[Advances in research on the clinical phenotype and genetic etiology of jaundice associated with Hereditary bilirubin metabolic disorders]

Hereditary bilirubin metabolic disorder is an important cause for jaundice. For its diverse types and similar clinical manifestations, it has been difficult to make a clear etiological diagnosis. The application of next generation sequencing in recent years has delineated the more and more genetic etiologies for jaundice. This article has reviewed the clinical manifestations and genetic etiology of bilirubin metabolic disorder jaundice, with an aim to enhance the understanding of such diseases and facilitate their clinical diagnosis and treatment, which will provide a reference for genetic counseling and/or prenatal diagnosis for the affected individuals and families.

Dizygotic twins with prolonged jaundice and microcytic, hypochromic, hemolytic anemia with pyropoikilocytosis

Dizygotic twin males, born at 34 weeks gestation, had prolonged jaundice, microcytic, hypochromic anemia, FABarts hemoglobin, elevated end-tidal CO, and blood films consistent with hereditary pyropoikilocytosis. DNA sequencing revealed both had a heterozygous alpha spectrin (SPTA1) mutation (c.460_462dup) inherited from their asymptomatic mother, plus a 3-base pair duplication in alpha globin (HBA2) (c.364_366dupGTG) inherited from their asymptomatic father.

Biliary atresia combined with progressive familial intrahepatic cholestasis type 3: A case report and review of the literature

RATIONALE

Neonatal cholestasis is one of the most serious diseases in infancy. Progressive familial intrahepatic cholestasis (PFIC) is a disease that leads to intrahepatic cholestasis. It is one of the common causes of neonatal cholestasis in addition to biliary atresia (BA). The differential diagnosis of neonatal cholestasis is clinically challenging for pediatricians.

PATIENT CONCERNS

A 4-month-old female presented with severe jaundice, pruritus, and pale stool for 20 days. Abnormally strong echoes near the portal area, an abnormally small gallbladder with an irregularly stiff wall, and splenomegaly were identified on abdominal ultrasound. Blood tests showed elevated alanine aminotransferase, total bilirubin, conjugated bilirubin, gamma-glutamyltranspeptidase, and total bile acid levels.

DIAGNOSIS

Intraoperative cholangiography showed BA. ABCB4 gene mutation IVS13+6G>A/G was confirmed by genetic testing. The patient was diagnosed with BA combined with PFIC3.

INTERVENTIONS

Kasai portoenterostomy and ursodeoxycholic acid were used for treatment.

OUTCOMES

Her clinical symptoms and blood tests improved gradually. No recurrence was noted during 1 year of follow-up.

LESSONS

Additional examinations, such as genetic testing, should be considered in patients with BA who had refractory jaundice after Kasai portoenterostomy in order to exclude intrahepatic cholestasis.

IL-28B genetic variation, gender, age, jaundice, hepatitis C virus genotype, and hepatitis B virus and HIV co-infection in spontaneous clearance of hepatitis C virus

BACKGROUND/AIMS

Spontaneous viral clearance observed in some patients is one of the variants of the hepatitis C virus (HCV) infection natural history. We aimed to look at the complexity of factors affecting the spontaneous clearance of HCV (SC HCV).

MATERIALS AND METHODS

A total of 357 anti-HCV positive patients (309 with chronic hepatitis C and 48 patients with SC HCV) were included into the study. We studied the effects of the interleukin-28B (IL-28B) gene polymorphism, gender, age, the routes of virus transmission, past hepatitis C with jaundice, HCV genotype, and hepatitis B virus (HBV) and HIV co-infection on the outcome of HCV infection.

RESULTS

Based on the study results, the SC HCV was found in 48 individuals (13.4%). The most significant positive factors affecting the SC HCV included IL-28B single nucleotide polymorphism (SNP) rs12979860 (CC) and SNP rs8099917 (TT) (OR 4.03, p<0.001) and (OR 3.14, p<0.002), female gender (OR 2.72, p<0.001), young age (OR 2.30, p<0.008), and past history of jaundice (OR 5.12, p<0.001). The markers of a past HBV infection were found significantly more often in SC.

CONCLUSION

Positive predictors of the SC HCV include favorable IL-28B genotype, female gender, young age, a history of jaundice, markers of a past HBV infection, the absence of HIV infection, but not the viral genotype.

Severe Hemolytic Jaundice in a Neonate with a Novel COL4A1 Mutation

We report our experience with a preterm infant with severe hemolytic jaundice who required exchange transfusion just after birth. The patient was negative for alloimmune hemolysis as a result of maternal-fetal blood type incompatibility, and tests for inherited defects in erythrocyte metabolism, membrane function, and hemoglobin synthesis were normal. We also performed a bone marrow examination, but could not identify the cause of hemolysis. The patient had several other complications, including porencephaly, epilepsy, elevated serum levels of creatine kinase, and persistent microscopic hematuria. Later, we detected a genetic mutation in COL4A1, which was recently found to be associated with hemolytic anemia. We therefore believe that all of the patient's clinical features, including hemolytic anemia, were due to the mutation in COL4A1. Genetic testing for COL4A1 mutations is recommended in neonates who exhibit hemolytic disease of unknown etiology, especially when other complications compatible with COL4A1-related disorders are present.

Haemoglobin SD disease--rare case of jaundice

A 15 years old Muslim female presented with moderate anaemia, mild jaundice and hepatosplenomegaly with no history of blood transfusion in the past. Routine examination was suggestive of haemolytic jaundice. High pressure liquid chromatography (HPLC) electrophoresis of the patient's blood showed haemoglobin (Hb) SD disease. As it is a double heterozygous disease, family screening was done. It showed that the father was sickle cell trait. Mother was Hb D trait. Both the brothers were sickle cell trait and the only sister was normal. Hb SD disease is a very rare variety of haemoglobinopathy and the case is presented here due to its rarity.

Hereditary spherocytosis coexisting with UDP-glucuronosyltransferase deficiency highly suggestive of Crigler-Najjar syndrome type II

Patients with co-existing hereditary spherocytosis (HS) and UDP-glucuronosyltransferase 1A1 (UGT1A1) deficiency as Gilbert's syndrome (GS) have been reported, and previous studies have demonstrated an increased risk for developing gallstones in patients with co-inheritance of GS and HS. We experienced an interesting case of HS showing persistent jaundice after splenectomy, and upon further evaluation, the 25-year-old female patient was found to have HS combined with UGT1A1 deficiency. Sequence analysis of the UGT1A1 gene revealed that she was a compound heterozygote with p.[G71R; Y486D] + [Y486D] mutations, which suggests Crigler-Najjar syndrome type II rather than GS. Careful evaluation of inappropriately elevated bilirubin level compared with the degree of hemolysis is important, reflecting the therapeutic implication of splenectomy and cholecystectomy.

A polymorphism near IL28B is associated with spontaneous clearance of acute hepatitis C virus and jaundice

BACKGROUND & AIMS

A single nucleotide polymorphism (SNP) upstream of the IL28B gene has been associated with response of patients with chronic hepatitis C to therapy with pegylated interferon and ribavirin and also with spontaneous clearance of acute hepatitis C in a heterogeneous population. We analyzed the association between IL28B and the clinical presentation of acute hepatitis C virus (HCV) infection in a homogeneous population.

METHODS

We analyzed the SNP rs12979860 in 190 women from the German anti-D cohort (infected with HCV genotype 1b via contaminated rhesus prophylaxis) and its association with spontaneous clearance. Clinical data were available in 136 women with acute infection who were also evaluated for IL28B genotype. Based on results of a TaqMan polymerase chain reaction assay, the rs12979860 SNP genotypes studied were C/C, C/T, or T/T.

RESULTS

Spontaneous clearance was more common in patients with the C/C genotype (43/67; 64%) compared with C/T (22/90; 24%) or T/T (2/33; 6%) (P < .001). Jaundice during acute infection was more common among patients with C/C genotype (32.7%) than non-C/C patients (with C/T or T/T) (16.1%; P = .032). In C/C patients, jaundice during acute infection was not associated with an increased chance of spontaneous clearance (56.3%) compared with those without jaundice (60.6%). In contrast, in non-C/C patients, jaundice was associated with a higher likelihood of spontaneous clearance (42.9%) compared with those without jaundice (13.7%).

CONCLUSIONS

The SNP rs12979860 upstream of IL28B is associated with spontaneous clearance of HCV. Women with the C/T or T/T genotype who did not develop jaundice had a lower chance of spontaneous clearance of HCV infection.

Identification and functional studies of two new dual-oxidase 2 (DUOX2) mutations in a child with congenital hypothyroidism and a eutopic normal-size thyroid gland

CONTEXT

Some cases of congenital hypothyroidism (CH) are associated with a gland of normal size.

OBJECTIVE

To explore the cause of organification defect in one child with CH and a eutopic thyroid gland, genetic analyses of TPO, DUOX2, and DUOXA2 genes were performed.

PATIENT

One child with CH, a eutopic thyroid gland, and a partial organification defect was shown after (123)I scintigraphy and perchlorate test.

METHODS

In the child with the organification defect, TPO, DUOX2, and DUOXA2 genes were analyzed. The functional activity of the DUOX2 mutants was studied after expression in eukaryotic cells.

RESULTS

No TPO or DUOXA2 gene mutations were identified. Direct sequencing of the DUOX2 gene revealed a compound heterozygous genotype for S911L and C1052Y substitutions. S911L and C1052Y caused a partial defect in H(2)O(2) production after transient expression in HeLa cells.

CONCLUSIONS

We performed a genetic analysis in one child with CH and a eutopic thyroid gland. Two new mutations in DUOX2 gene responsible for the partial deficit in the organification process were identified.

Seven novel mutations of the UGT1A1 gene in patients with unconjugated hyperbilirubinemia

The aim of this study was to identify new pathogenic variations of the UGT1A1 gene in 11 patients diagnosed with neonatal unconjugated hyperbilirubinemia. We describe two cases in which clinically unapparent heterozygotic mutations in the UGT1A1 gene may become evident in combination with certain environmental conditions or additional genetic defects.

Calculated in vivo free bilirubin levels in the central nervous system of Gunn rat pups

In vitro studies suggest a free bilirubin (B(F)) concentration in the range of 71-770 nmol/L can induce neurotoxicity. In vivo data regarding central nervous system (CNS) B(F) levels have not been determined. We calculated in vivo CNS B(F) levels in Gunn rat pups (15-19 d old; heterozygous nonjaundiced Gunn rats (J/j) and homozygous jaundiced Gunn rats (j/j); saline or sulfadimethoxine treated) based on 1) total brain bilirubin (TBB) content, 2) brain albumin level, 3) CNS bilirubin binding capacity attributable to brain albumin determined using an ultrafiltration technique, and 4) published Gunn rat albumin-bilirubin binding constants (k). Gunn rat brain bilirubin binding capacity was approximately 22 x 10(-3) micromol/g, of which two thirds was accounted for by brain albumin. Using a Gunn rat pup in vivo, k of 9.2 L/micromol, calculated CNS B(F) levels ranged from 72 to 112 nmol/L [95% confidence interval (CI)] in saline and from 59 to 156 nmol/L (95% CI) in sulfadimethoxine-treated J/j pups. These animals demonstrated no neurobehavioral abnormalities and normal cerebellar weight. Calculated CNS B(F) levels were severalfold higher (p < 0.001) in saline (95% CI: 556-1110 nmol/L) and sulfadimethoxine-treated (95% CI: 3461-8985 nmol/L) j/j pups; the former evidenced reduced cerebellar weight; the latter both reduced cerebellar weight and acute neurobehavioral abnormalities. We conclude that calculated CNS B(F) values in j/j pups are substantially higher than those in J/j animals. Given the absence of CNS abnormalities in J/j pups, the presence of such in j/j animals, and the CNS B(F) levels in these groups, we speculate that the CNS B(F) neurotoxicity threshold in vivo is subsumed within the range (71-770 nmol/L) reported in vitro.

Transcutaneous bilirubinometry: a noninvasive tool for studying newborn jaundiced rats before and after exposure to light

The homozygous Gunn rat is the most frequently used animal model for the study of neonatal jaundice. We evaluated the applicability of noninvasive transcutaneous bilirubin (TcB) measurements as an index of serum total bilirubin (STB) levels in neonatal rats by comparison to invasive STB measurements. TcB measurements were made during the first 96 h of life with the Model 101 Minolta/Air-Shields Jaundice Meter (JM) and SpectRx BiliCheck System (BC). Measurements with both devices displayed parallel TcB profiles, rapidly rising within 24 h, increasing during the next 6 h, then leveling off after 30 h. Linear regressions for the JM (n = 60) were as follows: STB (mg/dL) = 0.79 (JM) - 0.01 (units, r = 0.95, head); STB (mg/dL) = 0.82 (JM) + 1.51 (units, r = 0.95, upper back); and STB (mg/dL) = 0.74 (JM) + 1.60 (units, r = 0.91, lower back). Mean bias +/- imprecision were as follows: -0.02 +/- 3.99 mg/dL, -0.01 +/- 3.90, and 0.01 +/- 4.28 at the head, upper back, and lower back, respectively. For the BC, only lower back measurements were taken, and the regression was as follows: STB (mg/dL) = 0.77 (BC) + 1.65 mg/dL, (r = 0.93, n = 29) with a mean bias +/- imprecision of -1.08 +/- 3.08 mg/dL. When pups were exposed to light, correlations remained strong but intercepts increased. These results demonstrate that noninvasive TcB measurements correlate highly with STB in the Gunn rat during the first 96 h of life and after exposure to light. We conclude that JM measurements at the head and BC at the lower back reflect STB most reliably and consistently. Thus, in addition to being a useful tool for evaluating jaundice in human neonates, TcB methodology can be used successfully for the noninvasive monitoring of jaundice in neonatal Gunn rats pre- and postlight exposure.

Glucose-6-phosphate dehydrogenase deficiency and Gilbert syndrome: a gene interaction underlies severe jaundice without severe hemolysis

The authors describe the paradoxical clinical phenotype of an undetected severe hemolysis in parallel with the development of severe jaundice in a 13-year-old male suffering from a confirmed interaction of glucose-6-phosphate dehydrogenase deficiency (Mediterranean variant, 563 C/T) and Gilbert syndrome [variant (TA)7/(TA)7]. The child had 2 acute hemolytic episodes at the age of 10 and 13 years following infections of unknown origin. Both episodes were characterized by considerably high bilirubin levels (1st episode: 10.8 mg/dL, 2nd episode: 17.8 mg/dL) associated with unexpectably mild hemolysis indices (1st episode hemoglobin levels, 11.1 g/dL; reticulocyte counts, 2.5%; 2nd episode hemoglobin values, 12.7 g/dL; reticulocyte counts, 2.5%). During the steady-state condition of the child, hemoglobin values were within the normal ranges for his age (14.2 g/dL) and bilirubin levels were slightly elevated (1.70 mg/dL, indirect 1.5 mg/dL). The interaction of the two genetic abnormalities in the causation of this odd clinical phenotype is discussed.

Hyperbilirubinemia and cholelithiasis in Chinese patients with hemoglobin H disease

Hemoglobin H disease (HbH) is a hemoglobinopathy peculiar to parts of the world with high incidence alpha-thalassemia mutations. Among 90 HbH cases, 50 cases suffered from clinically significant jaundice (bilirubin >30 mmol/l), including 14 with severe jaundice (bilirubin >60 mmol/l). Cholelithiasis was found in 38 cases. The incidence is roughly eight times higher than that in background control population but 50% lower than that in beta-thalassemia. The risk of gallstones was related to higher bilirubin levels but not alpha-globin genotype, sex, ferritin, and hemoglobin levels. Homozygotes or double heterozygotes for Gilbert alleles (17.2%), but not heterozgyotes (42.2%), were found to have a significantly increased risk of gallstones and jaundice. However, common Chinese Gilbert syndrome alleles do not completely explain the variable risks.

Dual hereditary jaundice: simultaneous occurrence of mutations causing Gilbert's and Dubin-Johnson syndrome

BACKGROUND & AIMS

Dubin-Johnson syndrome is recessively inherited, conjugated hyperbilirubinemia induced by mutations in the ABCC2/MRP2 gene encoding the canalicular transporter for conjugated bilirubin. Gilbert's syndrome is recessively inherited, unconjugated hyperbilirubinemia caused by decreased conjugation rate of bilirubin associated mostly with homozygous A(TA) 7 TAA variant of the TATAA-box in the UGT1A1 gene promoter. Our aim was to establish the molecular diagnosis in a 3-year-old male with atypical, intermittent, predominantly unconjugated, hyperbilirubinemia.

METHODS

99m Tc-HIDA cholescintigraphy was used for imaging the biliary tree. Expression of ABCC2/MRP2 protein in hepatocytes was investigated immunohistochemically. UGT1A1 and ABCC2/MRP2 genes were sequenced from genomic DNA, and the mutations were verified by fragment analysis, sequencing the cloned exons, and restriction fragment length polymorphism.

RESULTS

Cholescintigraphy revealed delayed visualization of the gallbladder. A brown granular lipopigment differing from melanin-like pigment reported in Dubin-Johnson syndrome was present in hepatocytes, but, otherwise, liver histology was normal. ABCC2/MRP2 protein was not detected on the canalicular membrane of hepatocytes, and 2 novel mutations were found in the ABCC2/MRP2 gene: a heterozygous in-frame insertion-deletion mutation 1256insCT/delAAACAGTGAACCTGATG in exon 10 inherited from the father and a heterozygous deletion 4292delCA in exon 30 inherited from the mother. In addition, the patient was homozygous for -3279T>G and A(TA) 7 TAA mutations in the UGT1A1 gene promoter.

CONCLUSIONS

Our patient represents a case of digenic mixed hyperbilirubinemia-a distinct type of constitutive jaundice resulting from coinherited defects in ABCC2/MRP2 and UGT1A1 genes.

Sequence variability of human cytomegalovirus UL144 open reading frame in low-passage clinical isolates

OBJECTIVE

To explore the relationship between human cytomegalovirus (HCMV) UL144 sequence variability and clinical disease.

METHODS

HCMV UL144 open reading frame (ORF) was amplified by PCR assay in 72 low-passage isolates [65 congenitally infective children and 7 healthy children who were HCMV-DNA positive by quantitative PCR (qPCR)]. All positive PCR products were analyzed by heteroduplex mobility assay and single-stranded conformation polymorphism (HMA-SSCP) and 32 of them were sequenced.

RESULTS

Fifty-five patient isolates and five healthy children isolates were HCMV-UL144 positive by PCR. Sequencing and HMA-SSCP analysis showed that significant strain-specific variability was present in the UL144 ORF. Phylogenetic analysis indicated that the nucleotide sequences could be separated into 3 major genotypes. Comparing between UL144 sequences and the corresponding symptoms showed that genotype 2 did not exist in megacolon isolates. And genotype 1 and 3 were the major types among microcephaly and jaundice isolates respectively.

CONCLUSIONS

HCMV-UL144 existed in most of low passage isolates and sequences were hypervariable. The UL144 ORF and its predicted product with the high level of sequence variability in different kinds of isolates suggest that UL144 ORF might play a role in HCMV infectivity and subsequent diseases.

Prolonged jaundice and hypothyroidism as the presenting symptoms in a neonate with a novel Prop1 gene mutation (Q83X)

OBJECTIVE

To identify the genetic defect in a neonate presented with prolonged jaundice and central hypothyroidism.

DESIGN

Central hypothyroidism was detected in a neonate initially examined for prolonged jaundice, and levothyroxine therapy was initiated. Direct sequencing of the Prop1 gene was carried out and pituitary function and morphology were evaluated using hormonal testing and magnetic resonance imaging (MRI) respectively.

METHODS

Dynamic hormonal testing was carried out using established methodologies. Hormones were determined by RIA or chemiluminescence immunoassays. Genomic analysis of the Prop1 gene was performed by direct sequencing. MRI protocol: sagittal spin echo T2-weighted scans 2500/90 (TR/TE), plain and contrast-enhanced sagittal and coronal spin echo T1-weighted scans 500/20 (TR/TE).

RESULTS

Low thyroid hormones (coupled with lack of TSH rise), low GH, normal cortisol and normal prolactin values were detected. Direct sequencing revealed the presence of two mutations in the Prop1 gene: GA296del and Q83X. The Q83X was further confirmed by PvuII restriction digestion and represented a novel Prop1 gene mutation, which was not detected in 100 controls tested. Pituitary enlargement was detected, with respect to normal-for-age controls.

CONCLUSIONS

(i) The Q83X mutation extends the spectrum of Prop1 gene mutations; (ii) central hypothyroidism in a neonate might constitute the initial sign of Prop1 gene defect; (iii) the patient is the youngest individual with Prop1 gene defect and pituitary enlargement presented to date; and (iv) early detection of Prop1 gene mutations facilitates genetic counseling and ensures prompt management of the anticipated hormonal insufficiencies.

[Glucose-6-phosphate dehydrogenase deficiency, neonatal hyperbilirubinemia and Gilbert syndrome]

The aim of this work was to evaluate the influence of abnormal UDP-glucoronosyltransferase-1 (UGT1A1) gene variant, on the incidence and severity of neonatal hyperbilirubinemia, in glucose-6-phosphate dehydrogenase (G6PD) deficient newborns. The A(TA)nTAA region in the promoter of the UGT1A1 gene was analysed in 20 children with G6PD deficiency. Fourteen of these children had the African type variant (G6PDA-) and 6 had different variants (G6PDNara, G6PDGuadalajara, G6PDDurham, G6PDTomah, G6PDAveiro e G6PDNashville) related to chronic nonspherocytic haemolytic anaemia (CNSHA). The existence of a positive history of neonatal hyperbilirubinemia, as well as its severity was registered. The incidence of neonatal hyperbilirubinemia was increased in this group of children (90%) and was not associated with abnormal alleles of the UGT1A1 gene. It was not possible to assess the influence of abnormal alleles in the severity of the neonatal hyperbilirubinemia. However, these abnormal alleles did not account for the severity of jaundice in children who presented variants related to CNSHA, since 5 were treated with an exchange transfusion and none presented abnormal alleles.

Severe jaundice in a patient with a previously undescribed glucose-6-phosphate dehydrogenase (G6PD) mutation and Gilbert syndrome

A patient with chronic hemolytic anemia and G6PD deficiency was noted to be severely jaundiced and to have a high serum ferritin level. Analysis of his DNA revealed only heterozygosity for the c.187 C-->G (H63D) mutation of HFE, but showed that he was homozygous for the UDP glucuronosyltransferase promoter mutation of Gilbert's disease and that he had a previously undescribed mutation of G6PD, c.832 T-->C (Ser278Pro). The new variant was named G6PD La Jolla.

Forced expression of murine IL-17E induces growth retardation, jaundice, a Th2-biased response, and multiorgan inflammation in mice

IL-17 is a proinflammatory cytokine, and its in vivo expression induces neutrophilia in mice. IL-17E is a recently described member of an emerging family of IL-17-related cytokines. IL-17E has been shown to bind IL-17Rh1, a protein distantly related to the IL-17R, suggesting that IL-17E probably possesses unique biological functions. In this study, we have identified the murine ortholog of IL-17E and developed transgenic mice to characterize its actions in vivo. Biological consequences of overexpression of murine (m)IL-17E, both unique to IL-17E and similar to IL-17, were revealed. Exposure to mIL-17E resulted in a Th2-biased response, characterized by eosinophilia, increased serum IgE and IgG1, and a Th2 cytokine profile including elevated serum levels of IL-13 and IL-5 and elevated gene expression of IL-4, IL-5, IL-10, and IL-13 was observed in many tissues. Increased gene expression of IFN-gamma in several tissues and elevated serum TNF-alpha were also noted. In addition, IL-17E induces G-CSF production in vitro and mIL-17E-transgenic mice had increased serum G-CSF and exhibit neutrophilia, a property shared by IL-17. Moreover, exposure to mIL-17E elicited pathological changes in multiple tissues, particularly liver, heart, and lungs, characterized by mixed inflammatory cell infiltration, epithelial hyperplasia, and hypertrophy. Taken together, these findings suggest that IL-17E is a unique pleiotropic cytokine and may be an important mediator of inflammatory and immune responses.

Genetic determinants of jaundice and gallstones in haemoglobin E beta thalassaemia

Chronic hyperbilirubinaemia, gallstone formation, and gall bladder disease are unusually common in people with haemoglobin E beta thalassaemia in Sri Lanka. To determine whether this has a genetic basis we compared the bilirubin levels and frequency of gallstones in patients with different alleles of the UGT*1 gene. There was a significantly higher bilirubin level in those with the 7/7 genotypes compared with 6/6 and 6/7 genotype (p=0.032 and 0.0015 respectively), who also appeared more prone to gallstone formation. These results suggest that the UGT*1 genotpe is of importance in the genesis of gallstones in this population of patients.

Genes for jaundice

The inheritable causes of jaundice comprise a large group of conditions of varying frequency, from Gilbert's syndrome which is relatively common, to the very rare Crigle-Najjar syndrome. Although these conditions have been well characterized clinically and in some cases biochemically, the underlying molecular defects were unknown because of a lack of knowledge about the process of bile secretion by hepatocytes. The recent cloning of several transporters for bile acids and other organic anions has enabled a greater understanding of this process and allowed correlation of the malfunction of these genes with specific disease processes. This new knowledge will provide for precision in diagnosis, allow antenatal testing and provide opportunities for gene therapy for some of the more serious disorders.

Anomalous development of the hepatobiliary system in the Inv mouse

Extrahepatic biliary atresia (BA) is a devastating disease of the neonate in which the hepatic and/or common bile duct is obliterated or interrupted. Infants and children with this diagnosis constitute 50% to 60% of the pediatric population that undergoes orthotopic liver transplantation. However, there is still very little known about the etiology and pathogenesis of BA. Several recent studies have demonstrated that anomalies of situs determination are more commonly associated with BA than previously recognized. In this study, we examined the pathogenesis of jaundice in the inv mouse, a transgenic mouse in which a recessive deletion of the inversin gene results in situs inversus and jaundice. The results show that these mice have cholestasis with conjugated hyperbilirubinemia, failure to excrete technetium-labeled mebrofenin from the liver into the small intestine, lack of continuity between the extrahepatic biliary tree and the small intestine as demonstrated by Trypan blue cholangiography, and a liver histological picture indicative of extrahepatic biliary obstruction with negligible inflammation/necrosis within the hepatic parenchyma. Lectin histochemical staining of biliary epithelial cells in serial sections suggests the presence of several different anomalies in the architecture of the extrahepatic biliary system. These results suggest that the inversin gene plays an essential role in the morphogenesis of the hepatobiliary system and raise the possibility that alterations in the human orthologue of inversin account for some of the cases of BA in which there are also anomalies of situs determination.

Intermittent jaundice in patients with acute leukaemia: a common mutation of the bilirubin uridine-diphosphate glucuronosyltransferase gene among Asians

The Gly71Arg mutation of the hepatic bilirubin UDP glucuronosyl-transferase (B-UGT) gene associated with Gilbert syndrome prevails among Japanese and its gene frequency is 0.13. Among 20 patients with acute leukaemia, 4 patients showed intermittent unconjugated hyperbilirubinaemia during the course of combined chemotherapy. The Gly71Arg mutation was detected in all 4 patients with hyperbilirubinaemia, but was not found in 16 patients without hyperbilirubinaemia. Two of them were heterozygotes and one was a homozygote for the Gly71Arg mutation, and the other was a compound heterozygote of the Gly71Arg mutation and TA insertion mutation in the TATA box of the B-UGT gene. In addition to the complications leading to hyperbilirubinaemia, including liver damage due to drugs, viral infections or tumour cell infiltrations and alloimmune haemolysis, carrier status for the Gly71Arg mutation should be considered in a patient with leukaemia showing intermittent hyperbilirubinaemia during the course of chemotherapy, especially among Japanese, Koreans and Chinese owing to its prevalence in those populations.

Genetic testing for Gilbert's syndrome: how useful is it in determining the cause of jaundice?

Gilbert's syndrome is a benign condition causing hyperbilirubinemia, which is also a symptom of liver or hemolytic disease. A genetic test may be possible for Gilbert's syndrome because an associated gene defect has been isolated. Here we present a mathematical analysis of the use of this test in excluding harmful causes of hyperbilirubinemia. The effectiveness of the test depends on a low prevalence and high penetrance of the gene defect and a low prevalence of harmful hyperbilirubinemia. If the gene defect has a 12% prevalence and 10% penetrance, then the prevalence of harmful hyperbilirubinemia needs to be <1.5% for a positive test to reduce this risk fivefold. Estimates of the prevalence of harmful hyperbilirubinemia and of the prevalence and penetrance of the Gilbert genotype are required to assess the value of the genetic test in determining a cause of hyperbilirubinemia. Until these values for prevalence and penetrance are known, genetic testing for Gilbert's syndrome cannot be recommended on a routine basis.

Gilbert syndrome and glucose-6-phosphate dehydrogenase deficiency: a dose-dependent genetic interaction crucial to neonatal hyperbilirubinemia

Severe jaundice leading to kernicterus or death in the newborn is the most devastating consequence of glucose-6-phosphate dehydrogenase (EC 1.1.1.49; G-6-PD) deficiency. We asked whether the TA repeat promoter polymorphism in the gene for uridinediphosphoglucuronate glucuronosyltransferase 1 (EC 2.4.1.17; UDPGT1), associated with benign jaundice in adults (Gilbert syndrome), increases the incidence of neonatal hyperbilirubinemia in G-6-PD deficiency. DNA from term neonates was analyzed for UDPGT1 polymorphism (normal homozygotes, heterozygotes, variant homozygotes), and for G-6-PD Mediterranean deficiency. The variant UDPGT1 promoter allele frequency was similar in G-6-PD-deficient and normal neonates. Thirty (22.9%) G-6-PD deficient neonates developed serum total bilirubin >/= 257 micromol/liter, vs. 22 (9.2%) normals (P = 0.0005). Of those with the normal homozygous UDPGT1 genotype, the incidence of hyperbilirubinemia was similar in G-6-PD-deficients and controls (9.7% and 9.9%). In contrast, in the G-6-PD-deficient neonates, those with the heterozygous or homozygous variant UDPGT1 genotype had a higher incidence of hyperbilirubinemia than corresponding controls (heterozygotes: 31.6% vs. 6.7%, P < 0.0001; variant homozygotes: 50% vs. 14.7%, P = 0.02). Among G-6-PD-deficient infants the incidence of hyperbilirubinemia was greater in those with the heterozygous (31.6%, P = 0.006) or variant homozygous (50%, P = 0.003) UDPGT1 genotype than in normal homozygotes. In contrast, among those normal for G-6-PD, the UDPGT1 polymorphism had no significant effect (heterozygotes: 6.7%; variant homozygotes: 14.7%). Thus, neither G-6-PD deficiency nor the variant UDPGT1 promoter, alone, increased the incidence of hyperbilirubinemia, but both in combination did. This gene interaction may serve as a paradigm of the interaction of benign genetic polymorphisms in the causation of disease.

Development of cerebellar hypoplasia in jaundiced Gunn rats: a quantitative light microscopic analysis

The homozygous (ii) Gunn rat provides a model for hyperbilirubinemia which includes prominent cerebellar hypoplasia. Development of the Gunn rat cerebellum was examined with and without the additional effects of elevating brain bilirubin concentration to still higher levels via sulfadimethoxine (sulfa) administration. Homozygous (jj) Gunn rats and heterozygous (Nj) littermate controls (n = 32 each) were given 100 mg/kg sulfa or saline at postnatal days 3, 7, 17, and 30, and most were sacrificed 24 h later (n = 4 for each genotype at each age). Cerebellar volume, total volume and cell number for each deep cerebellar nucleus, densities for Purkinje and granule cells in the cerebellar cortex of lobules II, VI and IX, and the density of vacuolated Purkinje cells were all measured quantitatively. Cytoplasmic vacuolation provided an indication of bilirubin toxicity and was never observed in the Nj control rats. Vacuolated Purkinje cells were first observed in jj-saline rats at 18 days and were found only in the more anterior lobules of the cerebellum (II and VI). By contrast, vacuolated Purkinje cells were observed in jj-sulfa rats at both 4 and 8 days, but only in the most posterior cerebellar lobule (IX). In all older jj rats, the decline in vacuolation was accompanied by significant necrosis and resorption of the Purkinje cells in the anterior lobules. Since the Purkinje cells in the posterior lobules are the first to differentiate in the cerebellum and are resistant to bilirubin toxicity in jj-saline rats, the results support the presence of a critical period when elevated brain bilirubin may be most toxic to neuronal development. The findings suggest that neurons undergoing differentiation at the time of bilirubin exposure are most susceptible to cell death, while cells that are slightly more or slightly less mature may show only transient changes.

Pravastatin transport across the hepatocyte canalicular membrane requires both ATP and a transmembrane pH gradient

Hepatic excretion of non-bile acid organic anions is reported to be ATP-dependent and a defect of this transport has been reported in congenitally jaundiced rats, animal models of human Dubin-Johnson syndrome. To investigate the effect of the transmembrane pH gradient on hepatocyte canalicular membrane transport of ATP-dependent organic anions, uptake of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase-inhibiting organic anion, by hepatocyte canalicular membrane vesicles was observed in the presence or absence of transmembrane pH gradients. Uptake was assessed by a rapid filtration technique. ATP-dependent pravastatin uptake was stimulated in the presence of a transmembrane pH gradient (in > out) in Sprague-Dawley (SD) rats. Uptake was dependent on both pravastatin and ATP concentrations and showed saturation kinetics. After intravenous injection of [14C]-pravastatin (0.3 mumol), 81% of the dose was excreted in the bile within 35 min in SD rats, whereas only 20% was excreted in the bile in Eisai hyperbilirubinuria rats. ATP and the pH gradient also co-stimulated the uptake of pravastatin in Eisai hyperbilirubinuria rats, although the K(m) was much higher and Vmax was much lower than corresponding values in SD rats. This coincided well with the marked reduction in vivo biliary excretion of pravastatin in jaundiced rats.

Proline, ascorbic acid, or thioredoxin affect jaundice and mortality in Long Evans cinnamon rats

The Long Evans Cinnamon (LEC) rat spontaneously develops fulminant hepatitis, which is usually lethal due to excess copper accumulation in the liver and is considered an animal model of Wilson's disease. LEC rats show a strong appetite for proline solution. Daily oral (p.o.) administration of proline resulted in significant delay of mortality. Feeding a copper-deficient diet greatly delayed the onset of jaundice and mortality and voluntary consumption or p.o. administration of proline further delayed jaundice and prevented mortality. LEC rats also consume ascorbic acid solutions, and p.o. administration of ascorbate also results in a significant delay in the appearance of jaundice and mortality. Combined treatment with ascorbic acid and proline is additive to delay further jaundice and mortality. An endogenous antioxidant protein, thioredoxin, when infused by minipump IP, could also inhibit the incidence of jaundice. These results indicate that antioxidant treatment combined with proline may be of benefit in Wilson's disease and possibly other forms of hepatic dysfunction.

A unique bilirubin-UDP-glucuronosyltransferase deficiency related to neonatal jaundice in mice

This report describes biochemical and cellular characterization of a spontaneous mutation in ICR mice; the mutation has been phenotypically characterized as autosomal recessive jaundice in neonates and juveniles and given the gene symbol hub (J. Hered. 76:441-446, 1985; Mouse Newslett. 73:28, 1985). The results obtained demonstrate that (1) mice homozygous for the mutation are deficient in bilirubin-UDP-glucuronosyltransferase activity, and there is no deficiency in heterozygous mice, (2) the deficiency is lifelong, even though the clinical symptom of jaundice is transitory and restricted to neonates or juveniles, (3) bilirubin-UDP-glucuronosyltransferase activity in mutant and nonmutant mice is similarly induced by triiodothyronine, (4) glucuronidation and xylodation of bilirubin probably occur as the result of separate enzyme forms in mice, and (5) Western analysis using antibody to rat bilirubin-UDP-glucuronosyltransferase indicates that although there is no electrophoretic mobility difference, there is a diffuse band missing in mutant mice. Hepatic hyperplasia, cytomegaly, single-cell necrosis, and eosinophilic foci are also pleiotropic traits associated with homozygous but not heterozygous hub. The hub/hub mouse will be useful in the study of substrate specificity and regulation within a complex gene family and, perhaps, provide a new and useful animal model for the long-term health effects of deficiency in the metabolism of xenobiotics cleared via UDP-glucuronosyltransferase.

The murine mutation jaundiced is caused by replacement of an arginine with a stop codon in the mRNA encoding the ninth repeat of beta-spectrin

The jaundiced, ja/ja, mouse mutant has a severe hemolytic anemia associated with a deficiency of beta-spectrin in erythrocyte ghosts. Genes for the disease phenotype and beta-spectrin colocalize on Chromosome 12. beta-Spectrin mRNA is not detected in reticulocytes or in brain from newborn mutant mice. To locate the nucleotide sequence alteration, the erythroid beta-spectrin transcript from mutant spleen was amplified by reverse transcription PCR and sequenced. A C-to-T alteration is present in the mutant transcript and produces a premature stop codon from an arginine codon in mRNA encoding repeat 9 of beta-spectrin at amino acid position 1160. The point mutation introduces a Dde I site that is present in PCR-amplified DNA of ja/ja and ja/+ mice but not of +/+ control mice from the strain of origin, 129/Sv, or from the two strains, WB/Re and C57BL/6J, in which the mutation has been fixed by over 53 generations of backcrossing. The genetic data confirm that the point mutation is responsible for the severe reductions in beta-spectrin mRNA of jaundiced mice.

[Establishment of hyperbilirubinuria rat mutant--a new animal model for jaundice]

A new animal model for jaundice, a hyperbilirubinemic rat mutant (EHBR, Eizai hyperbilirubinuria rat), was established from Sprague-Dawley rats. Hyperbilirubinemia was inherited as an autosomal recessive trait. The gene manifesting jaundice was named "hyb". Homozygotes developed jaundice immediately after birth, and a high bilirubin concentration was detected in plasma and urine. The plasma bilirubin levels were high in the neonatal period, but they decreased from 6 to 10 weeks old. In male homozygotes, plasma bilirubin levels increased rapidly until about 40 weeks, and decreased thereafter. Female homozygotes showed slightly high plasma bilirubin levels until 56 weeks, then increased rapidly thereafter. At 72 weeks, the plasma bilirubin level of females was comparable to that of males. About 80 percent of the plasma bilirubin was conjugated. Plasma biochemistry demonstrated the increase of total cholesterol and total bile acid in the homozygotes. Histopathologically, the homozygote was characterized by brown pigment in the hepatocytes, and glomerular lesions with mesangial expansion. From these findings it was considered that EHBR might be a useful animal model for studying constitutional conjugated hyperbilirubinemia and bilirubin metabolism.

Complete nucleotide sequence of the murine erythroid beta-spectrin cDNA and tissue-specific expression in normal and jaundiced mice

Spectrin, a heterodimer of alpha and beta subunits, is an essential component of the red blood cell membrane skeleton. The jaundiced (ja/ja) mutation causes a severe hemolytic anemia in mice and is mapped to the erythroid beta-spectrin locus (Spnb-1) on chromosome 12. As a prerequisite for determining the molecular defect of the jaundiced mutation, we have cloned and sequenced the complete murine reticulocyte cDNA for normal Spnb-1. Two unique transcripts that differ in the placement of polyA tails are represented in the clones isolated. Amino acid sequence comparison between erythroid and murine brain spectrin (Spnb-2, chromosome 11) shows 67% identity throughout repeats 16 and 17 and complete divergence in domain III, which is associated with the alpha/beta subunit dimerization and phosphorylation. We examined the tissue distribution of normal and mutant erythroid beta-spectrin transcripts using domain-specific probes. Transcripts are detected in normal spleen tissue and reticulocytes (8 and 9.6 kb), brain tissue (10 and 11 kb), skeletal muscle tissue, and cardiac muscle tissue (11, 10.3, 7.2, and 4.0 kb). Extensive variability in mRNA processing is shown with region-specific probes. Steady state levels of the mutant transcripts are reduced when hybridized with a probe to repeats 2 through 6 with the exception of the 7.2-kb transcript that is unique to heart and skeletal muscle tissues, and is present at normal and elevated levels, respectively, in ja/ja mice. These results provide evidence for more diverse tissue-specific products of the Spnb-1 gene than were previously suspected.

Human UDP-glucuronosyl transferases: chemical defence, jaundice and gene therapy

Human UDP-glucuronosyltransferases (UDPGTs) are a family of enzymes which detoxify many hundreds of compounds by their conjugation to glucuronic acid, rendering them both harmless and more water soluble, hence, excretable. The level of expression of each UDPGT isoform in the body is the result of interplay between temporal, tissue-specific and environmental regulators. This complexity contributes to the difficulty in predicting the metabolic fate of compounds. Genetic defects and polymorphisms affecting individual isoform activities have deleterious and potentially lethal effects, as exemplified by the severe hyperbilirubinaemia observed in Crigler-Najjar Syndrome. Such severe genetic defects in bilirubin glucuronidation are obvious candidates for antenatal screening and gene therapy.

Changes in hepatic copper distribution leading to hepatitis in LEC rats

Copper (Cu) accumulating in the liver of LEC (Long-Evans with a cinnamon-like coat color) rats due to a hereditary metabolic disorder is assumed to cause acute hepatitis with severe jaundice or chronic hepatitis leading to cancer. Changes in concentrations and distributions of Cu, zinc and iron in the liver of LEC rats were determined to find the relationship between the chemical forms and the toxicity. Female rats after delivery were used because of high susceptibility to acute hepatitis. They were divided into four stages according to the development of jaundice. Cu concentrations in the whole liver and the supernatant decreased with development of jaundice. Distribution profiles of Cu, zinc, iron and sulfur on a gel filtration column by HPLC-ICP showed that Cu in the liver supernatant was mostly bound to metallothionein (MT) before jaundice (stage 1), high molecular weight proteins and MT at the beginning of jaundice (stages 2 and 3), and then mostly to MT at severe jaundice (stage 4) though the concentration of Cu at this stage was decreased to about 50% of stage 1. The results suggest that Cu accumulating as MT in the liver is liberated drastically after exceeding the capacity of MT synthesis, and the liberated Cu causes acute hepatitis.

Preserved organic anion transport in mutant TR- rats with a hepatobiliary secretion defect

The in vivo biliary secretion of a number of organic anions in mutant TR- rats was studied. The secretion of bilirubin glucuronide (BG), the glutathione conjugate of bromosulfophthalein, dibromosulfophthalein, and indocyanine green was reduced to 2, 15, 50, and 75% of normal, respectively. Surprisingly, the secretion of bilirubin ditaurate (BDT) was entirely normal under these conditions. In isolated TR- rat liver perfusion experiments (recirculating setup), the hepatobiliary secretion of BG and BDT was reduced to 1 and 50% of normal, respectively. There was considerable residual concentrative transport of BDT under these conditions (bile-to-perfusate concentration ratio of 190 +/- 60; normal, 730 +/- 480), whereas for BG the concentration step was completely abolished (bile-to-perfusate concentration ratio of 1.3 +/- 1.0; normal, 60 +/- 40). In a single-pass isolated TR- rat liver perfusion study, BDT secretion after bolus administration (1 mumol) was abnormal; the peak secretion was retarded to 20 min after injection (normal 7.5 min), and the secretion rate was decreased to 19% of normal. BDT, as an organic dianion, is a substrate for the "canalicular multispecific organic anion transporter" (cMOAT), a carrier protein that is defective in TR- rats. Its considerable residual secretion in certain experimental conditions suggests the preservation of a low-affinity pathway for secretion of some cMOAT substrates in TR- rats.

Study of a protein S gene polymorphism at DNA and mRNA level in a family with symptomatic protein S deficiency

A protein S gene polymorphism, detectable by restriction analysis of amplified exonic sequences, was investigated in a family with members affected by protein S deficiency, deep vein thrombosis and ictus. The clinical laboratory findings as well as RFLP analysis were consistent with the presence of a type WP III protein S deficiency clearly marked by a polymorphic allele, thus enabling us to determine the carrier status in several subjects. The RFLP analysis, extended to platelet mRNA after reverse transcription and amplification, demonstrated that the mRNA produced by the putative defective gene was present in a subject affected by thrombosis.

Granule cells and the development of synapses with mossy fibres in the cerebellum of the jaundiced Gunn rat

The development of granule cells and the formation of synapses with mossy fibres were investigated in cerebella from jaundiced (j/j) Gunn rats with hereditary hyperbilirubinemia. The external granular layer was thinner than that in cerebella from heterozygous (+/j) Gunn rats without hyperbilirubinemia on days 12 and 15 after birth, and it had disappeared in places by day 18. Migrating granule cells decreased in number from days 12 to 18. In the internal granular layer, the paucity of granule cells became apparent on day 12 and a reduction in the number of cells was prominent from day 18 onward. More degenerating cells were found in j/j cerebella than in +/j cerebella on days 12 and 15. Mossy fibre-granule cell synapses (glomeruli) were immature in appearance in j/j and +/j cerebella from days 7 to 12; small, roundish mossy fibre terminals were in contact with a few dendrites of granule cells. After day 18, the glomeruli were mature in terms of shape in +/j cerebella. By contrast, the mossy terminals remained small and roundish, and the granule cell dendrites that surrounded the mossy terminals did not increase in number nor develop digitiform branches in j/j cerebella. The mossy terminals were partially surrounded by glial processes and were occasionally surrounded by large dendrites of Golgi cells, which made multiple synaptic contacts. Some degenerating mossy terminals were present from days 18 to 30. These anomalous glomeruli may be caused by insufficient synaptic contacts with granule cells.

Accumulation of organic anion in intracellular vesicles of cultured rat hepatocytes is mediated by the canalicular multispecific organic anion transporter

Transport of organic anions within hepatocytes and the possible involvement of intracellular vesicles were studied with fluorescence microscopy. For this purpose monochlorobimane, a nonfluorescent hydrophobic compound that readily permeates into cells and is conjugated with glutathione to form the fluorescent glutathione bimane, was used. In the isolated perfused livers of normal rats, glutathione bimane is rapidly secreted into bile. In contrast, in our study of livers from mutant TR- rats, a 100-fold reduction in glutathione bimane secretion into bile occurred. Mutant TR- rats have an inherited defect in the canalicular multispecific organic anion transporter, which mediates the ATP-dependent secretion of a wide range of organic anions over the canalicular membrane into bile. When cultured Wistar and TR- hepatocytes were loaded with glutathione bimane, both cell types displayed a strong cytosolic fluorescence. Wistar cells completely lost this cytosolic fluorescence at incubation on monochlorobimane-free medium because of secretion of glutathione bimane. A clear punctate fluorescence remained, however, which was scattered through the cell with some perinuclear concentration. In some cells vesicular fluorescence was also concentrated around a canaliculus. In contrast, TR- cells lost their cytosolic fluorescence more slowly and completely lacked the vesicular fluorescence. Making cells selectively permeable with digitonin directly after loading them with glutathione bimane to remove cytosolic fluorescence again revealed the presence of fluorescent vesicles in Wistar cells and their absence in TR- cells. In Wistar cells vesicular fluorescence could be increased by preincubation with monensin or methylamine, compounds that have been shown to interfere with plasma membrane recycling. In conclusion, these results suggest that apart from secretion over the plasma membrane, the canalicular multispecific organic anion transporter may be involved in accumulation of organic anion in intracellular vesicles. It is hypothesized that this intracellular localization of the canalicular multispecific organic anion transporter is caused by recycling of the transporter between the plasma membrane and intracellular membranes.

Copper-metallothionein induction in the liver of LEC rats

Recently, copper (Cu) was found to be unusually accumulated, suggesting the induction of metallothionein (MT) in the liver of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis. Thus, the direct relationship between the unusual Cu accumulation and the induction of Cu-MT was investigated by giving LEC rats Cu-overloaded or Cu-deficient diets. Results based on the determinations of Cu and MT levels in several organs, as well as the gel-filtration profiles of the cytosols of liver homogenates, showed that dietary Cu induced Cu-MT and development of hepatic injury associated with jaundice.

Auditory nerve of the normal and jaundiced rat. II. Frequency selectivity and two-tone rate suppression

This study is the continuation of the functional probing of the auditory periphery in the normal and jaundiced rat. Threshold tuning curves from normal rat auditory nerve fibers were comparable to those reported in other mammals. Life-long unconjugated hyperbilirubinemia does not appear to have a widespread, demonstrable effect on cochlear frequency selectivity and sensitivity as measured by the shapes of FTCs of single auditory nerve fibers. Most fibers from the jj Gunn rats had threshold tuning curves as sharp as those from control animals (Jj Gunn and Long-Evans). Any difference seems to lie in a greater threshold variability, particularly for the high-SR fibers, for the Gunn rat strain. Two-tone rate suppression, particularly above CF, was detected in most fibers from the three groups of rats. The optimal suppression frequency (SF) as a function of CF displayed the same progression. Suppression thresholds at any given CF were generally higher for high-SR fibers than for low-SR fibers for all three groups of animals.

Pathological and laboratory findings in LEC/Otk rats that spontaneously develop hepatic injury

The LEC strain of rats that spontaneously develops hepatic injury has been introduced into specific pathogen-free (SPF) conditions (SPF-LEC/Otk). The present communication describes the clinical and pathological features of the SPF-LEC/Otk rats. The characteristic features of these animals are as follows: (i) Jaundice develops in almost all rats with increase in the P-GPT level; (ii) The animals show episodes of jaundice, a high P-GPT level and liver cell necrosis, but only slight inflammatory cell infiltration; (iii) The liver cells show characteristic microvesicular fatty changes; (iv) The P-GPT level shows increases, first at 18 weeks and then at 25 weeks of age; (v) The rats show immunological disorders, such as deficiency of immunoglobulins, especially IgG1, and of helper T cells; (vi) Infectious agents such as viruses do not seem to be involved, although this possibility cannot be absolutely excluded; (vii) The immunological disorders are not directly associated with the occurrence of liver cell necrosis; and (viii) The pattern of inheritance (autosomal single-recessive trait) of the disease strongly suggests that it is due to a genetic metabolic disorder.

A difference in mortality between two strains of jaundiced rats

Homozygous Gunn rats lack bilirubin glucuronyltransferase, become jaundiced, and often develop kernicterus, thus providing a model for neonatal hyperbilirubinemia. Two new, inbred rat strains that carry the Gunn mutation are described. These were developed by breeding the mutant Gunn gene (j) into the RHA/N and ACI/N strains, producing the new lines, which were designated RHA/N-j and ACI/N-j. Liver assay confirmed the absence of transferase activity in jaundiced rats from both of the new strains, but marked differences in mortality between the strains were observed. The mortality of jaundiced RHA/N-j rats through 8 weeks was the same as that of their nonjaundiced littermates (20%). In contrast, mortality of jaundiced ACI/N-j rats was distinctly greater than that of their nonjaundiced littermates (81% vs 34%, P less than .001). Signs of kernicterus such as ataxia were much more frequent in jaundiced ACI/N-j rats than in jaundiced RHA/N-j rats (73% vs 11%, P less than .001). Both strains had comparable albumin concentrations through 8 weeks of age. Serum bilirubin concentrations were also comparable, except for a small but significant difference at 20 days of age (ACI/N-j = 294 mumols/L, RHA/N-j = 248 mumols/L, P less than .01). Similarly, the bilirubin-to-albumin ratios were comparable except for a significantly higher ratio at 20 days of age in the ACI/N-j rats (ACI/N-j = 0.70, RHA/N-j = 0.51, P less than .01). Thus, the RHA/N-j strain is unusual in that the jaundiced animals remain healthy. Conversely, the ACI/N-j animals demonstrate a high incidence of kernicterus with mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

High-performance liquid chromatographic analysis of bile pigments as their native tetrapyrroles and as their dipyrrolic azosulfanilate derivatives

A reversed-phase high-performance liquid chromatographic (HPLC) analysis of bile pigments is described that provides baseline separation of the major bilirubin conjugates found in bile. The advantage of the technique is that the bile pigments can be analyzed directly as their native tetrapyrroles without prior solvent extractions or derivatization. The use of ammonium acetate in place of sodium salts permits preparative isolation and lyophilization of the pigments for mass spectroscopy. The derivatization of the pigments as their dipyrrolic azosulfanilates with subsequent HPLC analysis demonstrates baseline separation of the endo- and exovinyl azodipyrroles and allows identification of that half of the tetrapyrrole which contains the conjugate in the instances of monoglycosides.

Beta 0-thalassemia due to a nonsense mutation at beta 90 (GAG----TAG) in human hemoglobin gene

We studied a patient with severe anemia and jaundice who exhibited a high hemoglobin A1 (HbA1) level secondary to an increase in HbF despite normal glucose tolerance. The red blood cells showed anisocytosis, poikilocytosis and polychromasia; target cells, Howell-Jolly bodies, Heints bodies and punctate basophilia were observed. No defect or reduction in activity was observed in 19 red cell enzymes. A family history of similar anemia in the patient's daughter and cousins on the mother's side indicated an involvement of genetic factors. Gene cloning and DNA analysis showed that the condition is a new type of beta 0-thalassemia caused by a nonsense mutation (GAG----TAG) in codon 90 of the beta-globin gene.