Histopathological findings from the investigation of paediatric acute hepatitis of unknown aetiology, United Kingdom 2022.

In 2022, there were global reports of increased numbers of acute hepatitis not explained by hepatitis A-E virus infection in children. This manuscript summarises histopathology results from 20 patients in the United Kingdom who underwent liver transplant or had a liver biopsy as part of aetiological investigations. All available histopathological samples were reviewed centrally as part of the outbreak investigation. A working group comprised of infection specialists, hepatologists and histopathologists met virtually to review the cases, presentation, investigations and histopathology. All 20 liver samples had evidence of inflammation without significant interface activity, and submassive confluent pan-lobular or multilobular hepatocellular necrosis. Overall, the predominant histopathological findings were of acute nonspecific hepatitis with submassive hepatic necrosis and central vein perivenulitis and endothelitis. Histopathological findings were a poor indicator of aetiology.

Outbreak of indeterminate acute liver failure in children with adenoviraemia - Not a new disease.

BACKGROUND & AIMS: In the year 2022, an outbreak of indeterminate acute hepatitis and indeterminate paediatric acute liver failure (ID-PALF) in association with adenoviraemia in immunocompetent children was reported in the UK. We postulate that this association is not a new disease in immunocompetent children. METHODS: Children with acute hepatitis during the outbreak who were referred to King's College Hospital, London for advice and management were included in the study. Data on the frequency of ID-PALF in 2022, as well as transplantation rates and the association with adenovirus infection, were obtained from electronic health records. The clinical presentation, histology and outcomes of children with ID-PALF and adenoviraemia in 2017-2021 were compared with those in 2022. RESULTS: From January to June 2022, 65 patients with acute hepatitis were referred. Ten children were admitted with ID-PALF. ID-PALF constituted 26% of all PALF cases in 2017-2021, in contrast to 58.8% during the 2022 outbreak. During the outbreak, adenoviraemia was present in 52% of children with acute hepatitis without liver failure (in whom adenoviraemia test results were available) and in 100% of ID-PALF cases. Adenoviraemia was seen in immunocompetent children in 6/13 (46%) of all ID-PALF cases between 2017-2019, with a clear absence of adenoviraemia in the 6 ID-PALF cases during 2020-2021. Compared to ID-PALF with adenoviraemia in 2017-2019 (n = 6), ID-PALF with adenoviraemia during the outbreak (n = 10) was associated with more frequent hepatic encephalopathy, hypotension requiring vasoactive medications and higher plasma ammonia levels (admission and peak), with similar native liver survival. CONCLUSIONS: The recent outbreak of ID-PALF with adenoviraemia in immunocompetent children does not appear to be a new disease, contrary to perception and other reports. The frequency of such cases over the years could be linked to background rates of adenovirus infections. IMPACT AND IMPLICATIONS: Indeterminate paediatric acute liver failure (ID-PALF) associated with adenoviraemia in immunocompetent children is not a new disease specific to 2022. The exclusive role of human adenovirus infection in the causation of this outbreak of acute hepatitis seems unlikely. Indeed, we provide histological data from explants in transplanted patients that do not support direct viral cytotoxicity. The disease is probably mediated by immunological injury directed towards adenovirus infection and/or adeno-associated virus-2.

Acute hepatitis of unknown aetiology in children: a clinical update on the recent outbreak with mechanistic insights.

Since April 2022, over 1000 children across 35 countries have developed episodes of acute hepatitis of unknown origin. At King's College Hospital, a total of 65 children were referred with acute hepatitis of unknown etiology, with 10 of these children presenting with acute liver dysfunction leading to acute liver failure. Multiple hypotheses have been proposed and continue to be investigated worldwide. In this review, we explore the current understanding of potential aetiologies for this outbreak. We further characterize the proposed immunological mechanisms of liver injury in these cases.

Hepatic Dry Copper Weight in Pediatric Autoimmune Liver Disease.

OBJECTIVES: Elevated hepatic dry copper weight is recognized in adults with autoimmune liver disease (AILD) and chronic cholestasis. We aim to review hepatic dry copper weight in pediatric AILD. METHODS: Retrospective review of pediatric AILD managed at our institution from 1999 to 2018, and 104 patients with hepatic dry copper weight assessment were included. RESULTS: Median age at presentation was 13.4 years (interquartile range, IQR, 11.7-14.9), 60% female, 54% autoimmune hepatitis, 42% autoimmune sclerosing cholangitis, and 4% primary sclerosing cholangitis. Histological features of advanced liver fibrosis in 68%. Median hepatic dry copper weight was 51.1 µg/g dry weight (IQR, 28.0-103.8). Elevated hepatic dry copper weight (>50 µg/g dry weight) was present in 51%, and was not associated with AILD subtype ( P = 0.83), age at presentation ( P = 0.68), or advanced fibrosis ( P = 0.53). Liver transplantation (LT) was performed in 10%, who had higher hepatic dry copper weight (148.5 µg/g dry weight [IQR, 39.5-257.3] vs 47.5 [IQR, 27.8-91.5], P = 0.04); however this was not associated with LT on multivariate analysis (hazard ratio 1.002, 95% CI 0.999-1.005, P = 0.23). In 8 (7.7%) patients ATP7B was sequenced and potentially disease causing variants were identified in 2 patients, both who required LT. CONCLUSIONS: Elevations in hepatic dry copper weight are common in pediatric AILD. Unlike in adults, it is not associated with AILD subtypes with cholestasis. Higher dry copper weight was detected in patients who required LT. While further work is needed to identify the significance of copper deposition in pediatric AILD, we recommend close monitoring of patients with elevated levels for progressive liver disease.

Two cases of DCDC2-related neonatal sclerosing cholangitis with developmental delay and literature review.

Ciliopathies are a group of clinical and molecular heterogeneous conditions with pleiotropic manifestations affecting the central nervous system, renal, liver, skeletal, and ocular systems. Biallelic pathogenic variants in DCDC2 cause a ciliopathy primarily presenting with neonatal sclerosing cholangitis (NSC). Pathogenic variants in DCDC2 have further been reported in the context of nephronophthisis and non-syndromic recessive deafness. Polymorphisms in DCDC2 have also been associated with dyslexia and DCDC2 has a role in neuronal development. We report on two unrelated patients with DCDC2-related NSC with additional central nervous system impairment manifesting as microcephaly, global developmental delay, and axial hypotonia. Histological findings of our patients can mimic biliary atresia or congenital hepatic fibrosis. We further show that transmission electron microscopy in patients with NSC does not always show absence of primary cilia. Hence patients with DCDC2 pathogenic variants should also undergo an evaluation of neuromotor development. Review of all reported patients further reveals a risk for supra-aortic arterial aneurysms.

Cholestasis Due to USP53 Deficiency.

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.

Seamless Management of Juvenile Autoimmune Liver Disease: Long-Term Medical and Social Outcome.

OBJECTIVES: To report baseline features and long-term medical/social outcomes of juvenile autoimmune liver disease, including autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC), managed in a single tertiary center. STUDY DESIGN: Retrospective study of children diagnosed in 2000-2004 with AIH/ASC followed up to date. Patients with abnormal cholangiogram were classified as ASC. Presentation and outcome features were compared. RESULTS: Eighty-three children were included (42 female, median age 12.1 years [8.5-14.1 years], AIH = 54, ASC = 29). Most (65%) had antinuclear and/or anti-smooth muscle autoantibodies; 6% presented with acute liver failure; 29% had histologic evidence of cirrhosis. The 1999 and simplified International Autoimmune Hepatitis Group criteria failed to diagnose up to 26% of patients with AIH and 48% with ASC, and the proposed the European Society for Pediatric Gastroenterology, Hepatology and Nutrition criteria were accurate. Response to treatment was excellent with 95% achieving normal transaminase levels. During follow-up, 31% had at least 1 relapse episode; 3 patients with AIH developed cholangiopathy and 5 patients with ASC developed progressive bile duct injury. At last follow-up (median of 14.5 years, 10.4-16.8), 99% were alive, 11 underwent transplantation and 1 is listed for transplant. Five-, 10-, and 15-year transplant-free survival rates were 95%, 88%, and 83%; patients with ASC and those relapsing being more likely to require transplant. Social outcome was excellent with 93% in employment/education. CONCLUSIONS: Seamless management of juvenile autoimmune liver disease leads to excellent clinical and social outcomes. Despite good response to immunosuppressive treatment, patients with ASC have a worse prognosis than those with AIH. Diagnostic models developed for adults are unsatisfactory to correctly diagnose juvenile autoimmune liver disease.

Mutations in Myosin 5B in Children With Early-onset Cholestasis.

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 55 µmol/L (2-500), alanine aminotransferase 73I IU/L (32-114), γ-glutamyltransferase 7 IU/L (7-10), and serum bile acids 134 µmol/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.

Chronic Cholangiopathy Associated with Primary Immune Deficiencies Can Be Resolved by Effective Hematopoietic Stem Cell Transplantation.

OBJECTIVES: To investigate effects and outcome of hematopoietic stem cell transplantation (HSCT) on sclerosing cholangitis, in pediatric patients with different primary immunodeficiencies (PIDs). STUDY DESIGN: From databases in 2 tertiary centers for immunodeficiencies and liver disease, we have identified children with PIDs and sclerosing cholangitis, who have paired clinical, radiologic, and histologic information before and after HSCT and studied their clinical progress and outcome. RESULTS: Seven of 13 children (53.8%) died at a median interval of 4 months (range, 3 months-5 years) after HSCT. However, 6 surviving children (46.2%) with different PIDs and less severe cholangiopathies showed an improvement in markers of liver injury within months of successful unrelated reduced intensity conditioning HSCT. The repeated native liver biopsy, performed in 4 patients at a median of 96 (range, 4-144) months post-HSCT, showed a considerable improvement. Biochemical markers of liver function in the survivors completely normalized after a median of 13 months (range, 2-48). All patients continue to have a mildly dilated extrahepatic biliary system on ultrasonography with no intrahepatic ductal changes on magnetic resonance cholangiography after a follow-up of median 18 years (range, 2-20). CONCLUSIONS: Effective HSCT has the potential to improve biochemical and histologic features of cholangiopathy in children with PIDs, presumably by clearance of chronic infection following establishment of immune competence. However, careful patient selection is critical as advanced liver injury is often associated with serious complications and mortality.

Autoimmune pancreatitis in children: A single centre experience in diagnosis, management and long term follow up.

OBJECTIVES: Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis and data is limited in the paediatric population. We aim to describe in detail a cohort of paediatric patients with AIP including their presentation, investigations that led to their diagnosis, management and long-term follow up. METHODS: We retrospectively reviewed the data of 6 patients diagnosed with AIP over an 10-year period. Data including demographics, clinical information, laboratory parameters, serological markers, radiological and histological findings as well as longitudinal follow up were collected. RESULTS: Out of the six patients, one was diagnosed with definitive Type 1 AIP, two with definitive Type 2 AIP, two with probable Type 2 AIP and one with suspected Type 2 AIP. Median time of follow up was 3.9 years (range 2.6-10.1). 4 patients had pancreatic biopsies with 2 of these patients showing granulocytic epithelial lesions (GELs). 4 patients received steroids and two of them developed ulcerative colitis. Azathioprine was commenced on the patient with Type 1 AIP to help her wean off steroids that caused significant side effects on her. Only two patients developed exocrine insufficiency. CONCLUSIONS: The long term follow up of our cohort of paediatric AIP shows good prognosis. More follow up data on patients with AIP is needed to help further characterize and define the disease.

Liver neoplasms in methylmalonic aciduria: An emerging complication.

Methylmalonic aciduria (MMA) is an inherited metabolic disease caused by methylmalonyl-CoA mutase deficiency. Early-onset disease usually presents with a neonatal acute metabolic acidosis, rapidly causing lethargy, coma, and death if untreated. Late-onset patients have a better prognosis but develop common long-term complications, including neurological deterioration, chronic kidney disease, pancreatitis, optic neuropathy, and chronic liver disease. Of note, oncogenesis has been reported anecdotally in organic acidurias. Here, we present three novel and two previously published cases of MMA patients who developed malignant liver neoplasms. All five patients were affected by a severe, early-onset form of isolated MMA (4 mut0 , 1 cblB subtype). Different types of liver neoplasms, that is, hepatoblastoma and hepatocellular carcinoma, were diagnosed at ages ranging from infancy to adulthood. We discuss pathophysiological hypotheses involved in MMA-related oncogenesis such as mitochondrial dysfunction, impairment of tricarboxylic acid cycle, oxidative stress, and effects of oncometabolites. Based on the intriguing occurrence of liver abnormalities, including neoplasms, we recommend close biochemical and imaging monitoring of liver disease in routine follow-up of MMA patients.

Paediatric fatty liver disease (PeFLD): All is not NAFLD - Pathophysiological insights and approach to management.

The recognition of a pattern of steatotic liver injury where histology mimicked alcoholic liver disease, but alcohol consumption was denied, led to the identification of non-alcoholic fatty liver disease (NAFLD). Non-alcoholic fatty liver disease has since become the most common chronic liver disease in adults owing to the global epidemic of obesity. However, in paediatrics, the term NAFLD seems incongruous: alcohol consumption is largely not a factor and inherited metabolic disorders can mimic or co-exist with a diagnosis of NAFLD. The term paediatric fatty liver disease may be more appropriate. In this article, we summarise the known causes of steatosis in children according to their typical, clinical presentation: i) acute liver failure; ii) neonatal or infantile jaundice; iii) hepatomegaly, splenomegaly or hepatosplenomegaly; iv) developmental delay/psychomotor retardation and perhaps most commonly; v) the asymptomatic child with incidental discovery of abnormal liver enzymes. We offer this model as a means to provide pathophysiological insights and an approach to management of the ever more complex subject of fatty liver.

Reduced Hepatocellular Expression of Canalicular Transport Proteins in Infants with Neonatal Cholestasis and Congenital Hypopituitarism.

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.

Liver transplantation for neonatal-onset citrullinemia.

Citrullinemia or ASS deficiency in its classical form presents in the neonatal period with poor feeding, hyperammonemia, encephalopathy, seizures, and if untreated can be fatal. Despite advances in medical therapy, neurocognitive outcomes remain suboptimal. LT has emerged as a potential management option. A retrospective single-center review identified 7 children with a median age of 1.1 years (range, 0.6-5.8) at referral. Five children presented clinically, and 2 were treated prospectively from birth due to positive family history. All patients received standard medical and dietary therapy prior to LT. The indications for LT were frequent metabolic decompensations in 4, elective in 2, and ALF in 1. The median age at LT was 2.4 years (range, 1.3-6.5). Five patients received 6 left lateral segment grafts, one a live unrelated donor left lateral segment as an APOLT graft, and one a cadaveric whole liver graft as APOLT. One child required retransplantation due to hepatic artery thrombosis. Graft and patient survival were 86% and 100%, respectively. Median follow-up is 3.1 years (range, 0.1-4.1), and the median age at follow-up is 5.5 years (range, 4.0-9.8). There have been no metabolic decompensations in 6 children, while 1 patient (with APOLT) developed asymptomatic hyperammonemia with no clinical or histological signs of liver injury, requiring additional medical therapy. Our medium-term experience following LT in citrullinemia is favorable, demonstrating a positive transformation of the clinical phenotype.

The management of childhood liver diseases in adulthood.

An increasing number of patients with childhood liver disease survive into adulthood. These young adults are now entering adult services and require ongoing management. Aetiologies can be divided into liver diseases that develop in young adults which present to adult hepatologists i.e., biliary atresia and Alagille syndrome or liver diseases that occur in children/adolescents and adults i.e., autoimmune hepatitis or Wilson's disease. To successfully manage these young adults, a dynamic and responsive transition service is essential. In this review, we aim to describe the successful components of a transition service highlighting the importance of self-management support and a multi-disciplinary approach. We will also review some of the liver specific aetiologies which are unique to young adults, offering an update on pathogenesis, management and outcomes.

Autoimmune Liver Disease in Children with Sickle Cell Disease.

OBJECTIVE: To assess the incidence, clinical features, and outcome of autoimmune liver disease (AILD) in patients with sickle cell disease (SCD). STUDY DESIGN: Single center retrospective review of patients with SCD with AILD referred between 1999 and 2015. RESULTS: Thirteen of 77 (17%) patients with SCD with hepatic dysfunction were diagnosed with AILD (median age 11, range, 3.4-16 years) with a female preponderance (77%). Acute hepatitis and insidious onset were the commonest presentations. Two patients (15%) presented with acute liver failure. In 2 patients (15%), parvovirus B19-induced transient red cell aplasia preceded the diagnosis of AILD. All patients were positive for antinuclear and/or smooth muscle autoantibodies. Six of 12 patients (50%) had cholangiopathy on cholangiogram suggesting autoimmune sclerosing cholangitis (ASC). Liver biopsy, performed in 11 patients without complications, showed interface hepatitis in 90%. Patients with AILD were treated with standard immunosuppression. After a median follow-up of 3.8 years (range, 0.2-14.3), 10 patients are alive (1 was transplanted 6.4 years after diagnosis); 2 are lost to follow-up; 1 died of subdural hemorrhage before starting treatment for AILD. Five (42%) achieved full and 4 (33%) partial biochemical remission. Ulcerative colitis, present in 4 patients (2 male patients, 3 with ASC) was diagnosed in 2 patients before and in 2 patients after the diagnosis of AILD. CONCLUSIONS: AILD is not uncommon in patients with SCD, affecting mainly female patients and responding satisfactorily to immunosuppressive treatment. Liver biopsy is helpful in confirming the diagnosis and can be safely performed in the absence of acute vaso-occlusive sickling episodes. Ulcerative colitis is common in the presence of ASC.

Prematurity and biliary atresia: a 30-year observational study.

AIM OF STUDY: The diagnosis of biliary atresia (BA) remains challenging and delay can lead to significant morbidity with time to surgery a key factor in determining outcome. Prematurity may impact on outcome potentially delaying diagnosis. We sought to assess whether the premature BA infants (PBA) have a delayed time to surgery and as such, worse outcomes? METHODS: Review of a single-centre prospectively maintained database. Prematurity was defined as delivery < 37/40 gestation. PBA was compared with date-matched term biliary atresia controls on a 2:1 basis. Primary outcomes were clearance of jaundice (< 20 µmol/L) and native liver survival. A retrospective assessment of liver fibrosis was made on biopsies at diagnosis and at Kasai portoenterostomy (KPE) in both premature and term cohorts. Data are quoted as median (range) unless indicated. A P value of ≤ 0.05 was considered statistically significant. RESULTS: 21 (female n = 14, 67%) premature infants with BA were treated in the period Jan. 1988-Dec. 2016 and compared with 41 contemporaneous term BA controls. Median gestation was 33 (29-36) weeks and birth weight 1930 (948-4230)g. Twin pregnancy (n = 10) was the leading cause for prematurity and significantly higher than the controls (48 vs. 0%; P < 0.0001). Maternal co-morbidity was high (n = 10, 48%) including pre-eclampsia (19%) and diabetes (14%). Liver biopsy was performed in 19 (90%) patients (all diagnostic) at a median of 57 (4-266) days. Delayed diagnosis (> 50 days) was seen in n = 13 but not associated with parenteral nutrition use (46 vs. 33%, P = 0.59) or phototherapy (50 vs. 83%, P = 0.19). Both BASM (33 vs. 7.5%; P = 0.01) and duodenal atresia (19 vs. 0%; P = 0.01) were seen more frequently in the PBA cohort. Mean fibrosis scores (Ishak) from diagnostic biopsies were lower in the premature group than the control group (2.71 vs. 3.53, P = 0.043) indicating less fibrosis but this equalized by time of subsequent KPE (P = 0.17). Primary surgery was Kasai portoenterostomy (n = 20) at an older median age than controls (65 vs. 56 days; P = 0.06). Liver transplantation was the primary procedure in one late-presenting child. There was an increased but non-significant clearance of jaundice in the PBA group [n = 12/20 (60%) vs 20/41 (48%); P = 0.23] post-KPE. Native liver survival and true survival were not different (P = 0.58 and 0.23). CONCLUSIONS: PBA infants have similar outcomes to term infants, despite delayed diagnosis and higher frequency of the syndromic form. The high incidence of discordant twins supports the theory that epigenetic modifications could contribute to the pathogenesis of BA. LEVEL OF EVIDENCE: IIIc Retrospective Matched Cohort Study.

Mutations in DCDC2 (doublecortin domain containing protein 2) in neonatal sclerosing cholangitis.

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.