Dynamic whole-transcriptome landscape of acute bilirubin encephalopathy in newborns.

Hyperbilirubinemia in newborns may progress to acute bilirubin encephalopathy (ABE), posing short- and long-term health risks. Despite extensive research identifying numerous mRNAs, lncRNAs, circRNAs, and miRNAs associated with brain injury, their roles in neonatal bilirubin-induced brain injury remain elusive. This study employed whole-transcriptome sequencing to ascertain the differentially expressed (DE) RNA profiles in a newborn ABE rat model, followed by bioinformatic analysis. A time-series competing endogenous RNA (ceRNA) regulatory network was established, and the expression trends of 9 arbitrarily chosen RNAs were verified through quantitative real-time polymerase chain reaction(qRT-PCR). In comparison with the control group, we identified 595, 888, and 1448 DE mRNAs; 22, 37, and 37 DE miRNAs; 1945, 1869, and 1997 DE lncRNAs; and 31, 28, and 36 DE circRNAs at 6 h, 12 h, and 24 h, respectively. Predominantly, these DERNAs contribute to biological functions and pathways associated with inflammation, immunity, metabolism, cell death, and neurodevelopmental regulation. Moreover, we constructed ceRNA networks of DE lncRNA/circRNA-DE miRNA-DE mRNA based on time series. The qRT-PCR expression trends for the selected 9 RNAs were generally similar to the RNA-seq outcomes. This investigation uniquely delineated the temporal expression patterns of mRNA and non-coding RNA in ABE, establishing ceRNA networks and identifying potential molecular mechanisms underlying bilirubin-induced hippocampal damage. Nonetheless, further studies are warranted to corroborate these findings in humans.

Thirty-five males with severe (Class 1) G6PD deficiency (c.637G>T) in a North American family of European ancestry.

In North America, jaundiced neonates are not usually tested for G6PD deficiency if the family is of European ancestry. However, we describe such a family where ≥35 males have had severe (Class I) G6PD deficiency. Many of the jaundiced neonates did not have this diagnosis considered, at least three of whom developed bilirubin neurotoxicity. Over seven generations 35 affected males were identified. Three developed signs of kernicterus spectrum disorder; three had exchange transfusions for hyperbilirubinemia; and nine received one or more blood transfusions during childhood.

High levels of pathological jaundice in the first 24 hours and neonatal hyperbilirubinaemia in an epidemiological cohort study on the Thailand-Myanmar border.

Population risks for neonatal hyperbilirubinaemia (NH) vary. Knowledge of local risks permits interventions that may reduce the proportion becoming severe. Between January 2015 and May 2016, in a resource-limited setting on the Thailand-Myanmar border, neonates from 28 weeks' gestation were enrolled into a prospective birth cohort. Each neonate had total serum bilirubin measurements: scheduled (24, 48, 72 and 144 hours of life) and clinically indicated; and weekly follow up until 1 month of age. Risk factors for developing NH were evaluated using Cox proportional hazard mixed model. Of 1710 neonates, 22% (376) developed NH (83% preterm, 19% term). All neonates born <35 weeks, four in five born 35-37 weeks, and three in twenty born ≥38 weeks had NH, giving an overall incidence of 249 per 1000 livebirths [95%CI 225, 403]. Mortality from acute bilirubin encephalopathy was 10% (2/20) amongst the 5.3% (20/376) who reached the severe NH threshold. One-quarter (26.3%) of NH occurred within 24 hours. NH onset varied with gestational age: at a median [IQR] 24 hours [24, 30] for neonates born 37 weeks or prematurely vs 59 hours [48, 84] for neonates born ≥38 weeks. Risk factors for NH in the first week of life independent of gestational age were: neonatal G6PD deficiency, birth bruising, Sgaw Karen ethnicity, primigravidae, pre-eclampsia, and prolonged rupture of membranes. The genetic impact of G6PD deficiency on NH was partially interpreted by using the florescent spot test and further genotyping work is in progress. The risk of NH in Sgaw Karen refugees may be overlooked internationally as they are most likely regarded as Burmese in countries of resettlement. Given high levels of pathological jaundice in the first 24 hours and overall high NH burden, guidelines changes were implemented including preventive PT for all neonates <35 weeks and for those 35-37 weeks with risk factors.

Review of bilirubin neurotoxicity I: molecular biology and neuropathology of disease.

Despite the availability of successful prevention strategies to prevent excessive hyperbilirubinemia, the neurological sequelae of bilirubin neurotoxicity (BNTx) still occur throughout the world. Kernicterus, encephalopathy due to BNTx, is now understood to be a spectrum of severity and phenotypes known as kernicterus spectrum disorder (KSD). A better understanding of the selective neuropathology and molecular biology of BNTx and using consistent clinical definitions of KSDs as outcome measure can lead to more accurately predicting the risk and causes of BNTx and KSDs. In Part I of our two-part review, we will summarize current and recent advances in the understanding of the selective neuropathology and molecular biology of the disease. Herein we emphasize the role of unbound, free unconjugated bilirubin as well as genetic contributions to the susceptibility BNTx and the development of KSDs. In Part II, we focus on current and possible novel methods to prevent BNTx and ABE and treat ABE and KSDs.

The Neonatal Acute Bilirubin Encephalopathy Registry (NABER): Background, Aims, and Protocol.

BACKGROUND: Acute bilirubin encephalopathy (ABE) is a potentially devastating condition that can lead to death or life-long neurodevelopmental handicaps. ABE is particularly tragic because it is, in theory, completely preventable. Progress toward its prevention has been hampered by the perception that the extreme hyperbilirubinemia giving rise to ABE typically has no clear causation, with the majority of previous cases being labeled as "idiopathic" neonatal jaundice. OBJECTIVES: This research briefing is intended to inform readers of a new prospective study aimed at clarifying the causes of ABE. This is accomplished by identifying qualifying patients with ABE anywhere in the USA and then documenting their clinical characteristics and the results of testing 28 specific genetic associations in a web-based, institutional review board-approved, REDCap (research electronic data capture) deidentified registry. METHODS: In this research briefing, we present an overview of ABE and discuss the problem that most patients in the past have been labeled as having "idiopathic" hyperbilirubinemia. We also present data supporting a new theory that most (perhaps all) ABE patients have mutations or polymorphisms in genes involved in bilirubin production or metabolism. We introduce a new registry seeking to enroll 100 neonates with ABE as a voluntary, deidentified database, with next generation sequencing of 28 genes involved in bilirubin production/metabolism provided to enrollees at no cost. RESULTS AND CONCLUSIONS: The Neonatal Acute Bilirubin Encephalopathy Registry (NABER) study will correlate deidentified clinical and genetic data in order to clarify the underlying causes of hyperbilirubinemia in current ABE patients. We maintain that the improved understanding this study produces will constitute a needed step toward devising new clinical pathways and strategies for preventing ABE in neonates.

Acute neonatal bilirubin encephalopathy in the State of Utah 2009-2018.

Herein we report a case series of seven newborn infants, all apparently well at birth, who in the period since 2009 were cared for in the State of Utah with acute bilirubin encephalopathy (ABE). This report summarizes our attempts to define common features of these seven through a state-wide voluntary registry, as a step toward devising new means of preventing such cases in the future. In previous reports of ABE, many of the affected neonates had no clearly defined explanation for their progressive hyperbilirubinemia. Our efforts to identify clear explanations in all seven cases included next generation DNA sequencing, testing a panel of 28 genes involved in bilirubin production and metabolism. We found that hemolytic disease was a unifying feature of these seven; two had DAT (+) Anti-D or anti-c hemolysis, while five had confirmed mutations in genes involved in bilirubin production and or metabolism that were previously unrecognized in these families.

Developmental onset of bilirubin-induced neurotoxicity involves Toll-like receptor 2-dependent signaling in humanized UDP-glucuronosyltransferase1 mice.

Biological and signaling events that connect developmentally induced hyperbilirubinemia to bilirubin-induced neurological dysfunction (BIND) and CNS toxicity in humans are poorly understood. In mammals, UDP-glucuronosyltransferase 1A1 (UGT1A1) is the sole enzyme responsible for bilirubin glucuronidation, a rate-limiting step necessary for bilirubin metabolism and clearance. Humanized mice that express the entire UGT1 locus (hUGT1) and the UGT1A1 gene, develop neonatal hyperbilirubinemia, with 8-10% of hUGT1 mice succumbing to CNS damage, a phenotype that is presented by uncontrollable seizures. We demonstrate that neuroinflammation and reactive gliosis are prominent features of bilirubin brain toxicity, and a disturbed redox status resulting from activation of NADPH oxidase is an important contributing mechanism found in BIND. Using knock-out mice and primary brain cells, we connect a key pattern recognition receptor, Toll-like receptor 2 (TLR2), to hyperbilirubinemia-induced signaling. We illustrate a requirement for TLR2 signaling in regulating gliosis, proinflammatory mediators, and oxidative stress when neonatal mice encounter severe hyperbilirubinemia. TLR2-mediated gliosis strongly correlates with pronounced neuroinflammation in the CNS with up-regulation of TNFα, IL-1ß, and IL-6, creating a pro-inflammatory CNS environment. Gene expression and immunohistochemistry staining show that hUGT1/Tlr2(-/-) mice fail to activate glial cells, proinflammatory cytokines, and stress response genes. In addition, bilirubin-induced apoptosis was significantly enhanced by blocking TLR2 signaling indicating its anti-apoptotic property. Consequently, a higher neonatal death rate (57.1%) in hUGT1/Tlr2(-/-) mice was observed when compared with hUGT1 mice (8.7%). These results suggest that TLR2 signaling and microglia neuroinflammation are linked to a repair and/or protection mode against BIND.

Acute kernicterus in a neonate with O/B blood group incompatibility and a mutation in SLC4A1.

We cared for a term female newborn, who at 108 hours of age, with a total serum bilirubin of 15.4 mg/dL, was discharged from the hospital on home phototherapy. At a return appointment 44 hours later, her total serum bilirubin was 41.7 mg/dL and signs of acute kernicterus were present. Maternal/fetal blood group O/B incompatibility was identified, with a negative direct antiglobulin test, which was positive on retesting. She had abundant spherocytes on blood smear, and these persisted at follow-up, but neither parent had spherocytes identified. A heterozygous SLC4A1(E508K) mutation (gene encoding erythrocyte membrane protein band 3) was found, and in silico predicted to result in damaged erythrocyte cytoskeletal protein function. No mutations were identified in other red cell cytoskeleton genes (ANK1, SPTA1, SPTB, EPB41, EPB42) and the UGT1A1 promoter region was normal. Neurologic follow-up at 2 and 4 months showed developmental delays consistent with mild kernicterus.

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.

Neonatal cholestasis and glucose-6-P-dehydrogenase deficiency.

We report a Caucasian neonate with chronic non-spherocytic hemolytic anemia due to a class I G6PD deficiency. A novel mutation missense mutation in exon eight of the G6PD gene was detected (c.827C>T p.Pro276Leu). Bilirubin peaked on day 5 at 24 mg/dl with a conjugated bilirubin of 17 mg/dl. Jaundice resolved within 4 weeks. A detailed work-up failed to reveal other specific factors contributing to cholestasis. Severe hemolytic disease of the newborn may cause cholestasis even in the absence of associated primary hepato-biliary disease.

Heterologous assisted reproduction and kernicterus: the unlucky coincidence reveals an ethical dilemma.

Secrecy and anonymity related to heterologous assisted reproduction may hide basic newborn data to neonatologists. Secrecy and anonymity are discussed in view of their possible consequences on relational dynamics and on developmental psychology. Nevertheless, they can also involve the offspring's genetic status regarding inheritable diseases. International guidelines have been recently published on this topic. Because no guidelines are 'ideal' unfortunate and possibly dramatic consequences can occur. We aimed to embark on a debate about this matter starting with a real clinical experience. In our case a rarely fatal but widespread disease, together with the lack of knowledge about parental status led, in a fast succession of clinical events, to the unavoidable insurgence of kernicterus.

Genetic factors in neonatal hyperbilirubinemia and kernicterus.

Although the relationship between hyperbilirubinemia and genetic factors has long been questioned, the role of genetic factors in the development of severe hyperbilirubinemia and kernicterus has been investigated in detail in the last decade with the rapid progression in molecular medicine. Although the first historical data gathered about genetical tendency to neonatal hyperbilirubinemia dates back to description of the Crigler-Najjar syndrome in 1952, a substantial interest is currently focused on coding and promoter region mutations of uridine diphosphoglucuronate glucuronosyltransferase 1A1 gene. In this article, the role of uridine diphosphoglucuronate glucuronosyltransferase gene mutations in neonatal significant hyperbilirubinemia and kernicterus is reviewed together with the clinical presentations of the most common syndromes of bilirubin conjugation, such as Gilbert and Crigler-Najjar syndromes. Genetic counseling and investigation may be useful and necessary in newborns presenting with severe, unexplained familial hyperbilirubinemia. In these various syndromes where enzymatic and genetic deficiencies are present, studies about treatment with gene replacement, though currently experimental, are ongoing, especially in type 1 Crigler-Najjar.

Reduction of bilirubin by targeting human heme oxygenase-1 through siRNA.

Neonatal hyperbilirubinemia is a common clinical condition caused mainly by the increased production and decreased excretion of bilirubin. Current treatment is aimed at reducing the serum levels of bilirubin. Heme oxygenase-1 (HO-1) is a rate-limiting enzyme that generates bilirubin. In this study we intended to suppress HO-1 using the RNA interference technique. Small interfering RNA (siRNA)-A, -B, and -C were designed based on human HO-1 (hHO-1) mRNA sequences. siRNA was transfected into a human hepatic cell line (HL-7702). hHO-1 transcription and protein levels were then determined. In addition, the inhibitory effect of siRNA on hHO-1 was assessed in cells treated with hemin or transfected with an hHO-1 plasmid. siRNA-C showed the most potent suppressive effect on hHO-1. This inhibition is dose and time dependent. Compared with control, both hemin and hHO-1 plasmids up-regulated hHO-1 expression in HL-7702 cells. However, the up-regulation was significantly attenuated by siRNA-C. Furthermore, the decrease in hHO-1 activity was coincident with the suppression of its transcription. Finally, siRNA-C was shown to reduce hHO-1 enzymatic activity and bilirubin levels. Thus, this study provides a novel therapeutic rationale by blocking bilirubin formation via siRNA for preventing and treating neonatal hyperbilirubinemia and bilirubin encephalopathy at an early clinical stage.

Identification of the deletions in the UGT1A1 gene of the patients with Crigler-Najjar syndrome type I from Slovakia.

Crigler-Najjar syndrome type I (CN I) is a rare autosomal recessive disorder due to hepatic dysfunction of uridine diphospho-glucuronosyltransferase (UGT) activity toward bilirubin. Complete inactivation of this enzyme causing CN I lead to accumulation of unconjugated bilirubin in serum and bile. Here we report the results of the molecular characterization of the uridine diphospho-glucuronosyltransferase 1A1 (UGT1A1) gene in a consanguineous family of Slovak Roms and an unrelated non-Romany family with CN I. Sequence analysis of UGT1A1 gene in all four Romany patients showed mutation in exon 4, a deletion of an A at codon 407 (1220delA), not yet described in homozygous status. All analysed patients were homozygous for 1220delA mutation and their 3 healthy sibs were heterozygous. The non-Romany patient was a compound heterozygote for two different deletions, 1220delA and 717-718delAG at codon 239. In the family of his cousin a son was born affected with CN I, who was homozygote for 717-718delAG mutation. His other niece affected with CN II was heterozygote for mutation 717-718delAG but homozygote for TA insertion and enhancer substitution T-3279G. Haplotype analysis suggests that the 1220delA mutation is identical by descent in both families, though they originate from two ethnically different populations (Slovaks vs. Roms).

Kernicterus associated with hereditary spherocytosis and UGT1A1 promoter polymorphism.

INTRODUCTION: An apparent re-emergence of kernicterus has been recently reported, with some cases occurring in otherwise healthy breastfed newborn. METHODS: We describe a case of kernicterus in a term Caucasian newborn. RESULTS: An exceptional polymorphism of UGT1A1 gene promoter co-existed with asymptomatic inherited spherocytosis, due to erythroid anion exchange (band-3) deficiency. Both concurred to the development of severe neonatal hyperbilirubinaemia. CONCLUSION: As some cases of kernikterus remain unresolved, haemolytic diseases and bilirubin metabolism disorders should be carefully investigated in unexplained severe neonatal hyperbilirubinaemia.

Cerebellar symptoms heralding bilirubin encephalopathy in Crigler-Najjar syndrome.

Children with Crigler-Najjar syndrome type I are at increased risk for neurologic deficits. Cerebellar symptoms are not prominent and appear in adolescent or adult patients with this syndrome. We report a 2-year-old female with Crigler-Najjar syndrome type I who presented severe cerebellar symptoms revealing bilirubin encephalopathy. The patient improved slowly with the duration of phototherapy. Cerebellar symptoms can be the initial manifestation of kernicterus in children with Crigler-Najjar syndrome type I.