RESUMEN
OBJECTIVES: Biallelic variants in the adenosine triphosphate binding cassette subfamily B member 4 (ABCB4) gene which encodes the multidrug resistance 3 protein (MDR3) leads to progressive familiar intrahepatic cholestasis type 3. However, monoallelic variants are increasingly recognized as contributing to liver disease in adults. Our aim was to describe the clinical characteristics of MDR3 heterozygous variants in a large cohort of infants and children with cholestatic liver disease. METHODS: The clinical and genotypic data on pediatric patients seen at King's College Hospital, London, between 2004 and 2022 and found to harbour heterozygous variants in ABCB4 were reviewed. RESULTS: Ninety-two patients amongst 1568 tested were identified with a monoallelic variant (5.9%). The most common presenting problem was conjugated hyperbilirubinemia (n = 46; 50%) followed by cholelithiasis (n = 12; 13%) and cholestatic hepatitis (n = 10; 11%). The median values of liver biochemistry at presentation were: GGT 105 IU/L and total bilirubin 86 µmol/L. Thirty-two genetic variants were identified including 22 missense (69%), 4 deletions (13%), 5 splice site (16%) and 1 termination (3%). At a median follow up of 1 year there was resolution of liver disease. CONCLUSIONS: Rare variants in ABCB4 were found amongst infants and children with cholestatic liver disease. The presenting problems were variable and abnormalities tended to normalize over time. Those with severe mutations could develop liver disease later in life when exposed to further insult and should be counseled appropriately.
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Miembro 4 de la Subfamilia B de Casete de Unión a ATP , Colestasis Intrahepática , Colestasis , Adulto , Niño , Humanos , Lactante , Colestasis/genética , Colestasis Intrahepática/genética , Colestasis Intrahepática/metabolismo , Heterocigoto , Mutación , Miembro 4 de la Subfamilia B de Casete de Unión a ATP/genéticaRESUMEN
OBJECTIVE: To use next generation sequencing (NGS) technology to identify undiagnosed, monogenic diseases in a cohort of children who suffered from acute liver failure (ALF) without an identifiable etiology. STUDY DESIGN: We identified 148 under 10 years of age admitted to King's College Hospital, London, with ALF of indeterminate etiology between 2000 and 2018. A custom NGS panel of 64 candidate genes known to cause ALF and/or metabolic liver disease was constructed. Targeted sequencing was carried out on 41 children in whom DNA samples were available. Trio exome sequencing was performed on 4 children admitted during 2019. A comparison of the clinical characteristics of those identified with biallelic variants against those without biallelic variants was then made. RESULTS: Homozygous and compound heterozygous variants were identified in 8 out of 41 children (20%) and 4 out of 4 children (100%) in whom targeted and exome sequencing were carried out, respectively. The genes involved were NBAS (3 children); DLD (2 children); and CPT1A, FAH, LARS1, MPV17, NPC1, POLG, SUCLG1, and TWINK (1 each). The 12 children who were identified with biallelic variants were younger at presentation and more likely to die in comparison with those who did not: median age at presentation of 3 months and 30 months and survival rate 75% and 97%, respectively. CONCLUSIONS: NGS was successful in identifying several specific etiologies of ALF. Variants in NBAS and mitochondrial DNA maintenance genes were the most common findings. In the future, a rapid sequencing NGS workflow could help in reaching a timely diagnosis and facilitate clinical decision making in children with ALF.
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Secuenciación de Nucleótidos de Alto Rendimiento , Fallo Hepático Agudo/diagnóstico , Fallo Hepático Agudo/genética , Niño , Preescolar , Estudios de Cohortes , Femenino , Humanos , Lactante , Recién Nacido , Fallo Hepático Agudo/mortalidad , MasculinoRESUMEN
OBJECTIVES: Although a number of genetic forms of cholestasis have been identified, the genetic etiology of disease remains unidentified in a subset of cholestasis patients. METHODS: Whole exome sequencing (WES) was performed in DNA from patients diagnosed with cholestasis, at different points on the continuum from progressive familial intrahepatic cholestasis to benign recurrent intrahepatic cholestasis, in whom no disease mutations in known cholestasis genes had been identified. Candidate genes were then assessed in a larger patient sample, by targeted next-generation sequencing (NGS). Disease features at presentation and follow-up were collected from available medical records. RESULTS: By WES, we identified 3 patients with homozygous mutations in USP53. Screening of USP53 in a larger set of patients identified 4 additional patients with homozygous mutations in USP53. Six of the 7 patients had deletion mutations, and 1 had a missense mutation; 3 of the patients were siblings, all bearing a deletion that also disrupted neighboring MYOZ2. Age of onset ranged from early infancy to adolescence. Cholestasis tended to be biochemically mild and intermittent, and responsive to medication. Liver fibrosis was, however, present in all 4 patients who were biopsied, and splenomegaly was apparent in 5 of 7 at last ultrasound. CONCLUSIONS: Two groups recently identified patients with liver disease and mutation in USP53. We have now identified biallelic mutation in USP53 in 7 further patients with cholestasis, from 5 families. Most individuals had evidence of chronic liver disease, and long-term follow-up is recommended.
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Colestasis Intrahepática , Colestasis , Proteasas Ubiquitina-Específicas/deficiencia , Adolescente , Proteínas Portadoras , Niño , Preescolar , Colestasis/genética , Colestasis Intrahepática/diagnóstico , Colestasis Intrahepática/genética , Homocigoto , Humanos , Lactante , Proteínas Musculares , Mutación , Proteasas Ubiquitina-Específicas/genética , Secuenciación del ExomaRESUMEN
OBJECTIVES: Mutations in Myosin 5B (MYO5B) are known to be associated with microvillous inclusion disease (MVID) a genetic cause of neonatal intractable diarrhoea. More recently, they have been reported in children with cholestasis but without typical gastrointestinal symptoms of MVID. We describe our series of children with cholestasis and mutations in MYO5B. METHODS: Clinical, laboratory, and histological data were collected from patients with cholestasis and pathogenic mutations in MYO5B, found by next generation sequencing (NGS) but with minimal gastrointestinal disease. RESULTS: Six patients (3 boys) were identified. Median age at presentation was 19 months (range, 3-92). Presenting features were jaundice, pale stools, pruritus, and failure to thrive. Patients 5 and 6 had intractable diarrhoea until the age of 3 and 7 years, respectively, but currently are on full enteral diet with no intestinal symptoms. Median values for serum total bilirubin were 55âµmol/L (2-500), alanine aminotransferase 73I IU/L (32-114), γ-glutamyltransferase 7âIU/L (7-10), and serum bile acids 134âµmol/L (18-274). Three patients underwent 1 or more types of biliary diversion for symptom control. Median follow-up was 5 years (2-22). At most recent follow-up, they all reported pruritus while on antipruritics. Patient 1 had a liver transplant. CONCLUSIONS: We identified 6 patients, with mutations in MYO5B, early-onset cholestasis and pruritus, with variable response to biliary diversion without typical MVID.
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Colestasis Intrahepática , Colestasis , Mucolipidosis , Niño , Preescolar , Colestasis/genética , Colestasis Intrahepática/diagnóstico , Colestasis Intrahepática/genética , Femenino , Humanos , Recién Nacido , Masculino , Microvellosidades , Mutación , Cadenas Pesadas de Miosina , Miosina Tipo V , MiosinasRESUMEN
OBJECTIVE: To assess whether prolonged neonatal cholestasis, described in congenital hypopituitarism and septo-optic dysplasia (SOD), is associated with altered expression of selected canalicular ectoenzymes and canalicular transport proteins. STUDY DESIGN: Children with congenital hypopituitarism (n = 21), SOD (n = 18), and cholestasis seen in our center over 26 years were reviewed. Histopathologic findings in archival liver biopsy specimens were assessed (n = 10) and in those with low/normal levels of serum γ-glutamyltransferase (GGT) activity despite conjugated hyperbilirubinemia, expression of canalicular ectoenzymes and canalicular transport proteins was evaluated immunohistochemically. RESULTS: Patients presented at a median age of 8 weeks (range 3-20 weeks) with median total bilirubin 116 µmol/L (45-287 µmol/L), GGT 95 IU/L (25-707 UI/L), and serum cortisol 51 nmol/L (17-240 nmol/L). All but 3 had low free thyroxin (median 9.6 pmol/L [6.8-26.9]) with increased thyroid-stimulating hormone levels (median 5.95 mU/L [<0.1-9.24]). Liver histologic features included moderate-to-severe intralobular cholestasis with nonspecific hepatitis, giant-cell transformation of hepatocytes, and fibrosis. In all, immunohistochemical staining for canalicular ectoenzymes and canalicular transport proteins revealed a degree of reduced expression, associated with normal serum GGT values in 6 of the 10 patients, and another 6 nonbiopsied infants with cholestasis also had low/normal serum GGT activity. Sequencing of ABCB11 and ATP8B1 performed in 6 of the biopsied patients did not identify pathogenic mutations. Following replacement therapy, biochemical evidence of hepatobiliary injury resolved in all children within a median period of 6 months. CONCLUSION: Hepatobiliary involvement in congenital hypopituitarism associated with SOD has a good prognosis, but its etiology remains uncertain. Immunohistochemical expression of canalicular transport proteins was reduced in available liver samples.
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Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/biosíntesis , Transportadoras de Casetes de Unión a ATP/biosíntesis , Colestasis Intrahepática/metabolismo , Hepatocitos/metabolismo , Hipopituitarismo/metabolismo , gamma-Glutamiltransferasa/biosíntesis , Biomarcadores/metabolismo , Biopsia , Colestasis Intrahepática/diagnóstico , Femenino , Hepatocitos/patología , Humanos , Hipopituitarismo/congénito , Inmunohistoquímica , Lactante , Recién Nacido , Masculino , Estudios RetrospectivosRESUMEN
BACKGROUND & AIMS: Neonatal sclerosing cholangitis (NSC) is a severe neonatal-onset cholangiopathy commonly leading to liver transplantation (LT) for end-stage liver disease in childhood. Liver biopsy findings histopathologically resemble those in biliary atresia (BA); however, in NSC extrahepatic bile ducts are patent, whilst in BA their lumina are obliterated. NSC is commonly seen in consanguineous kindreds, suggesting autosomal recessive inheritance. METHODS: From 29 NSC patients (24 families) identified, DNA was available in 24 (21 families). Thirteen (7 male) patients (12 families) of consanguineous parentage were selected for whole exome sequencing. Sequence variants were filtered for homozygosity, pathogenicity, minor allele frequency, quality score, and encoded protein expression pattern. RESULTS: Four of 13 patients were homozygous and two were compound heterozygous for mutations in the doublecortin domain containing 2 gene (DCDC2), which encodes DCDC2 protein and is expressed in cholangiocyte cilia. Another 11 patients were sequenced: one (with one sibling pair) was compound heterozygous for DCDC2 mutations. All mutations were protein-truncating. In available liver tissue from patients with DCDC2 mutations, immunostaining for human DCDC2 and the ciliary protein acetylated alpha-tubulin (ACALT) showed no expression (n=6) and transmission electron microscopy found that cholangiocytes lacked primary cilia (n=5). DCDC2 and ACALT were expressed in NSC patients without DCDC2 mutations (n=22). Of the patients carrying DCDC2 mutations, one died awaiting LT; five came to LT, of whom one died 2years later. The other 4 are well. CONCLUSION: Among 24 NSC patients with available DNA, 7 had mutations in DCDC2 (6 of 19 families). NSC patients in substantial proportion harbour mutations in DCDC2. Their disease represents a novel liver-based ciliopathy. LAY SUMMARY: Neonatal sclerosing cholangitis (NSC) is a rare genetic form of liver disease presenting in infancy. Through next generation sequencing we identified mutations in the gene encoding for doublecortin domain containing 2 (DCDC2) protein in a group of NSC children. DCDC2 is a signalling and structural protein found in primary cilia of cholangiocytes. Cholangiocytes are the cells forming the biliary system which is the draining system of the liver.
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Colangitis Esclerosante/genética , Proteínas Asociadas a Microtúbulos/genética , Mutación , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Recién Nacido , MasculinoRESUMEN
According to the most recent WHO classification of hepatocellular adenomas, a small percentage of inflammatory hepatocellular adenomas presents with mutation in the beta-catenin gene and are at higher risk of malignant transformation. It has been recognized that adenoma-like hepatocellular neoplasms with focal atypia, or in unusual clinical context present with similar cytogenetic and immunohistochemistry characteristics to well-differentiated hepatocellular carcinomas. We report a case of a well-differentiated hepatocellular neoplasm with Dubin-Johnson-like pigment displaying histological features overlapping with a beta-catenin mutated inflammatory adenoma and a well-differentiated hepatocellular carcinoma in a non-cirrhotic liver. The patient was a 48-year-old woman, who was asymptomatic, and had a clinical history of intra-uterine exposure to diethylstilbestrol, previous cancers and past oral contraceptive use. The recently proposed term "well-differentiated hepatocellular neoplasm of uncertain malignant potential" should be applied in such cases to highlight the different pathogenesis and risk of malignancy compared to the typical adenomas, and to suggest a careful and customized clinical management.
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Pigmentos Biliares/análisis , Biomarcadores de Tumor/análisis , Carcinoma Hepatocelular/genética , Diferenciación Celular , Neoplasias Hepáticas/genética , Mutación , beta Catenina/genética , Biopsia , Carcinoma Hepatocelular/química , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/cirugía , Análisis Mutacional de ADN , Femenino , Predisposición Genética a la Enfermedad , Hepatectomía , Humanos , Neoplasias Hepáticas/química , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/cirugía , Persona de Mediana Edad , FenotipoAsunto(s)
Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/genética , Atresia Biliar/cirugía , Colestasis Intrahepática/genética , Trasplante de Hígado/efectos adversos , Complicaciones del Embarazo/genética , Adulto , Biopsia , Colestasis Intrahepática/sangre , Colestasis Intrahepática/diagnóstico , Colestasis Intrahepática/tratamiento farmacológico , Femenino , Glucocorticoides/uso terapéutico , Humanos , Hígado/patología , Metilprednisolona/uso terapéutico , Mutación , Embarazo , Complicaciones del Embarazo/sangre , Complicaciones del Embarazo/diagnóstico , Complicaciones del Embarazo/tratamiento farmacológicoRESUMEN
Variants in ATP8B1, ABCB11, and ABCB4 underlie the most prevalent forms of progressive familial intrahepatic cholestasis. We aim to describe variants in these genes in a cohort of patients with adult-onset liver disease, and explore a genotype-phenotype correlation. Patients with onset of liver disease aged above 18 who underwent sequencing of cholestasis genes for clinical purposes over a 5-year period were identified. Bioinformatic analysis of variants was performed. Liver histology was evaluated in patients with variants. Of the 356 patients tested, at least one variant was identified in 101 (28.4%): 46 ABCB4, 35 ABCB11, and 28 ATP8B1. Patients with ABCB4 variants had chronic liver disease (71.7%) and pregnancy-associated liver dysfunction (75%), with a younger age of onset in more severe genotypes (p = 0.046). ABCB11 variants presented with pregnancy-associated liver dysfunction (82.4%) and acute/episodic cholestasis (40%), with no association between age of onset and genotype severity. ATP8B1 variants were associated with chronic liver disease (75%); however, they were commonly seen in patients with an alternate etiology of liver disease and variants were of low predicted pathogenicity. In adults with suspected genetic cholestasis, variants in cholestasis genes were frequently identified and were likely to contribute to the development of liver disease, particularly ABCB4 and ABCB11. Variants were often in heterozygous state, and they should no longer be considered recessive Mendelian traits. Sequencing cholestasis genes in selected patients with adult-onset disease should be considered, with interpretation in close collaboration with histopathologists and geneticists.
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Colestasis Intrahepática , Colestasis , Subfamilia B de Transportador de Casetes de Unión a ATP , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP/genética , Adenosina Trifosfatasas/genética , Colestasis/genética , Colestasis Intrahepática/epidemiología , Femenino , Heterocigoto , Humanos , Fenotipo , EmbarazoRESUMEN
Mutations in the transaldolase 1 (TALDO1) gene have been described in a limited number of cases. Several organs can be affected and clinical manifestations are variable, but often include liver dysfunction and/or hepatosplenomegaly. We report 4 patients presenting with liver disease: 2 with early-onset hepatocellular carcinoma (HCC). Patients with cholestasis and mutations in TALDO1 were identified by next-generation sequencing. Clinical, laboratory, and histological data were collected. Four (1 male) patients were identified with variants predicted to be damaging in TALDO1. Three patients were homozygous (two protein truncating/one missense mutations), 1 one was compound heterozygous (two missense mutations). Median age at presentation was 4 months (range, 2-210 days) with jaundice (3), hepatosplenomegaly (3), and pancytopaenia (1). The diagnosis was corroborated by detection of minimal transaldolase enzyme activity in skin fibroblasts in two cases and raised urine polyols in the third. Three patients underwent liver transplantation (LT), 2 of whom had confirmed HCC on explanted liver. One patient suddenly died shortly after LT. The nontransplanted case has a chronic liver disease with multiple dysplastic liver nodules, but normal liver biochemistry and alpha-fetoprotein. Median follow-up was 4 years (range, 1-21). Conclusion: Transaldolase deficiency can include early-onset normal gamma-glutamyltransferase liver disease with multisystem involvement and variable progression. Patients with this disease are at risk of early-onset HCC and may require early LT.
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Errores Innatos del Metabolismo de los Carbohidratos , Carcinoma Hepatocelular , Neoplasias Hepáticas , Transaldolasa , Carcinoma Hepatocelular/genética , Femenino , Humanos , Lactante , Recién Nacido , Neoplasias Hepáticas/genética , Masculino , Mutación , Transaldolasa/genéticaRESUMEN
BACKGROUND: Functioning farnesoid X receptor (FXR; encoded by NR1H4) is key to normal bile acid homeostasis. Biallelic mutations in NR1H4 are reported in a few children with intrahepatic cholestasis. We describe a boy with progressive familial intrahepatic cholestasis and homozygous mutation in NR1H4. CASE SUMMARY: A boy had severe neonatal cholestasis with moderate hypercholanemia and persistently elevated alpha-fetoprotein. Despite medical treatment, coagulopathy was uncontrollable, prompting liver transplantation at age 8 mo with incidental splenectomy. The patient experienced catch-up growth with good liver function and did not develop allograft steatosis. However, 1 year after transplant, he died from an acute infection, considered secondary to immunosuppression and asplenia. A homozygous protein-truncating mutation, c.547C > T, p.(Arg183Ter), was subsequently identified in NR1H4, and both parents were shown to be heterozygous carriers. Absence of FXR and of bile salt export pump expression was confirmed by immunostaining of explanted liver. CONCLUSION: Severe cholestasis with persistently high alpha-fetoprotein and modest elevation of serum bile acid levels may suggest FXR deficiency. Some patients with FXR deficiency may not develop allograft steatosis and may respond well to liver transplantation.
RESUMEN
BACKGROUND & AIMS: Progressive familial intrahepatic cholestasis (PFIC) with normal serum levels of gamma-glutamyltranspeptidase can result from mutations in ATP8B1 (encoding familial intrahepatic cholestasis 1 [FIC1]) or ABCB11 (encoding bile salt export pump [BSEP]). We evaluated clinical and laboratory features of disease in patients diagnosed with PFIC, who carried mutations in ATP8B1 (FIC1 deficiency) or ABCB11 (BSEP deficiency). Our goal was to identify features that distinguish presentation and course of these two disorders, thus facilitating diagnosis and elucidating the differing consequences of ATP8B1 and ABCB11 mutations. METHODS: A retrospective multi-center study was conducted, using questionnaires and chart review. Available clinical and biochemical data from 145 PFIC patients with mutations in either ATP8B1 (61 "FIC1 patients") or ABCB11 (84 "BSEP patients") were evaluated. RESULTS: At presentation, serum aminotransferase and bile salt levels were higher in BSEP patients; serum alkaline phosphatase values were higher, and serum albumin values were lower, in FIC1 patients. Elevated white blood cell counts, and giant or multinucleate cells at liver biopsy, were more common in BSEP patients. BSEP patients more often had gallstones and portal hypertension. Diarrhea, pancreatic disease, rickets, pneumonia, abnormal sweat tests, hearing impairment, and poor growth were more common in FIC1 patients. Among BSEP patients, the course of disease was less rapidly progressive in patients bearing the D482G mutation. CONCLUSIONS: Severe forms of FIC1 and BSEP deficiency differed. BSEP patients manifested more severe hepatobiliary disease, while FIC1 patients showed greater evidence of extrahepatic disease.
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Transportadoras de Casetes de Unión a ATP/genética , Adenosina Trifosfatasas/deficiencia , Adenosina Trifosfatasas/genética , Colestasis Intrahepática/diagnóstico , Colestasis Intrahepática/genética , Mutación , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP , Transportadoras de Casetes de Unión a ATP/metabolismo , Adolescente , Adulto , Edad de Inicio , Ácidos y Sales Biliares/metabolismo , Niño , Preescolar , Colestasis Intrahepática/metabolismo , Diagnóstico Diferencial , Progresión de la Enfermedad , Femenino , Humanos , Lactante , Recién Nacido , Estimación de Kaplan-Meier , Masculino , Fenotipo , Embarazo , Estudios Retrospectivos , Adulto Joven , gamma-Glutamiltransferasa/sangreRESUMEN
Bile salt export pump (BSEP) deficiency is a hereditary cholestatic syndrome that results from mutations in the ABCB11 (ATP-binding cassette B11) gene. Severely affected patients develop end-stage liver disease in the first decade of life. Liver transplantation has traditionally been thought of as curative for BSEP disease. We describe the clinical course of 6 patients who developed recurrent low gamma-glutamyl transpeptidase cholestasis, that mimicks BSEP disease, following transplantation. All had documented genetic defects in ABCB11 that were predicted to lead to a congenital absence of BSEP protein. The time to development of recurrence was variable; 4 underwent repeat liver transplantation for complications of recurrent disease and all 4 again developed recurrent disease after retransplantation. Siblings of these patients who also underwent liver transplantation for BSEP disease have not developed "recurrent" disease. Three of the patients with "recurrent" disease ultimately died, 2 as a direct result of complications of their liver disease.
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Transportadoras de Casetes de Unión a ATP/genética , Colestasis/epidemiología , Colestasis/cirugía , Trasplante de Hígado , Mutación/genética , gamma-Glutamiltransferasa/deficiencia , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP , Niño , Preescolar , Colestasis/genética , Genotipo , Humanos , Lactante , Recurrencia , Estudios Retrospectivos , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
UNLABELLED: The gene encoding the human bile salt export pump (BSEP), ABCB11, is mutated in several forms of intrahepatic cholestasis. Here we classified the majority (63) of known ABCB11 missense mutations and 21 single-nucleotide polymorphisms (SNPs) to determine whether they caused abnormal ABCB11 pre-messenger RNA splicing, abnormal processing of BSEP protein, or alterations in BSEP protein function. Using an in vitro minigene system to analyze splicing events, we found reduced wild-type splicing for 20 mutations/SNPs, with normal mRNA levels reduced to 5% or less in eight cases. The common ABCB11 missense mutation encoding D482G enhanced aberrant splicing, whereas the common SNP A1028A promoted exon skipping. Addition of exogenous splicing factors modulated several splicing defects. Of the mutants expressed in vitro in CHO-K1 cells, most appeared to be retained in the endoplasmic reticulum and degraded. A minority had BSEP levels similar to wild-type. The SNP variant A444 had reduced levels of protein compared with V444. Treatment with glycerol and incubation at reduced temperature overcame processing defects for several mutants, including E297G. Taurocholate transport by two assessed mutants, N490D and A570T, was reduced compared with wild-type. CONCLUSION: This work is a comprehensive analysis of 80% of ABCB11 missense mutations and single-nucleotide polymorphisms at pre-mRNA splicing and protein processing/functional levels. We show that aberrant pre-mRNA splicing occurs in a considerable number of cases, leading to reduced levels of normal mRNA. Thus, primary defects at either the protein or the mRNA level (or both) contribute significantly to BSEP deficiency. These results will help to develop mutation-specific therapies for children and adults suffering from intrahepatic cholestasis due to BSEP deficiency.
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Transportadoras de Casetes de Unión a ATP/genética , Ácidos y Sales Biliares/metabolismo , Mutación Missense , Polimorfismo de Nucleótido Simple , Precursores del ARN/genética , Empalme del ARN , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP , Animales , Células CHO , Línea Celular , Colestasis Intrahepática/genética , Cricetinae , Cricetulus , Perros , Exones , Regulación de la Expresión Génica , Humanos , Intrones , TransfecciónRESUMEN
BACKGROUND & AIMS: Patients with severe bile salt export pump (BSEP) deficiency present as infants with progressive cholestatic liver disease. We characterized mutations of ABCB11 (encoding BSEP) in such patients and correlated genotypes with residual protein detection and risk of malignancy. METHODS: Patients with intrahepatic cholestasis suggestive of BSEP deficiency were investigated by single-strand conformation polymorphism analysis and sequencing of ABCB11. Genotypes sorted by likely phenotypic severity were correlated with data on BSEP immunohistochemistry and clinical outcome. RESULTS: Eighty-two different mutations (52 novel) were identified in 109 families (9 nonsense mutations, 10 small insertions and deletions, 15 splice-site changes, 3 whole-gene deletions, 45 missense changes). In 7 families, only a single heterozygous mutation was identified despite complete sequence analysis. Thirty-two percent of mutations occurred in >1 family, with E297G and/or D482G present in 58% of European families (52/89). On immunohistochemical analysis (88 patients), 93% had abnormal or absent BSEP staining. Expression varied most for E297G and D482G, with some BSEP detected in 45% of patients (19/42) with these mutations. Hepatocellular carcinoma or cholangiocarcinoma developed in 15% of patients (19/128). Two protein-truncating mutations conferred particular risk; 38% (8/21) of such patients developed malignancy versus 10% (11/107) with potentially less severe genotypes (relative risk, 3.7 [confidence limits, 1.7-8.1; P = .003]). CONCLUSIONS: With this study, >100 ABCB11 mutations are now identified. Immunohistochemically detectable BSEP is typically absent, or much reduced, in severe disease. BSEP deficiency confers risk of hepatobiliary malignancy. Close surveillance of BSEP-deficient patients retaining their native liver, particularly those carrying 2 null mutations, is essential.
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Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Colestasis Intrahepática/genética , ADN de Neoplasias/genética , Familia , Miembro 11 de la Subfamilia B de Transportador de Casetes de Unión al ATP , Alelos , Neoplasias de los Conductos Biliares/epidemiología , Neoplasias de los Conductos Biliares/etiología , Conductos Biliares Intrahepáticos , Carcinoma Hepatocelular/epidemiología , Carcinoma Hepatocelular/etiología , Colangiocarcinoma/epidemiología , Colangiocarcinoma/etiología , Colestasis Intrahepática/complicaciones , Colestasis Intrahepática/metabolismo , Intervalos de Confianza , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Inmunohistoquímica , Incidencia , Neoplasias Hepáticas/epidemiología , Neoplasias Hepáticas/etiología , Masculino , Mutación , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , Factores de Riesgo , Análisis de Secuencia de ADN , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Partial External Biliary Diversion (PEBD) is a surgical intervention to treat children with Progressive Familial Intrahepatic Cholestasis (PFIC) and Alagille syndrome (AGS). PEBD can reduce disease progression, and examining the alterations in biliary lipid composition may be a prognostic factor for outcome. METHODS: Biliary lipid composition and the clinical course of AGS and PFIC patients were examined before and after PEBD. RESULTS: Pre-PEBD bile from AGS patients had greater chenodeoxycholic/cholic acid (CDCA/CA), bile salt, cholesterol and phospholipid concentrations than PFIC patients. AGS patients, and PFIC patients with familial intrahepatic cholestasis 1 (FIC1) genotype, responded better to PEBD than PFIC patients with bile salt export protein (BSEP) genotype. After successful PEBD, AGS patients have higher biliary lipid concentrations than PFIC patients and PEBD also increases biliary phospholipid concentrations in FIC1 patients. CONCLUSION: Both AGS and FIC1 patients can benefit from PEBD, and preserved biliary phospholipid concentrations may be associated with better outcomes post-PEBD.
Asunto(s)
Síndrome de Alagille/metabolismo , Bilis/metabolismo , Colestasis Intrahepática/metabolismo , Procedimientos Quirúrgicos del Sistema Digestivo/métodos , Metabolismo de los Lípidos/fisiología , Fosfolípidos/metabolismo , Adolescente , Síndrome de Alagille/genética , Conductos Biliares Intrahepáticos/cirugía , Biopsia , Ácido Quenodesoxicólico/metabolismo , Niño , Preescolar , Colestasis Intrahepática/genética , Colesterol/metabolismo , Ácido Cólico/metabolismo , Progresión de la Enfermedad , Vesícula Biliar/cirugía , Humanos , Lactante , Hígado/patología , Resultado del TratamientoRESUMEN
Progressive familial intrahepatic cholestasis (PFIC) with normal circulating gamma-glutamyl transpeptidase levels can result from mutations in the ATP8B1 gene (encoding familial intrahepatic cholestasis 1 [FIC1] deficiency) or the ABCB11 gene (bile salt export protein [BSEP] deficiency). We investigated the outcomes of partial external biliary diversion, ileal exclusion, and liver transplantation in these two conditions. We conducted a retrospective multicenter study of 42 patients with FIC1 deficiency (FIC1 patients) and 60 patients with BSEP deficiency (BSEP patients) who had undergone one or more surgical procedures (57 diversions, 6 exclusions, and 57 transplants). For surgeries performed prior to transplantation, BSEP patients were divided into two groups, BSEP-common (bearing common missense mutations D482G or E297G, with likely residual function) and BSEP-other. We evaluated clinical and biochemical outcomes in these patients. Overall, diversion improved biochemical parameters, pruritus, and growth, with substantial variation in individual response. BSEP-common or FIC1 patients survived longer after diversion without developing cirrhosis, being listed for or undergoing liver transplantation, or dying, compared to BSEP-other patients. Transplantation resolved cholestasis in all groups. However, FIC1 patients commonly developed hepatic steatosis, diarrhea, and/or pancreatic disease after transplant accompanied by biochemical abnormalities and often had continued poor growth. In BSEP patients with impaired growth, this generally improved after transplantation. Conclusion: Diversion can improve clinical and biochemical status in FIC1 and BSEP deficiencies, but outcomes differ depending on genetic etiology. For many patients, particularly BSEP-other, diversion is not a permanent solution and transplantation is required. Although transplantation resolves cholestasis in patients with FIC1 and BSEP deficiencies, the overall outcome remains unsatisfactory in many FIC1 patients; this is mainly due to extrahepatic manifestations. (Hepatology Communications 2018;2:515-528).
RESUMEN
An 18-year-old man underwent liver transplantation due to an Abernethy malformation associated with multiple hepatocellular nodules including one which was rapidly enlarging and was suspicious for malignant transformation. Analysis of the explanted liver showed a spectrum of multiple hepatocellular nodules ranging in appearance from focal nodular hyperplasia, hepatocellular adenoma and to a well-differentiated hepatocellular neoplasm borderline for hepatocellular carcinoma. Mutational analysis revealed wild-type ß-catenin expression in the background liver and some nodules, whilst different variants were present in other lesions irrespective of their morphological appearance. No telomerase reverse transcriptase (TERT) promoter mutation was identified. Abernethy malformations can lead to independent genetic events which can result in ß-catenin mutations associated with malignant transformation of hepatocellular nodules. When following up such patients, one must therefore have a high index of suspicion, particularly if radiological surveillance reveals a change in the nature of hepatic lesions.
Asunto(s)
Adenoma de Células Hepáticas/genética , Biomarcadores de Tumor/genética , Carcinoma Hepatocelular/genética , Hiperplasia Nodular Focal/genética , Neoplasias Hepáticas/genética , Mutación , Neoplasias Primarias Múltiples/genética , Malformaciones Vasculares/genética , beta Catenina/genética , Adenoma de Células Hepáticas/diagnóstico , Adenoma de Células Hepáticas/enzimología , Adenoma de Células Hepáticas/cirugía , Adolescente , Biomarcadores de Tumor/análisis , Biopsia , Carcinoma Hepatocelular/diagnóstico , Carcinoma Hepatocelular/enzimología , Carcinoma Hepatocelular/cirugía , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Análisis Mutacional de ADN , Hiperplasia Nodular Focal/diagnóstico , Hiperplasia Nodular Focal/enzimología , Hiperplasia Nodular Focal/cirugía , Predisposición Genética a la Enfermedad , Glutamato-Amoníaco Ligasa/análisis , Humanos , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/enzimología , Neoplasias Hepáticas/cirugía , Trasplante de Hígado , Imagen por Resonancia Magnética , Masculino , Neoplasias Primarias Múltiples/diagnóstico , Neoplasias Primarias Múltiples/enzimología , Neoplasias Primarias Múltiples/cirugía , Fenotipo , Malformaciones Vasculares/diagnóstico , Malformaciones Vasculares/enzimología , Malformaciones Vasculares/cirugíaRESUMEN
Elucidating genetic causes of cholestasis has proved to be important in understanding the physiology and pathophysiology of the liver. Here we show that protein-truncating mutations in the tight junction protein 2 gene (TJP2) cause failure of protein localization and disruption of tight-junction structure, leading to severe cholestatic liver disease. These findings contrast with those in the embryonic-lethal knockout mouse, highlighting differences in redundancy in junctional complexes between organs and species.