Simon C. Ling

Nonalcoholic Steatohepatitis in Children: A Multicenter Clinicopathological Study

Nonalcoholic fatty liver disease (NAFLD) may have distinct histological features in children and adults, but to date limited data are available on the spectrum and significance of histological lesions in pediatric patients. We conducted a multicenter study of children with well‐characterized, biopsy‐proven NAFLD to (1) assess the presence and significance of a constellation of histological lesions and (2) identify clinical and laboratory predictors of disease severity. One hundred thirty children with NAFLD seen from 1995 to 2007 in five centers in the United States and Canada were studied. Clinical and laboratory data were collected. Slides stained with hematoxylin‐eosin and trichrome were evaluated by two liver pathologists. The NAFLD activity score (NAS) and the pattern of liver injury (type 1 or adult versus type 2 or pediatric nonalcoholic steatohepatitis [NASH]) were recorded. Fibrosis was staged using a published 7‐point scale. The median age was 12 years (range, 4‐18 years); 63% were boys, and 52% were Caucasian. Fibrosis was present in 87% of patients; of these, stage 3 (bridging fibrosis) was present in 20%. No patient had cirrhosis. The median NAS was 4. Overlapping features of both type 1 (adult pattern) and type 2 (pediatric pattern) NASH were found in 82% of patients. Compared with patients with no or mild fibrosis, those with significant fibrosis were more likely to have higher lobular and portal inflammation scores (P < 0.01), perisinusoidal fibrosis (P < 0.001), and NAS ≥5 (P < 0.005). Serum aspartate aminotransferase levels were the only clinical or laboratory data that independently predicted severity of fibrosis (P = 0.003). Conclusion: Our results highlight the limitations of published proposals to classify pediatric NAFLD, and identified histological lesions associated with progressive disease. (HEPATOLOGY 2009.)

Genetic Modifiers of Liver Disease in Cystic Fibrosis

CONTEXT A subset (approximately 3%-5%) of patients with cystic fibrosis (CF) develops severe liver disease with portal hypertension. OBJECTIVE To assess whether any of 9 polymorphisms in 5 candidate genes (alpha(1)-antitrypsin or alpha(1)-antiprotease [SERPINA1], angiotensin-converting enzyme [ACE], glutathione S-transferase [GSTP1], mannose-binding lectin 2 [MBL2], and transforming growth factor beta1 [TGFB1]) are associated with severe liver disease in patients with CF. DESIGN, SETTING, AND PARTICIPANTS Two-stage case-control study enrolling patients with CF and severe liver disease with portal hypertension (CFLD) from 63 CF centers in the United States as well as 32 in Canada and 18 outside of North America, with the University of North Carolina at Chapel Hill as the coordinating site. In the initial study, 124 patients with CFLD (enrolled January 1999-December 2004) and 843 control patients without CFLD were studied by genotyping 9 polymorphisms in 5 genes previously studied as modifiers of liver disease in CF. In the second stage, the SERPINA1 Z allele and TGFB1 codon 10 genotype were tested in an additional 136 patients with CFLD (enrolled January 2005-February 2007) and 1088 with no CFLD. MAIN OUTCOME MEASURES Differences in distribution of genotypes in patients with CFLD vs patients without CFLD. RESULTS The initial study showed CFLD to be associated with the SERPINA1 Z allele (odds ratio [OR], 4.72; 95% confidence interval [CI], 2.31-9.61; P = 3.3 x 10(-6)) and with TGFB1 codon 10 CC genotype (OR, 1.53; 95% CI, 1.16-2.03; P = 2.8 x 10(-3)). In the replication study, CFLD was associated with the SERPINA1 Z allele (OR, 3.42; 95% CI, 1.54-7.59; P = 1.4 x 10(-3)) but not with TGFB1 codon 10. A combined analysis of the initial and replication studies by logistic regression showed CFLD to be associated with SERPINA1 Z allele (OR, 5.04; 95% CI, 2.88-8.83; P = 1.5 x 10(-8)). CONCLUSIONS The SERPINA1 Z allele is a risk factor for liver disease in CF. Patients who carry the Z allele are at greater risk (OR, approximately 5) of developing severe liver disease with portal hypertension.

Combined hereditary and somatic mutations of replication error repair genes result in rapid onset of ultra-hypermutated cancers

DNA replication−associated mutations are repaired by two components: polymerase proofreading and mismatch repair. The mutation consequences of disruption to both repair components in humans are not well studied. We sequenced cancer genomes from children with inherited biallelic mismatch repair deficiency (bMMRD). High-grade bMMRD brain tumors exhibited massive numbers of substitution mutations (>250/Mb), which was greater than all childhood and most cancers (>7,000 analyzed). All ultra-hypermutated bMMRD cancers acquired early somatic driver mutations in DNA polymerase ɛ or δ. The ensuing mutation signatures and numbers are unique and diagnostic of childhood germ-line bMMRD (P < 10−13). Sequential tumor biopsy analysis revealed that bMMRD/polymerase-mutant cancers rapidly amass an excess of simultaneous mutations (∼600 mutations/cell division), reaching but not exceeding ∼20,000 exonic mutations in <6 months. This implies a threshold compatible with cancer-cell survival. We suggest a new mechanism of cancer progression in which mutations develop in a rapid burst after ablation of replication repair.

Mutations in TJP2 cause progressive cholestatic liver disease

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.

Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension

Shneider BL, Bosch J, de Franchis R, Emre SH, Groszmann RJ, Ling SC, Lorenz JM, Squires RH, Superina RA, Thompson AE, Mazariegos GV. Portal Hypertension in Children: Expert Pediatric Opinion on the Report of the Baveno V Consensus Workshop on Methodology of Diagnosis and Therapy in Portal Hypertension.

NOTCH2 mutations in Alagille syndrome

Background Alagille syndrome (ALGS) is a dominant, multisystem disorder caused by mutations in the Jagged1 (JAG1) ligand in 94% of patients, and in the NOTCH2 receptor in <1%. There are only two NOTCH2 families reported to date. This study hypothesised that additional NOTCH2 mutations would be present in patients with clinical features of ALGS without a JAG1 mutation. Methods The study screened a cohort of JAG1-negative individuals with clinical features suggestive or diagnostic of ALGS for NOTCH2 mutations. Results Eight individuals with novel NOTCH2 mutations (six missense, one splicing, and one non-sense mutation) were identified. Three of these patients met classic criteria for ALGS and five patients only had a subset of features. The mutations were distributed across the extracellular (N=5) and intracellular domains (N=3) of the protein. Functional analysis of four missense, one nonsense, and one splicing mutation demonstrated decreased Notch signalling of these proteins. Subjects with NOTCH2 mutations demonstrated highly variable expressivity of the affected systems, as with JAG1 individuals. Liver involvement was universal in NOTCH2 probands and they had a similar prevalence of ophthalmologic and renal anomalies to JAG1 patients. There was a trend towards less cardiac involvement in the NOTCH2 group (60% vs 100% in JAG1). NOTCH2 (+) probands exhibited a significantly decreased penetrance of vertebral abnormalities (10%) and facial features (20%) when compared to the JAG1 (+) cohort. Conclusions This work confirms the importance of NOTCH2 as a second disease gene in ALGS and expands the repertoire of the NOTCH2 related disease phenotype.

Concurrent Versus Terminal Feedback: It May Be Better to Wait

Background Feedback is an important feature of simulation-based education. This study investigated the optimal timing of feedback for technical skills learning in novices. Method Thirty novice endoscopists were pretested on a colonoscopy simulator task. Participants then received feedback either during (concurrent) or after (terminal) each of their 12 practice trials. Effectiveness of training was assessed using an immediate posttest and one week later on retention and transfer tests. Measures included execution time and blinded expert assessments. Results Both groups performed similarly on the pre-, post-, and retention tests. At transfer, the terminal feedback group performed significantly better as measured by execution time, checklist, and global rating scores. The concurrent feedback group’s performance decreased significantly on the transfer test as compared with the posttest and retention test. Conclusions Not all feedback conditions seem equally effective. The use of terminal feedback resulted in better learning as demonstrated by superior performance during transfer.

Bone mineral assessment by dual energy X-ray absorptiometry in children with inflammatory bowel disease: evaluation by age or bone area.

Background Abnormal linear growth and deficient bone mineral acquisition may coexist in children with inflammatory bowel disease (IBD). Traditionally, bone mineral assessment by dual energy x-ray absorptiometry (DXA) involves comparison to age- and gender-matched reference ranges, and these studies in children with IBD show a high prevalence of osteopenia. Aims To compare the prevalence of osteopenia using two methods of interpretation; one adjusted for age and gender and the other adjusted for bone size and gender. Patients Forty-seven patients with Crohn disease (CD) and 26 patients with ulcerative colitis (UC) with a median age of 13.5 years (range, 5.5–18.2 years) were evaluated. Methods Lumbar spine (LS) and total body (TB) bone mineral content (BMC) were measured by DXA and converted to bone mineral density (BMD, g/cm2) corresponding to BMC divided by the bone area. Age and gender-matched BMD standard deviation scores (SDS) were based on reference data providing age- and gender-matched BMC and bone area. These data also allowed calculation of percentage of predicted bone area for age and gender (ppBone Area) and percentage of predicted BMC for Bone Area (ppBMC). Results Patients with CD were shorter than those with UC (median height, SDS, −0.9 v 0, P < 0.05). Median ppBone Area for LS and TB for the whole group was 85% (10th centile, 68; 90th centile 99) and 81% (10th centile 66; 90th centile, 97), respectively. The ppBone Area at both sites was directly related to height SDS and BMI SDS (r > 0.5; P < 0.005). Median BMD SDS for LS and TB was −1.6 (10th centile −3.6; 90th centile, −0.2) and −0.9 (10th centile, −2.4; 90th centile, 0.4), respectively. Median ppBMC for LS and TB was 98% (10th centile, 84%; 90th centile, 113%) and 101% (10th centile 94%; 90th centile, 107%), respectively. The ppBMC showed no relationship to ppBone Area (r = 0.1, NS). Failure to account for bone area led to a label of moderate or severe osteopenia in 65% of cases. After adjustment for bone area, the proportion of children with osteopenia fell to 22%. Conclusions The data suggest that children with IBD often have small bones for age because they have growth retardation. When DXA data are interpreted with adjustment for bone size, most children were found to have adequate bone mass. Correct interpretation of DXA is important for identifying children who may be at a real risk of osteoporosis.

Primary Prophylaxis of Variceal Hemorrhage in Children With Portal Hypertension: A Framework for Future Research

Nonselective β-blocker therapy and endoscopic variceal ligation reduce the incidence of variceal hemorrhage in cirrhotic adults, but their use in children is controversial. There are no evidence-based recommendations for the prophylactic management of children at risk of variceal hemorrhage due to the lack of appropriate randomized controlled trials. In a recent gathering of experts at the American Association for the Study of Liver Diseases annual meeting, significant challenges were identified in attempting to design and implement a clinical trial of primary prophylaxis in children using either of these therapies. These challenges render such a trial unfeasible, primarily due to the large sample size required, inadequate knowledge of appropriate dosing of β-blockers, and difficulty in recruiting to a trial of endoscopic variceal ligation. Pediatric research should focus on addressing questions of natural history and diagnosis of varices, prediction of variceal bleeding, optimal approaches to β-blocker and ligation therapy, and alternative study designs to explore therapeutic efficacy in children.

Prevalence of Hepatopulmonary Syndrome in Children

OBJECTIVE. The hepatopulmonary syndrome is defined as a triad of liver disease, hypoxemia, and intrapulmonary vascular dilation. The reported prevalence of hepatopulmonary syndrome in adults with cirrhosis ranges from 4% to 29%; however, the prevalence of hepatopulmonary syndrome and its outcome in children is unknown. The objective of this study was to describe prospectively the prevalence of intrapulmonary vascular dilation and hepatopulmonary syndrome in children with liver disease. METHODS. Pulse oximetry was undertaken in children with liver disease, and those with oxygen saturation ≤97%, those with cirrhosis, and those with clinically severe portal hypertension from other causes underwent contrast-enhanced echocardiography for detection of intrapulmonary vascular dilations. Patients with intrapulmonary vascular dilation underwent arterial blood gas analysis and technetium-99m–labeled macroaggregated albumin scan. RESULTS. Oxygen saturation was measured in 301 children and was ≤97% in 8. These 8 and an additional 18 patients with cirrhosis or portal hypertension underwent contrast-enhanced echocardiography. Seven (27%) patients had intrapulmonary vascular dilation detected by contrast-enhanced echocardiography; 2 of these patients had abnormal arterial blood gas analysis and thus met diagnostic criteria for hepatopulmonary syndrome (representing 8% of patients with cirrhosis or severe portal hypertension). Both patients with hepatopulmonary syndrome had abnormal pulse oximetry. Technetium-99m–labeled macroaggregated albumin scans for 6 patients showed a median 6.5% (range: 4%–12%) tracer uptake outside the lungs. CONCLUSIONS. Hepatopulmonary syndrome occurs in an important minority of children with cirrhosis or severe portal hypertension. Additional studies should be undertaken to determine the importance of intrapulmonary vascular dilation without hepatopulmonary syndrome and the impact of hepatopulmonary syndrome on the outcomes of affected children.