Crigler-Najjar Syndrome Type 1: Pathophysiology, Natural History, and Therapeutic Frontier.

BACKGROUND AND AIMS: We describe the pathophysiology, treatment, and outcome of Crigler-Najjar type 1 syndrome (CN1) in 28 UGT1A1 c.222C>A homozygotes followed for 520 aggregate patient-years. APPROACH AND RESULTS: Unbound ("free") bilirubin (Bf ) was measured in patient sera to characterize the binding of unconjugated bilirubin (BT ) to albumin (A) and validate their molar concentration ratio (BT /A) as an index of neurological risk. Two custom phototherapy systems were constructed from affordable materials to provide high irradiance in the outpatient setting; light dose was titrated to keep BT /A at least 30% below intravascular BT binding capacity (i.e., BT /A = 1.0). Categorical clinical outcomes were ascertained by chart review, and a measure (Lf ) was used to quantify liver fibrosis. Unbound bilirubin had a nonlinear relationship to BT (R2  = 0.71) and BT /A (R2  = 0.76), and Bf as a percentage of BT correlated inversely to the bilirubin-albumin equilibrium association binding constant (R2  = 0.69), which varied 10-fold among individuals. In newborns with CN1, unconjugated bilirubin increased 4.3 ± 1.1 mg/dL per day. Four (14%) neonates developed kernicterus between days 14 and 45 postnatal days of life; peak BT  ≥ 30 mg/dL and BT /A ≥ 1.0 mol:mol were equally predictive of perinatal brain injury (sensitivity 100%, specificity 93.3%, positive predictive value 88.0%), and starting phototherapy after age 13 days increased this risk 3.5-fold. Consistent phototherapy with 33-103 µW/cm2 •nm for 9.2 ± 1.1 hours/day kept BT and BT /A within safe limits throughout childhood, but BT increased 0.46 mg/dL per year to reach dangerous concentrations by 18 years of age. Liver transplantation (n = 17) normalized BT and eliminated phototherapy dependence. Liver explants showed fibrosis ranging from mild to severe. CONCLUSION: Seven decades after its discovery, CN1 remains a morbid and potentially fatal disorder.

Hiperbilirrubinemias hereditarias: un diagnóstico diferencial a considerar en ictericia / Hereditary hiperbilirrubinemias: a differential diagnosis to considerer in icterus

Las hiperbilirrubinemias hereditarias (HBH) son patologías originadas por defectos en las enzimas y proteínas que participan del metabolismo de la bilirrubina. El clearence de bilirrubina incluye captación y almacenamiento en hepatocitos, conjugación, excreción hacia la bilis y recaptura de su forma conjugada por hepatocitos. Las HBH varían de acuerdo a su patogenia, presentación clínica, niveles de bilirrubinemia y tratamientos disponibles. En general son poco frecuentes, a excepción del Síndrome de Gilbert. Están las que son de predominio indirecto, como el Síndrome de Gilbert y el de Crigler-Najjar, y las de predominio directo, como el Síndrome de Dubin-Johnson y el de Rotor. En general no requieren tratamiento específico y tienen curso benigno, a excepción del Síndrome de Crigler-Najjar para el cual existen medidas terapéuticas específicas a considerar, teniendo un pronóstico reservado para algunas de sus formas de presentación. Es importante el conocimiento de estos síndromes dado el alto índice de sospecha requerido para su diagnóstico y para su diferenciación de otras patologías hepatobiliares de mayor riesgo y severidad.

Hereditary hiperbilirrubinemias (HBH) are pathologies originated from the defect of the enzymes and proteins involved in the metabolism of bilirubin. The bilirubin clearance includes uptake and storage in hepatocytes, conjugation, excretion into bile and recapture of its conjugated form by hepatocytes. HBH vary according to their pathogenesis, clinical presentation, levels of bilirubin and available treatments. Generally they are infrequent, except for Gilbert Syndrome. There are those with indirect bilirubin predominance, such as Gilbert and Crigler-Najjar syndromes, and those with direct bilirubin predominance, including Dubin-Johnson and Rotor syndromes. In general, they do not require specific treatment and have a benign course, with the exception of the Crigler-Najjar Syndrome, for which there are specific therapeutic measures to consider, as well as a reserved prognosis for some of their forms of presentation. The knowledge of these syndromes is important 2 given the high index of suspicion required for its diagnosis and for its differentiation from other hepatobiliary pathologies of greater risk and severity.

Compound heterozygosity of a novel exon 3 frameshift (p.R357P fs*24) mutation and Y486D mutation in exon 5 of the UGT1A1 gene in a Thai infant with Crigler-Najjar syndrome type 2.

Mutations in the UGT1A1 gene cause Crigler-Najjar syndrome (CN), which causes non-hemolytic unconjugated hyperbilirubinemia, and is categorized as CN1 and CN2 according to the severity of bilirubin levels. The UGT1A1 gene is responsible for encoding the liver enzyme uridine diphosphate-glucuronosyltransferase, UGT1A1. This protein adds glucuronic acid to unconjugated bilirubin in bilirubin metabolism to form conjugated bilirubin. CN2 occurs when UGT1A1 activity is low, while CN1 is the absence of UGT1A1 activity; therefore, the CN2 phenotype is not as severe as that of CN1. Here, we report a novel allele of compound heterozygous mutations in UGT1A1 in a Thai male infant with clinical symptoms of CN2. The patient's compound heterozygosity was composed of a novel mutation, c.1069-1070insC, and the c.1456T>G mutation. The novel c.1069-1070insC mutation generated a premature stop codon in exon 4 (p.R357Pfs*24). The healthy parents were heterozygous for the c.1069-1070insC mutation (father) and c.1456T>G missense mutation (mother). Our results suggest that compound heterozygosity of the novel c.1069-1070insC and c.1456T>G (c211 G >A) missense mutation in the UGT1A1 gene played a primary role in the development of CN2 unconjugated hyperbilirubinemia.

A novel stop codon mutation in exon 1 (558C>A) of the UGT1A1 gene in a Thai neonate with Crigler-Najjar syndrome type I.

Human uridine 5'-diphosphate-glucuronosyltransferases play a critical role in detoxification by conjugating bilirubin with glucoronic acid. Impaired or reduced enzymatic activity causes a spectrum of clinical disorders such as Crigler-Najjar syndrome type I (CN1), Crigler-Najjar syndrome type II, and Gilbert's syndrome. CN1 is a severe form of unconjugated hyperbilirubinemia caused by homozygous or compound heterozygous mutations in the gene for uridine 5'-diphosphate glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1), resulting in complete loss of enzyme function. Here, we report a novel homozygous mutation of UGT1A1 in a female Thai infant who was diagnosed with CN1, and her parents were found to be heterozygous carriers. The patient was homozygous for the c.558C>A mutation, which resulted in a premature stop codon in exon 1. Her asymptomatic parents were carriers of the nonsense c.558C>A mutation. Our result suggests an important role for homozygous c.558C>A mutations in the UGT1A1 gene in the development of severe unconjugated hyperbilirubinemia.

[Crigler-Najjar syndrome. Report of one case with a long term follow up]. / Evolución prolongada en síndrome de Crigler-Najjar tipo I.

Crigler-Najjar Syndrome is an uncommon genetic disorder characterized by the elevation of unconjugated plasmatic bilirubin secondary to deficiency of the enzyme uridine diphosphate glucuronyltransferase (UDP-GT). We report a 19-years-old woman with the syndrome diagnosed during the neonatal period, when she developed a severe jaundice in the first 10 days of life, reaching unconjugated bilirubin levels of 29 mg/dl, with normal liver function tests. After transient response to phototherapy, the patient was referred to a tertiary medical center in which an extensive work up ruled out other etiologies and the diagnosis of type I Crigler-Najjar syndrome was established. Currently, the patient has a mild mental retardation. She is receiving homemade phototherapy 18 h per day with acceptable control of bilirubin levels. Many mutations have been associated with UDP-GT dysfunction resulting in a broad spectrum of the disease. When bilirubin rises above physiological limits, it permeates the hematoencephalic barrier, inducing bilirubin impregnation of basal ganglia with secondary neuronal damage and necrosis. The worst outcome, kernicterus, is characterized by mental retardation, central deafness, ophthalmoplegia, ataxia, athetosis, spasticity, seizures and death. First line therapy includes phototherapy, but definitive therapy is liver transplantation before the occurrence of neurological damage.

Evolución prolongada en síndrome de Crigler-Najjar tipo I / Crigler-Najjar syndrome. Report of one case with a long term follow up

Crigler-Najjar Syndrome is an uncommon genetic disorder characterized by the elevation of unconjugated plasmatic bilirubin secondary to deficiency of the enzyme uridine diphosphate glucuronyltransferase (UDP-GT). We report a 19-years-old woman with the syndrome diagnosed during the neonatal period, when she developed a severe jaundice in the first 10 days of life, reaching unconjugated bilirubin levels of 29 mg/dl, with normal liver function tests. After transient response to phototherapy, the patient was referred to a tertiary medical center in which an extensive work up ruled out other etiologies and the diagnosis of type I Crigler-Najjar syndrome was established. Currently, the patient has a mild mental retardation. She is receiving homemade phototherapy 18 h per day with acceptable control of bilirubin levels. Many mutations have been associated with UDP-GT dysfunction resulting in a broad spectrum of the disease. When bilirubin rises above physiological limits, it permeates the hematoencephalic barrier, inducing bilirubin impregnation of basal ganglia with secondary neuronal damage and necrosis. The worst outcome, kernicterus, is characterized by mental retardation, central deafness, ophthalmoplegia, ataxia, athetosis, spasticity, seizures and death. First line therapy includes phototherapy, but definitive therapy is liver transplantation before the occurrence of neurological damage.

Role of a homozygous A(TA)7TAA promoter polymorphism and an exon 1 heterozygous frameshift mutation UGT1A1 in Crigler-Najjar syndrome type II in a Thai neonate.

Crigler-Najjar syndrome is a rare autosomal recessive disease caused by mutations in the UGT1A1 gene. These mutations result in the deficiency of UGT1A1, a hepatic enzyme essential for bilirubin conjugation. This report describes the case of a 4-month-old boy with the cardinal symptoms of Crigler-Najjar syndrome type II. Molecular genetic analysis showed a homozygous UGT1A1 promoter mutation [A(TA)7TAA] and a heterozygous insertion of 1 adenosine nucleotide between positions 353 and 354 in exon 1 of UGT1A1 that caused a frameshift with a premature stop codon.

UGT1A1 genetic analysis as a diagnostic aid for individuals with unconjugated hyperbilirubinemia.

OBJECTIVE: To assess the clinical utility of UGT1A1 genetic testing and describe the spectrum and prevalence of UGT1A1 variations identified in pediatric unconjugated hyperbilirubinemia (UCH), and to characterize specific genotype-phenotype relationships in suspected Gilbert and Crigler-Najjar syndromes. STUDY DESIGN: A retrospective study was conducted to review clinical information and UGT1A1 genotyping data from 181 pediatric patients referred for UCH. In silico analyses were performed to aid in the assessment of novel UGT1A1 variants. RESULTS: Overall, 146/181 pediatric patients had at least one heterozygous UGT1A1 functional variant. Identified UGT1A1 variants included 17 novel variants, 7 rare star alleles, and 1 rare variant. There were 129 individuals who possessed the TA7 (*28) promoter repeat and 15 individuals who possessed the *6 (c.211G > A) variation. Out of the 104 individuals with accompanying bilirubin levels, 41 individuals did not have identifiable UGT1A1 variants that explained their UCH, although glucose-6-phosphate dehydrogenase deficiency and other causes of UCH could not be ruled out. CONCLUSION: Much of the observed UCH could be attributed to variation at the UGT1A1 locus, and UGT1A1 testing helped to substantiate a genetic diagnosis, thereby aiding in individual and family disease management. Although UGT1A1 variation plays a large role in UCH, genetic assessment of UGT1A1 alone may not be comprehensive. Assessment of additional genes may also be useful to evaluate genetic causes for UCH.

Orthodontic treatment of a child with Crigler-Najjar syndrome type I using tacrolimus following liver transplantation.

The present study reports the orthodontic treatment of a child with Crigler-Najjar syndrome type I following a liver transplant and administration of tacrolimus (1 mg/day). Tacrolimus (FK506) is fundamental to immunosuppression following transplantation. The child exhibited Class II division 1 malocclusion. The treatment option was to use a Herbst appliance for seven months and a fixed appliance (straight wire) for 12 months.

Hiperbilirrubinemia indirecta de origen genético: informe de un caso de síndrome de Crigler-Najjar de tipo II / Indirect hyperbilirubinemia of genetic origin: case report of Crigler-Najjar syndrome type II

El síndrome de Crigler Najjar II aparece por un déficit en la conjugación de la bilirrubina debido a la deficiencia parcial de la enzima uridindifosfato-glucuronil transferasa. Por lo general, tiene un curso benigno, a diferencia del Crigler Najjar de tipo I, donde el déficit enzimático es total y los afectados mueren a edades tempranas. Se presenta el caso de una adolescente de16 años con hiperbilirrubinemia indirecta, síndrome convulsivante y parálisis cerebral. Una correcta historia clínica con estudio genealógico y pruebas funcionales apropiadas, permitieron determinar el diagnóstico definitivo. Esta enfermedad genética se transmite de forma autosómica recesiva, tiene una prevalencia muy baja a nivel mundial y constituye, en general, un reto diagnóstico para los médico.

Crigler Najjar syndrome type II is related to a defect of bilirubin conjugation due to partial deficiency of the enzyme uridine diphosphate-glucuronyl transferase. Usually has a benign course, unlike Crigler Najjar type I, where the enzyme deficiencyis total and the affected patients usually die at early ages. We present the case of a teenager with indirect hyperbilirubinemia, seizures and cerebral palsy. A good clinical historywith pedigree and appropriate functional tests allowed us to determine the definitive diagnosis. This is an autosomal recessive disorder, has a very low prevalence worldwide, and is adiagnostic challenge for physicians in general.

Hiperbilirrubinemia indirecta de origen genético: informe de un caso de síndrome de Crigler-Najjar de tipo II / Indirect hyperbilirubinemia of genetic origin: case report of Crigler-Najjar syndrome type II

El síndrome de Crigler Najjar II aparece por un déficit en la conjugación de la bilirrubina debido a la deficiencia parcial de la enzima uridindifosfato-glucuronil transferasa. Por lo general, tiene un curso benigno, a diferencia del Crigler Najjar de tipo I, donde el déficit enzimático es total y los afectados mueren a edades tempranas. Se presenta el caso de una adolescente de16 años con hiperbilirrubinemia indirecta, síndrome convulsivante y parálisis cerebral. Una correcta historia clínica con estudio genealógico y pruebas funcionales apropiadas, permitieron determinar el diagnóstico definitivo. Esta enfermedad genética se transmite de forma autosómica recesiva, tiene una prevalencia muy baja a nivel mundial y constituye, en general, un reto diagnóstico para los médico.(AU)

Crigler Najjar syndrome type II is related to a defect of bilirubin conjugation due to partial deficiency of the enzyme uridine diphosphate-glucuronyl transferase. Usually has a benign course, unlike Crigler Najjar type I, where the enzyme deficiencyis total and the affected patients usually die at early ages. We present the case of a teenager with indirect hyperbilirubinemia, seizures and cerebral palsy. A good clinical historywith pedigree and appropriate functional tests allowed us to determine the definitive diagnosis. This is an autosomal recessive disorder, has a very low prevalence worldwide, and is adiagnostic challenge for physicians in general.(AU)

[Indirect hyperbilirubinemia of genetic origin: Case report of Crigler-Najjar syndrome type II]. / Hiperbilirrubinemia indirecta de origen genético: Informe de un caso de síndrome de Crigler-Najjar de tipo II.

Crigler Najjar syndrome type II is related to a defect of bilirubin conjugation due to partial deficiency of the enzyme uridine diphosphate-glucuronyl transferase. Usually has a benign course, unlike Crigler Najjar type I, where the enzyme deficiency is total and the affected patients usually die at early ages. We present the case of a teenager with indirect hyperbilirubinemia, seizures and cerebral palsy. A good clinical history with pedigree and appropriate functional tests allowed us to determine the definitive diagnosis. This is an autosomal recessive disorder, has a very low prevalence worldwide, and is a diagnostic challenge for physicians in general.

Sindrome de crigler-najjar: variabilidad clínica / Crigler-najjar syndrome: clinical variability

El síndrome de Crigler Najjar (SCN), de Herencia autosómica recesiva, es un trastorno causado por una deficiencia de la enzima bilirrubin UDP glucuronil transferasa. Se describen dos tipos de acuerdo a la ausencia o reducción de la actividad enzimática. Los pacientes presentan ictericia con aumento de bilirrubina inderecta desde el nacimiento y riesgo de Kernnícterus. El tratamiento consiste en exsanguino transfuciones (EXT) durante el período neonatal y lumino terapia (LMT) diaria prolongada. El transplante hepático es la única opción terapéutica curativa para el tipo 1. El tipo 2 responde al fenobarbital. El objetivo de este trabajo fue analizar retrospectivamente dos pacientes con SCN. En ambas se descartaron otras causas de hiperbilirrubinemia inderecta. Caso Clínico 1: Sexo femenino, eutrófica, comenzó con ictericia a los 3 días de vida, 72 horas más tarde la bilirrubina total (BT) era de 24mg/dl a predominio indirecto (BI), recibió LMT hasta los 25 días de vida, luego fenobarbital y LMT domiciliaria, 8 horas/día, con buena respuesta. A los 8 meses, con una BI 5.5 mg/dl se suspendió la LMT. Los valores de BI posteriores oscilaron entre 6 8 mg/dl, bajo tratamiento con FB. Debido a su evolucion clínica, se planteó como diagnóstico SCN tipo 2. Caso Clínico 2: Sexo femenino, eutrófica, presentó ictericia desde los 12 días de vida, con niveles de BI de 39mg/dl, se realizaron EXT y LMT. El examen neurológico era normal. Se indicó LMT domiciliaria 12 16 Hs/d y FB. La paciente persistió con valores de BI>20mg/dl. Se asumió como probable SCN tipo 1. Se inició evaluación pre trasplante hepático.Palabras clave: síndrome de Crigler Najjar, dianóstico, tratamiento, evolución

Sindrome de crigler-najjar: variabilidad clínica / Crigler-najjar syndrome: clinical variability

El síndrome de Crigler Najjar (SCN), de Herencia autosómica recesiva, es un trastorno causado por una deficiencia de la enzima bilirrubin UDP glucuronil transferasa. Se describen dos tipos de acuerdo a la ausencia o reducción de la actividad enzimática. Los pacientes presentan ictericia con aumento de bilirrubina inderecta desde el nacimiento y riesgo de Kernnícterus. El tratamiento consiste en exsanguino transfuciones (EXT) durante el período neonatal y lumino terapia (LMT) diaria prolongada. El transplante hepático es la única opción terapéutica curativa para el tipo 1. El tipo 2 responde al fenobarbital. El objetivo de este trabajo fue analizar retrospectivamente dos pacientes con SCN. En ambas se descartaron otras causas de hiperbilirrubinemia inderecta. Caso Clínico 1: Sexo femenino, eutrófica, comenzó con ictericia a los 3 días de vida, 72 horas más tarde la bilirrubina total (BT) era de 24mg/dl a predominio indirecto (BI), recibió LMT hasta los 25 días de vida, luego fenobarbital y LMT domiciliaria, 8 horas/día, con buena respuesta. A los 8 meses, con una BI 5.5 mg/dl se suspendió la LMT. Los valores de BI posteriores oscilaron entre 6 8 mg/dl, bajo tratamiento con FB. Debido a su evolucion clínica, se planteó como diagnóstico SCN tipo 2. Caso Clínico 2: Sexo femenino, eutrófica, presentó ictericia desde los 12 días de vida, con niveles de BI de 39mg/dl, se realizaron EXT y LMT. El examen neurológico era normal. Se indicó LMT domiciliaria 12 16 Hs/d y FB. La paciente persistió con valores de BI>20mg/dl. Se asumió como probable SCN tipo 1. Se inició evaluación pre trasplante hepático.Palabras clave: síndrome de Crigler Najjar, dianóstico, tratamiento, evolución

Transplante hepático en una paciente con daño neurológico ¿un recurso terapéutico excepcional?: algunas reflexiones bioéticas / Liver transplantation in a patient with neurological damage: a one-off treatment?: some bioethical considerations

Se presenta el dilema ético-clínico planteado por el caso de una paciente de 8 años 6 meses de edad, portadora de enfermedad hepática con daño neurológico irreversible y severo en la cual los padres solicitan la posibilidad de realizar un transplante hepático. Se trata de la única hija de padres sanos, preocupados y responsables del manejo de su hija, con un riesgo de recurrencia de esta enfermedad de 25 porciento para otro hijo. Se discuten las posibilidades de hacer todo lo terapéuticamente posible o si se debe tomar la decisión de limitar los tratamientos. Con el objetivo de mostrar un proceso de deliberación bioética y de permitir al lector confrontar sus apreciaciones personales, se presenta el caso clínico, seguido de dos comentarios independientes

Ictericia neonatal I. fisiopatología, etiología, diagnóstico y encefalopatía bilirrubínica / Neonatal jaindice I. phisiology, etiology, diagnosis, and bilirubin encephalopathy

La ictericia neonatal es uno de los principales problemas a que se enfrentan los pediatras y neonatólogos en la consulta externa y en las áreas de urgencias y hospitalización. Decidir cuándo esta ictericia es fisiológica y cuándo requiere un abordaje completo a fin de determinar el origen y establecer el tratamiento adecuado, es uno de los retos más grandes en los últimos años debido a la falta de consenso entre los diferentes grupos de especialistas. En esta revisión se presentan aspectos de fisiopatología para entender mejor los mecanismos de producción de hiperbilirrubinemia indirecta en el neonato, se analizan las principales causas de ésta y se hace hincapié en los problemas hemolíticos y los conceptos actuales con relación a la ictericia por leche materna. Asimismo se presentan algunas entidades no tan comunes pero que deben considerarse en el diagnóstico diferencial de estos pacientes. Se presentan de manera modificada las recomendaciones de 1994 de la Academia Americana de Pediatría para el abordaje diagnóstico de estos niños al tomar en cuenta las características particulares de nuestra población y también se analizan los mecanismos implicados en la encefalopatía bilirrubínica, el cuadro clínico y algunas controversias relacionadas con el neurodesarrollo de estos niños.