Specific expression of hepatitis B surface antigen (HBsAg) in transgenic mice.

Two transgenic mice were obtained that contain in their chromosomes the complete hepatitis B virus (HBV) genome except for the core gene. These mice secrete particles of HBV surface antigen (HBsAg) in the serum. In one mouse, HBV DNA sequences that had integrated at two different sites were shown to segregate independently in the first filial generation (F1) and only one of the sequences allowed expression of the surface antigen. Among these animals the males produced five to ten times more HBsAg than the females. A 2.1-kilobase messenger RNA species comigrating with the major surface gene messenger RNA is expressed specifically in the liver in the two original mice. The results suggest that the HBV sequences introduced into the mice are able to confer a tissue-specific expression to the S gene. In addition, the HBV transgenic mice represent a new model for the chronic carrier state of hepatitis B virus infection.

Structure and expression of hcr, a locus rearranged with c-myc in a woodchuck hepatocellular carcinoma.

We have previously described a rearrangement of the proto-oncogene c-myc with a new cellular sequence of unknown function in a woodchuck primary liver tumor. We have now cloned and further analysed the normal woodchuck locus (termed hcr) of the sequence involved in the rearrangement with c-myc. The hcr locus is highly expressed in hepatocytes but not in other cell types examined and is conserved in mammals. Two unspliced hcr transcripts 4.5 and 4.7 kb long accumulate in liver cell nuclei. These transcripts differ only in their 3' extremities, located 180 bases apart, and by additional poly(A) tailing of the longer RNA species. The genomic sequence flanking the transcription start site contains variant elements of a classical eukaryotic promoter. Nucleotide sequence analysis of cDNA clones for the hcr RNA reveals that the 5' end of the hcr transcripts contains a short open reading frame of only 3 gamma codons initiated by an ATG. The biological function of her RNA remains to be determined.

Fifteen novel mutations in the JAGGED1 gene of patients with Alagille syndrome.

Mutations in the human JAGGED1 gene cause Alagille syndrome, an autosomal dominant developmental disorder. The gene encodes a transmembrane protein which is a ligand of Notch receptors. We report 23 mutations in previously undescribed probands, including 15 novel mutations and 8 recurrent mutations. They map in the part of the gene encoding the extracellular part of the protein. Fifteen mutations are frameshifts and 8 are point mutations. They could give rise to truncated proteins (18/23, including 5 nonsense mutations). There are 2 splice defects, and the 3 missense mutations all cause loss or creation of cysteine residues in the Delta-Serrate-Lag2 domain or in EGF repeats. The inheritance was studied in 14 families, including those of 2 probands previously studied. Two mutations were transmitted from the father and 3 from the mother. Nine mutations were de novo, further confirmation that the majority of cases are sporadic.

Jagged1 mutations in alagille syndrome.

We have summarized data on 233 Alagille syndrome patients reported with mutations in Jagged1 (JAG1). This data has been published by seven different laboratories in Europe, the United States, Australia, and Japan. Mutations have been demonstrated in 60-75% of patients with a clinically confirmed diagnosis of Alagille syndrome. Total gene deletions have been reported in 3-7% of patients, and the remainder have intragenic mutations. Seventy two percent (168/233) of the reported mutations lead to frameshifts that cause a premature termination codon. These mutations will either lead to a prematurely truncated protein, or alternatively, nonsense mediated decay might lead to lack of a product from that allele. Twenty three unique missense mutations were identified (13% of mutations). These were clustered in conserved regions at the 5' end of the gene, or in the EGF repeats. Splicing consensus sequence changes were identified in 15% of patients. A high frequency of de novo mutations (60-70%) has been reported. The spectrum of mutations identified is consistent with haploinsufficiency for JAG1 being a mechanism for Alagille syndrome.

Mapping of microsatellite markers in the Alagille region and screening of microdeletions by genotyping 23 patients.

Alagille syndrome (AGS) has been assigned to 20p11.23-20p12.2 according to minimum overlap between deletions observed on the chromosome 20 short arm of 9 patients. We report here the localisation of 5 microsatellite markers (D20S41, D20S48, D20S50, D20S56, and D20S58) within the deletion of one AGS patient. This study allows an estimation of the genetic extent of this deletion as being between 30 and 36 cM, and demonstrates its paternal origin. The search for submicroscopic deletions in 23 AGS patients, by typing these 5 markers, failed to reveal allelic loss. However, these results lead to the proposition that the AGS locus lies in one of the seven intervals defined by the six microsatellite markers in the region flanked by D20S5 and D20S18.

A new family of genes and pseudogenes potentially expressing testis- and brain-specific leucine zipper proteins in man and mouse.

We have characterized a new mouse gene highly transcribed in the testis, and a derived intronless gene expressed in the embryo. The latter gene is present in Mus musculus domesticus and in Mus musculus castaneus but is absent in Mus spretus. The sequencing of different clones from a testis cDNA library reveals a complex transcriptional regulation for the intron-containing gene. The use of several promoters, alternative splicing and trans-splicing, and of two different polyadenylation sites account for the diversity. The different cDNAs encode proteins with features of basic helix-loop-helix leucine zipper (bHLH-ZIP) DNA-binding factors with homology to a new brain-specific factor. The presence of multiple CK2 and PKC phosphorylation sites suggests that their activity may be regulated by phosphorylation. In man, a pseudogene, apparently derived from the same transcript as in mouse and showing 90% homology in the coding region, is present within an intron of another gene. Interestingly, although the human pseudogene is highly mutated in human, in the mouse it has only four nucleotide changes compared with the cDNA of origin, and is still capable of encoding a protein.

Liver transplantation in children with Alagille syndrome--a study of twelve cases.

Cholestasis associated with Alagille syndrome may, in a few cases, be extremely severe and result in major impairment in the quality of life during early childhood and end up in cirrhosis eventually. We report the results of liver transplantation in 12 children with a severe hepatic form of Alagille syndrome. All children presented with cholestatic jaundice from birth, peculiar facies, stenosis of the peripheral pulmonary artery, and posterior embryotoxon; butterfly-like vertebrae were present in 9 children. At the time of transplantation (mean age 7 years 10 months) refractory pruritus was present in 9 children, xanthoma in 11, and height and weight retardation in 11. Total serum bilirubin ranged from 116 to 322 mumol/L and total serum cholesterol from 3.5 to 29 mmol/L. Systolic right ventricular pressure was moderately raised (36 to 48 mmHg) in 5 children; mean creatinine clearance was 99 ml/min/1.73 m2. Histologic examination of the removed livers showed cirrhosis, severe annular fibrosis, and moderate portal fibrosis in 4 children each. Follow-up in the 11 survivors has ranged from 14 months to 5 1/2 years. All lead normal lives. Pruritus and xanthomas disappeared. Increase in height was observed in 8 of the 10 survivors who had growth retardation prior to transplantation. School level is normal in 4 (median age at LT: 5 yr 9 mo) and below normal in 6 (median age at OLT: 9 yr 9 mo). Liver function tests are normal in 10 children. Mean creatinine clearance is 101 ml/min/1.73 m2. These results indicate that the quality of life can be considerably improved after liver transplantation in children with a severe hepatic form of Alagille syndrome and suggest that it could be carried out before these children attend elementary school.

Alpha1-antitrypsin deficiency and liver disease in children: phenotypes, manifestations, and prognosis.

Among 424 children with liver disease, 20 had alpha1-antitrypsin deficiency associated with protease inhibitor ZZ phenotype. This disorder manifested itself as cholestasis in early infancy in 19 children. Jaundice and pruritus cleared in 16 of these by 7 months of age, but hepatomegaly and laboratory evidence of mild hepatic dysfunction persisted in all. Biliary cirrhosis and portal hypertension eventually developed or was suspected in eight, and hypoplasia of intraheptic bile ducts was demonstrated in another four. Routine screening revealed intermediate alpha1-antitrypsin deficiency in 16 other children with various types of liver disease. The phenotype in these patients was MZ, MS, or SZ. PAS-positive granules were present in liver of all patients with the ZZ phenotype and in none with other phenotypes. The findings indicate that manifestations and prognosis of this inherited liver disease are extremely variable.

Alagille syndrome. The widening spectrum of arteriohepatic dysplasia.

Alagille syndrome was described more than 35 years ago as a genetic entity characterized by five major features: chronic cholestasis resulting from paucity of interlobular bile ducts, peripheral pulmonary stenosis, butterflylike vertebral arch defect, posterior embryotoxon, and peculiar facies. Recently, JAGGED1 has been identified as a responsible gene by demonstration of mutations in AGS patients. Studies of the JAGGED1 expression pattern demonstrate that minor features and almost all the elements in the long list of manifestations described in AGS patients are not coincidental. This finding suggests that the definition of AGS may be reconsidered in the light of JAGGED1 mutations.

Reduced ratio of portal tracts to paucity of intrahepatic bile ducts.

The syndrome of "paucity" of intrahepatic bile ducts is characterized by a reduction of the ratio of interlobular bile ducts to portal areas. The present unidirectional study of liver biopsy specimens in cases of so-called intrahepatic biliary atresia, controlled essentially by age-matched autopsy control, showed that there is also a reduced number of portal areas in the livers of these subjects. This fact suggests an injury to the vascular anlage associated with biliary injury.

Paucity of interlobular bile ducts.

Paucity of interlobular bile ducts (PIBD) is defined as the reduction in the number of interlobular bile ducts. Paucity could be defined using the ratio of the number of portal tracts devoid of bile duct to the total number of portal tracts. At least 10 complete portal areas must be examined. In the past, only wedge biopsies could provide such samples, but now it can be achieved with needle biopsy. Usually, two types of PIBD, syndromatic and nonsyndromatic, are considered. In the syndromatic type, paucity is a major feature of the disease. In the nonsyndromatic type, paucity is only a part of the disease, as in peroxisomal disorders or alpha 1-antitrypsine (A1AT) deficiency, and is an inconstant finding. Opacification of the intrahepatic bile ducts in infants with nonsyndromatic paucity with no associated disorder demonstrates sclerosing cholangitis in at least half of patients in whom the diagnosis of "idiopathic paucity" would have been made a few years ago. The remaining patients must be considered as waiting for the identification of new disorders associated with paucity.

[Course of chronic hepatitis related to B virus in children. Study of serum viral DNA]. / Evolution des hépatites chroniques liées au virus B chez l'enfant. Etude de l'ADN viral sérique.

Nineteen children with chronic hepatitis related to the hepatitis B virus were followed for an average of 6 years. The determination of the hepatitis B virus DNA in the serum allowed us to know the state of viral replication. Thus three groups of patients could be defined: the first in which replication remained active during the total period of follow-up; the second in which the extinction of replication was observed; the third in which replication was inactive from the beginning of the serological follow-up. Symptoms, high levels of aminotransferases and histologically aggressive lesions, sometimes with cirrhosis, were more frequent in the presence of viral DNA. During the decrease of the replication, a clear-cut and time-limited increase of serum-aminotransferase levels was often noted. After the disappearance of hepatitis B virus DNA in the serum, clinical signs could be found only in children with cirrhosis or hepatocellular carcinoma. Four cases of hepatitis with initial aggressive lesions led to persistent chronic hepatitis without viral DNA in the serum. In all but one of the patients who started with an aggressive form, viral DNA disappeared in the serum. This loss occurred later and only in 2 patients of 5 who presented initially with chronic persistent hepatitis. Thus a long period of follow-up in childhood chronic hepatitis related to B virus shows frequent inactivation of viral replication. This evolution seemed to occur earlier when the initial histological lesions were aggressive as if this aggressiveness favored the elimination of the virus and the presence of specific antibodies in the serum.(ABSTRACT TRUNCATED AT 250 WORDS)

[Acute viral hepatitis in children]. / Hépatites virales aiguës de l'enfant.

In children with acute hepatitis the main concern is to identify the cause since prognosis and therefore management largely depend on the specific causative agent. Since HAV is the most frequent in children, it should be investigated first. If there are no IGM anti-HAV antibodies, hepatitis B should be investigated. The value of anti-HCV antibodies, during acute hepatitis is not clear. Whatever the virus, severe evolution may occur, and symptoms of poor significance must be detected early. There is no risk of chronic evolution for hepatitis A. Follow-up studies of patients with hepatitis B should be performed to ensure clearance of HBSAg or to recognize the development of a chronic carrier state. Preventive measures include a search for a chronic carrier in the family and vaccination of the negative sibling or parents. In infancy, the diagnosis of "neonatal hepatitis" must be asserted by the presence of serological markers of viral infection. In the absence of such markers, other causes of cholestasis in infancy must be investigated. Perinatal transmission of hepatitis B virus should be now prevented by screening for women from high-risk groups and administration of immunoglobulins and vaccine to the neonates.

[Congenital disorders of the biliary ducts]. / Maladies congénitales des voies biliaires.

Congenital disorders of the bile ducts manifesting as neonatal cholestasis, are: biliary atresia, Alagille syndrome and neonatal sclerosing cholangitis. Biliary atresia must be considered as a neonatal surgical emergency: diagnosis and therapeutic intervention should be completed before one month of age. Survival at 10 years is about 70%, 14% without and 56% with liver transplantation. The cause of the disease is unknown. Alagille syndrome is defined by the association of bile duct paucity, pulmonary stenosis, butterfly-like vertebrae, peculiar facies and posterior embryotoxon. JAGGEDI gene mutations have been identified allowing prenatal diagnosis. The diagnosis of neonatal sclerosing cholangitis can only be performed by cholangiography.