variation of UGT1A1 gene may contribute to neonatal breastfeeding jaundice. We prospectively enrolled 688 near-term and term infants who were exclusively breastfed (BF group) or were supplemented by infant formula partially (SF group) before onset of hyperbilirubinemia. Genotyping of the promoter and exon1 of UGT1A1 was performed in all neonates. Neonates in BF group had a significantly higher maximal body weight loss ratio, peak bilirubin level, and a greater incidence of hyperbilirubinemia than those in SF group. Neonates with nucleotide 211 GA or AA variation in UGT1A1 genotypes had higher peak serum bilirubin levels and higher incidence of hyperbilirubinemia than WTs (GG). This phenomenon was only seen in BF group but not in SF group when subset analysis was performed. This suggests that neonates who carry the nucleotide 211 GA or AA variation within coding region in UGT1A1 gene are more susceptible to develop early-onset neonatal breastfeeding jaundice.

Hiperbilirrubinemia neonatal agravada / Aggravated neonatal hyperbilirubinemia

INTRODUCCIÓN. La mayoría de las veces la ictericia en el recién nacido es un hecho fisiológico, causado por una hiperbilirrubinemia de predominio indirecto, secundario a inmadurez hepática e hiperproducción de bilirrubina. El objetivo de este estudio fue determinar el comportamiento de la hiperbilirrubinemia neonatal en el Hospital Docente Ginecoobstétrico de Guanabacoa en los años 2007 a 2009. MÉTODOS. Se realizó un estudio descriptivo y retrospectivo de 173 recién nacidos que ingresaron al Departamento de Neonatología con diagnóstico de hiperbilirrubinemia agravada. RESULTADOS. La incidencia de hiperbilirrubinemia neonatal agravada fue del 3,67 por ciento y predominó en hermanos con antecedentes de ictericia (56,65 por ciento). El tiempo de aparición fue de 48 a 72 h (76,87 por ciento) y entre los factores agravantes se hallaron el nacimiento pretérmino y el bajo peso al nacer. La mayoría de los pacientes fueron tratados con luminoterapia (90,17 por ciento). CONCLUSIËN. La hiperbilirrubinemia neonatal agravada constituye un problema de salud. Los factores agravantes son la prematuridad y el bajo peso al nacer. La luminoterapia es una medida terapéutica eficaz para su tratamiento (AU)

INTRODUCTION. Most of times jaundice in newborn is a physiological fact due to hyperbilirubinemia of indirect predominance, secondary to liver immaturity and to bilirubin hyperproduction. The aim of present of present study was to determine the behavior of neonatal hyperbilirubinemia in the Gynecology and Obstetrics Teaching Hospital of Guanabacoa municipality from 2007 to 2009. METHODS. A retrospective and descriptive study was conducted in 173 newborn patients admitted in the Neonatology Department diagnosed with severe hyperbilirubinemia. RESULTS. The incidence of severe neonatal hyperbilirubinemia was of 3,67 percent with predominance in brothers with a history of jaundice (56,65 percent). The time of appearance was of 48 to 72 hrs (76,87 percent) and among the aggravating factors were the preterm birth and a low birth weight. Most of patients were treated with luminotherapy (90,17 percent). CONCLUSION. The severe neonatal hyperbilirubinemia is a health problem. Aggravating factors include the prematurity and the low birth weight. Luminotherapy is an effective therapeutic measure for its treatment (AU)

Hiperbilirrubinemia neonatal agravada / Aggravated neonatal hyperbilirubinemia

INTRODUCCIÓN. La mayoría de las veces la ictericia en el recién nacido es un hecho fisiológico, causado por una hiperbilirrubinemia de predominio indirecto, secundario a inmadurez hepática e hiperproducción de bilirrubina. El objetivo de este estudio fue determinar el comportamiento de la hiperbilirrubinemia neonatal en el Hospital Docente Ginecoobstétrico de Guanabacoa en los años 2007 a 2009. MÉTODOS. Se realizó un estudio descriptivo y retrospectivo de 173 recién nacidos que ingresaron al Departamento de Neonatología con diagnóstico de hiperbilirrubinemia agravada. RESULTADOS. La incidencia de hiperbilirrubinemia neonatal agravada fue del 3,67 por ciento y predominó en hermanos con antecedentes de ictericia (56,65 por ciento). El tiempo de aparición fue de 48 a 72 h (76,87 por ciento) y entre los factores agravantes se hallaron el nacimiento pretérmino y el bajo peso al nacer. La mayoría de los pacientes fueron tratados con luminoterapia (90,17 por ciento). CONCLUSIËN. La hiperbilirrubinemia neonatal agravada constituye un problema de salud. Los factores agravantes son la prematuridad y el bajo peso al nacer. La luminoterapia es una medida terapéutica eficaz para su tratamiento

INTRODUCTION. Most of times jaundice in newborn is a physiological fact due to hyperbilirubinemia of indirect predominance, secondary to liver immaturity and to bilirubin hyperproduction. The aim of present of present study was to determine the behavior of neonatal hyperbilirubinemia in the Gynecology and Obstetrics Teaching Hospital of Guanabacoa municipality from 2007 to 2009. METHODS. A retrospective and descriptive study was conducted in 173 newborn patients admitted in the Neonatology Department diagnosed with severe hyperbilirubinemia. RESULTS. The incidence of severe neonatal hyperbilirubinemia was of 3,67 percent with predominance in brothers with a history of jaundice (56,65 percent). The time of appearance was of 48 to 72 hrs (76,87 percent) and among the aggravating factors were the preterm birth and a low birth weight. Most of patients were treated with luminotherapy (90,17 percent). CONCLUSION. The severe neonatal hyperbilirubinemia is a health problem. Aggravating factors include the prematurity and the low birth weight. Luminotherapy is an effective therapeutic measure for its treatment

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.

UGT1A1 gene polymorphisms in North Indian neonates presenting with unconjugated hyperbilirubinemia.

Genetic factors are implicated in pathogenesis of neonatal hyperbilirubinemia. In this nested case-control study, we determined 1) frequency of thymine-adenine (TA)n promoter polymorphism and Gly71Arg mutation in uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene in neonates > or =35-wk gestation presenting with bilirubin levels > or =18 mg/dL and controls, 2) interaction among (TA)n promoter polymorphism, glucose-6-phosphate dehydrogenase (G6PD) gene mutations, and peak bilirubin. The number of TA repeats was assessed by PCR-single-strand conformation polymorphism (SSCP) analysis and Gly71Arg mutation by PCR-RFLP. Fifty samples of both mutations were verified with DNA sequencing. One hundred twenty-seven neonates were enrolled (77 hyperbilirubinemics, 50 controls). The incidence of (TA)n polymorphism was higher in babies with hyperbilirubinemia [89.6% vs. 50%, OR 8.63 (95% CI, 3.2-24.1)]. Gly71Arg mutation was not found either in hyperbilirubinemics or controls. A novel polymorphism (Ala72Pro) at codon position 72 of exon 1 was detected in all 50 samples (21 hyperbilirubinemics, 29 controls), which were sequenced. Presence of variant (TA)n promoter (adjusted OR, 10.6; 95% CI, 3.3-34.2), G6PD deficiency (adjusted OR, 20.6; 95% CI, 3.6-117.3), and history of jaundice in sibling requiring phototherapy (adjusted OR, 12.6; 95% CI, 1.1-141.6) were independent risk factors for bilirubin levels > or =18 mg/dL.

UGT1A1 haplotype mutation among Asians in Singapore.

BACKGROUND: The uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) enzyme is responsible for conjugation of the bilirubin in the liver as well as for drug metabolism. Some of the polymorphisms have been associated with an increased risk of neonatal hyperbilirubinemia which may explain the increased incidence of jaundice in an Asian population as well as exaggerated irinotecan-induced leukopenia. OBJECTIVE: The local Asian incidence of hypomorphic haplotypes, defined as gene mutations known to have a reduced function, has not been described. Clinical correlation between the mutations and the need for phototherapy for hyperbilirubinemia was carried out. METHODS: A cohort of 241 consecutive term infants delivered in the National University Hospital, Singapore, was recruited with parental consent. Cord blood was collected, and the promoter and coding regions of the UGT1A1 gene were sequenced. RESULTS: Six known haplotypes and 2 novel haplotypes were identified: 1 wild type, 5 with reduced function, while the 2 novel ones were predicted to have decreased function. The frequency of these hypomorphic haplotypes was high. Among the 241 infants screened, 35% had 1 hypomorphic haplotype and 12% had 2 hypomorphic haplotypes. The frequency was also different among ethnic groups, with 48% Chinese, 64% Indian and 31% Malay infants having at least 1 hypomorphic haplotype (chi(2) test, p < 0.05). There was a trend seen between the number of G71R mutations and the need for phototherapy (chi2 test for trend, p < 0.05). CONCLUSIONS: The local Asian incidence of hypomorphic haplotypes was high and there was a trend between the number of G71R mutations and the need for phototherapy. The G71R mutation may account for the increased incidence of neonatal jaundice seen in Asian populations.

ADA genetic polymorphism and the effect of smoking on neonatal bilirubinemia and developmental parameters.

BACKGROUND: Genetic variability of metabolic enzymes may influence the effect of cigarette smoking on intrauterine development and on early neonatal events. AIMS: To investigate the role of adenosine deaminase genetic polymorphism on the effect of smoking on neonatal bilirubinemia and developmental parameters. STUDY DESIGN: Analysis of association between adenosine deaminase phenotypes and neonatal developmental parameters. Prospective study of serum bilirubin level in relation to adenosine deaminase phenotype. METHODS: We have studied 360 consecutive newborn infants from the Caucasian population of Rome. Serum bilirubin concentration was determined at birth and every 24 h for the first five days. RESULTS: Overall maternal smoking is associated with a slight decrease in the incidence of phototherapy (13.4% in non smoking vs 11.7% in smoking mothers) and with a reduction of birth weight (3374 g in non smoking mothers vs 3133 g in smoking mothers). There is a significant interaction between smoke and adenosine deaminase. While in non smoking mothers the incidence of phototherapy in carriers of ADA 2 allele is higher than in ADA 1 phenotype, in infants from smoking mothers the pattern is reversed and the incidence of phototherapy in carriers of ADA 2 allele is lower than in infants with ADA 1 phenotype. Other neonatal bilirubin parameters follow a similar pattern of interaction between smoking and ADA. The negative effect of smoke on birth weight is much more evident in infant with ADA 1 phenotype than in those carrying the ADA 2 allele. CONCLUSIONS: The data suggest that ADA phenotype modifies the effect of smoking on developmental and bilirubin parameters.