Radana Kotalova

Severe bile salt export pump deficiency : 82 different ABCB11 mutations in 109 families

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.

Variants of CARD15, TNFA and PTPN22 and susceptibility to Crohn’s disease in the Czech population: high frequency of the CARD15 1007fs

Crohns disease (CD) has been shown to be associated with the variants in the CARD15 gene as well as in other genes involved in the immune response. The frequencies of the variants profoundly differ among populations and so does the associated risk. We examined the associations of variants in the CARD15, TNFA and PTPN22 genes with pediatric-onset and adult-onset CD in the Czech population. Genotype, phenotype and allelic frequencies were compared between 345 patients with CD (136 pediatric-onset and 209 adult-onset patients) and 501 unrelated healthy controls. At least one minor allele of the CARD15 gene was carried by 46% patients and only 21% control subjects (OR = 3.2, 95% CI 2.4-4.4). In a multiple logistic regression model, the strongest association with CD was found for the 1007fs variant (OR = 4.6, 95% CI 3.0-7.0), followed by p.G908R (OR = 2.9, 95% CI 1.5-5.7) and p.R702W (OR = 1.7, 95% CI 1.0-2.9), while no independent association was found for the remaining variants in the CARD15 gene (p.268S, p.955I and p.289S), for the p.R620W variant in the PTPN22 gene or for the g.-308G>A variant in the TNFA gene. The age at CD onset was strongly modified by positivity for the 1007fs allele: it was present in 42% pediatric-onset and only 25% adult-onset patients. In conclusion, we report a high frequency of the minor allele of the CARD15 1007fs polymorphism in the Czech population and a strong effect of this allele on the age at disease onset.

Disease activity is an important factor for indeterminate interferon-γ release assay results in children with inflammatory bowel disease.

Background: Interferon-&ggr; release assay (IGRA) is widely used for screening of latent tuberculosis (TB) before and during biological therapy (BT). An indeterminate result of IGRA represents a limitation in the management of inflammatory bowel disease (IBD). Data on factors influencing IGRA results are scarce in children. The aim of the study was to identify factors influencing IGRA results in children with IBD. Methods: Seventy-two children with IBD (59 Crohn disease, 11 ulcerative colitis, 2 IBD-unclassified) indicated for BT were tested for TB infection (history, TB skin test, chest radiograph, IGRA; QuantiFERON—TB Gold in tube [QFT]) and consecutively retested using QFT in 1-year intervals. Results: We recorded 165 results of QFT (3% positive, 87% negative, and 10% indeterminate results). During follow-up we identified 4 conversions of negative QFT to positivity (3%) and 4 reversions (4%). Patients with indeterminate results of QFT had significantly lower actual weight-for-height z score (P = 0.022), higher platelet count (P = 0.00017), and lower levels of serum albumin (P = 0.015) compared with patients with positive or negative QFT. Indeterminate QFT was associated with corticosteroid treatment, BT, and disease activity, but not with treatment by immunomodulators. In a subanalysis of patients with Crohn disease alone, Pediatric Crohns Disease Activity Index was identified as single independent risk factor for indeterminate results (P = 0.00037). Conclusions: Although corticosteroid treatment is traditionally considered to be the main risk factor for indeterminate results of IGRA, the disease activity of IBD has even more profound effects on the results.

Hepatic phenotypes of HNF1B gene mutations: A case of neonatal cholestasis requiring portoenterostomy and literature review

Hepatocyte nuclear factor 1-β (HNF1B) defects cause renal cysts and diabetes syndrome (RCAD), or HNF1B-maturity-onset diabetes of the young. However, the hepatic phenotype of HNF1B variants is not well studied. We present a female neonate born small for her gestational age [birth weight 2360 g; -2.02 standard deviations (SD) and birth length 45 cm; -2.40 SD at the 38(th) gestational week]. She developed neonatal cholestasis due to biliary atresia and required surgical intervention (portoenterostomy) when 32-d old. Following the operation, icterus resolved, but laboratory signs of liver dysfunction persisted. She had hyperechogenic kidneys prenatally with bilateral renal cysts and pancreatic hypoplasia postnatally that led to the diagnosis of an HNF1B deletion. This represents the most severe hepatic phenotype of an HNF1B variant recognized thus far. A review of 12 published cases with hepatic phenotypes of HNF1B defects allowed us to distinguish three severity levels, ranging from neonatal cholestasis through adult-onset cholestasis to non-cholestatic liver impairment, all of these are associated with congenital renal cysts and mostly with diabetes later in life. We conclude that to detect HNF1B variants, neonates with cholestasis should be checked for the presence of renal cysts, with special focus on those who are born small for their gestational age. Additionally, patients with diabetes and renal cysts at any age who develop cholestasis and/or exocrine pancreatic insufficiency should be tested for HNF1B variants as the true etiological factor of all disease components. Further observations are needed to confirm the potential reversibility of cholestasis in infancy in HNF1B mutation/deletion carriers.

Association of IL23R p.381Gln and ATG16L1 p.197Ala with Crohn disease in the Czech population.

Objectives: An association of variants in the genes encoding the interleukin 23 receptor (IL23R, p.Arg381Gln, rs11209026), and the autophagy-related gene 16-like 1 (ATG16L1, p.Ala197Thr, rs2241880) with Crohn disease (CD) was identified by whole genome association studies, and subsequently confirmed by other works. The aim of this study was to assess this association in the Czech population. Subjects and Methods: In a case-control study 333 patients with CD (137 paediatric and 196 adult-onset) and 499 unrelated healthy controls were genotyped using TaqMan SNP assays. Results: The IL23R p.381Gln allele was protective against CD in the Czech population (allelic frequency 3.2% in patients vs 5.5% in control subjects; OR 0.56, 95% CI 0.33–0.93, P = 0.02). ATG16L1 p.197Ala allele conferred increased risk of CD (allelic frequency 60% in patients vs 51% in controls; OR 1.25, 95% CI 1.02–1.52, P = 0.03). There was no appreciable difference in the effect of the associated alleles across the strata of CARD15-conferred risk. The IL23R and ATG16L1 variants did not influence the age at diagnosis, and in the genotype-phenotype analysis, the only detected association was a weak one between IL23R p.381Gln and involvement of the upper gastrointestinal tract (uncorrected P = 0.031). Conclusions: We confirmed the role of IL23R and ATG16L1 in the CD susceptibility in the Czech population, and found a weak protective effect of IL23R p.381Gln against upper gastrointestinal tract involvement.

Alagille Syndrome Mimicking Biliary Atresia in Early Infancy.

Alagille syndrome may mimic biliary atresia in early infancy. Since mutations in JAG1 typical for Alagille syndrome type 1 have also been found in biliary atresia, we aimed to identify JAG1 mutations in newborns with proven biliary atresia (n = 72). Five biliary atresia patients with cholestasis, one additional characteristic feature of Alagille syndrome and ambiguous liver histology were single heterozygotes for nonsense or frameshift mutations in JAG1. No mutations were found in the remaining 67 patients. All “biliary atresia” carriers of JAG1 null mutations developed typical Alagille syndrome at the age of three years. Our data do not support association of biliary atresia with JAG1 mutations, at least in Czech patients. Rapid testing for JAG1 mutations could prevent misdiagnosis of Alagille syndrome in early infancy and improve their outcome.

Wilson disease as a cause of liver injury in cystic fibrosis

Cystic fibrosis-related liver disease affects approximately one third of all patients with cystic fibrosis. Initial signs of other liver diseases including the genetically determined disorders of the liver co-inherited with cystic fibrosis may be obscured by or ascribed to cystic fibrosis-related liver disease. We report a patient shown to suffer simultaneously from cystic fibrosis and hepatic Wilson disease. Our case documents that in patients with cystic fibrosis presenting with liver disease, when unusual clinical and/or laboratory abnormalities appear and fail to respond to standard therapy, a second disease, including rare inherited metabolic disorders such as the hepatic form of Wilson disease or alpha(1)-antitrypsin deficiency, should be suspected.

Choledochal Cyst with 17q12 Chromosomal Duplication

The 17q12 chromosomal region carries the HNF1B gene, mutations of which cause various conditions. When searching for HNF1B/17q12 rearrangements among children with biliary atresia and/or choledochal cysts, we identified a male proband carrying a 17q12 duplication spanning 1698 kb that included 24 genes from TBC1D3C to HNF1B. The boy presented with cholestatic jaundice at the age of 2 weeks due to a choledochal cyst sized 15 ×12 mm (type Ia according to the Todani classification). He underwent a shunt surgery consisting of a hepaticojejunostomy using Roux‐en‐Y loop at the age of 2 months, which led to a permanent relief of cholestasis. Perioperative liver histology revealed significant hepatic fibrosis and bile ductular proliferation. At 17 years, he has a mildly enlarged liver with decreased elasticity, an upper‐normal–sized spleen, normal biochemistry values, and no renal or hepatic cysts. We report the first hepatobiliary phenotype in a patient with an HNF1B overdosage.