Browsing by Author "Bull, Laura N."

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    Identification of PKD1L1 Gene Variants in Children with the Biliary Atresia Splenic Malformation Syndrome
    (Wiley, 2019) Berauer, John-Paul; Mezina, Anya I.; Okou, David T.; Sabo, Aniko; Muzny, Donna M.; Gibbs, Richard A.; Hegde, Madhuri R.; Chopra, Pankaj; Cutler, David J.; Perlmutter, David H.; Bull, Laura N.; Thompson, Richard J.; Loomes, Kathleen M.; Spinner, Nancy B.; Rajagopalan, Ramakrishnan; Guthery, Stephen L.; Moore, Barry; Yandell, Mark; Harpavat, Sanjiv; Magee, John C.; Kamath, Binita M.; Molleston, Jean P.; Bezerra, Jorge A.; Murray, Karen F.; Alonso, Estella M.; Rosenthal, Philip; Squires, Robert H.; Wang, Kasper S.; Finegold, Milton J.; Russo, Pierre; Sherker, Averell H.; Sokol, Ronald J.; Karpen, Saul J.; Pediatrics, School of Medicine
    Biliary atresia (BA) is the most common cause of end‐stage liver disease in children and the primary indication for pediatric liver transplantation, yet underlying etiologies remain unknown. Approximately 10% of infants affected by BA exhibit various laterality defects (heterotaxy) including splenic abnormalities and complex cardiac malformations — a distinctive subgroup commonly referred to as the biliary atresia splenic malformation (BASM) syndrome. We hypothesized that genetic factors linking laterality features with the etiopathogenesis of BA in BASM patients could be identified through whole exome sequencing (WES) of an affected cohort. DNA specimens from 67 BASM subjects, including 58 patient‐parent trios, from the NIDDK‐supported Childhood Liver Disease Research Network (ChiLDReN) underwent WES. Candidate gene variants derived from a pre‐specified set of 2,016 genes associated with ciliary dysgenesis and/or dysfunction or cholestasis were prioritized according to pathogenicity, population frequency, and mode of inheritance. Five BASM subjects harbored rare and potentially deleterious bi‐allelic variants in polycystin 1‐like 1, PKD1L1, a gene associated with ciliary calcium signaling and embryonic laterality determination in fish, mice and humans. Heterozygous PKD1L1 variants were found in 3 additional subjects. Immunohistochemical analysis of liver from the one BASM subject available revealed decreased PKD1L1 expression in bile duct epithelium when compared to normal livers and livers affected by other non‐cholestatic diseases. Conclusion WES identified bi‐allelic and heterozygous PKD1L1 variants of interest in 8 BASM subjects from the ChiLDReN dataset. The dual roles for PKD1L1 in laterality determination and ciliary function suggest that PKD1L1 is a new, biologically plausible, cholangiocyte‐expressed candidate gene for the BASM syndrome.
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    Identification of Polycystic Kidney Disease 1 Like 1 Gene Variants in Children With Biliary Atresia Splenic Malformation Syndrome
    (Wiley, 2019-01-21) Berauer, John-Paul; Mezina, Anya I.; Okou, David T.; Sabo, Aniko; Muzny, Donna M.; Gibbs, Richard A.; Hegde, Madhuri R.; Chopra, Pankaj; Cutler, David J.; Perlmutter, David H.; Bull, Laura N.; Thompson, Richard J.; Loomes, Kathleen M.; Spinner, Nancy B.; Rajagopalan, Ramakrishnan; Guthery, Stephen L.; Moore, Barry; Yandell, Mark; Harpavat, Sanjiv; Magee, John C.; Kamath, Binita M.; Molleston, Jean P.; Bezerra, Jorge A.; Murray, Karen F.; Alonso, Estella M.; Rosenthal, Philip; Squires, Robert H.; Wang, Kasper S.; Finegold, Milton J.; Russo, Pierre; Sherker, Averell H.; Sokol, Ronald J.; Karpen, Saul J.; Pediatrics, School of Medicine
    Biliary atresia (BA) is the most common cause of end-stage liver disease in children and the primary indication for pediatric liver transplantation, yet underlying etiologies remain unknown. Approximately 10% of infants affected by BA exhibit various laterality defects (heterotaxy) including splenic abnormalities and complex cardiac malformations — a distinctive subgroup commonly referred to as the biliary atresia splenic malformation (BASM) syndrome. We hypothesized that genetic factors linking laterality features with the etiopathogenesis of BA in BASM patients could be identified through whole exome sequencing (WES) of an affected cohort. DNA specimens from 67 BASM subjects, including 58 patient-parent trios, from the NIDDK-supported Childhood Liver Disease Research Network (ChiLDReN) underwent WES. Candidate gene variants derived from a pre-specified set of 2,016 genes associated with ciliary dysgenesis and/or dysfunction or cholestasis were prioritized according to pathogenicity, population frequency, and mode of inheritance. Five BASM subjects harbored rare and potentially deleterious bi-allelic variants in polycystin 1-like 1, PKD1L1, a gene associated with ciliary calcium signaling and embryonic laterality determination in fish, mice and humans. Heterozygous PKD1L1 variants were found in 3 additional subjects. Immunohistochemical analysis of liver from the one BASM subject available revealed decreased PKD1L1 expression in bile duct epithelium when compared to normal livers and livers affected by other non-cholestatic diseases. Conclusion: WES identified bi-allelic and heterozygous PKD1L1 variants of interest in 8 BASM subjects from the ChiLDReN dataset. The dual roles for PKD1L1 in laterality determination and ciliary function suggest that PKD1L1 is a new, biologically plausible, cholangiocyte-expressed candidate gene for the BASM syndrome.
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    Mutation Analysis and Disease Features at Presentation in a Multi-Center Cohort of Children With Monogenic Cholestasis
    (Wiley, 2021) Hertel, Paula M.; Bull, Laura N.; Thompson, Richard J.; Goodrich, Nathan P.; Ye, Wen; Magee, John C.; Squires, Robert H.; Bass, Lee M.; Heubi, James E.; Kim, Grace E.; Ranganathan, Sarangarajan; Schwarz, Kathleen B.; Bozic, Molly A.; Horslen, Simon P.; Clifton, Matthew S.; Turmelle, Yumirle P.; Suchy, Frederick J.; Superina, Riccardo A.; Wang, Kasper S.; Loomes, Kathleen M.; Kamath, Binita M.; Sokol, Ronald J.; Shneider, Benjamin L.; Childhood Liver Disease Research Network (ChiLDReN); Pediatrics, School of Medicine
    Objectives: To advance our understanding of monogenic forms of intrahepatic cholestasis. Methods: Analyses included participants with pathogenic biallelic mutations in adenosine triphosphate (ATP)-binding cassette subfamily B member 11 (ABCB11) (bile salt export pump; BSEP) or adenosine triphosphatase (ATPase) phospholipid transporting 8B1 (ATP8B1) (familial intrahepatic cholestasis; FIC1), or those with monoallelic or biallelic mutations in adenosine triphosphate (ATP)-binding cassette subfamily B member 4 (ABCB4) (multidrug resistance; MDR3), prospectively enrolled in the Longitudinal Study of Genetic Causes of Intrahepatic Cholestasis (LOGIC; NCT00571272) between November 2007 and December 2013. Summary statistics were calculated to describe baseline demographics, history, anthropometrics, laboratory values, and mutation data. Results: Ninety-eight participants with FIC1 (n = 26), BSEP (n = 53, including 8 with biallelic truncating mutations [severe] and 10 with p.E297G or p.D482G [mild]), or MDR3 (n = 19, including four monoallelic) deficiency were analyzed. Thirty-five had a surgical interruption of the enterohepatic circulation (sEHC), including 10 who underwent liver transplant (LT) after sEHC. Onset of symptoms occurred by age 2 years in most with FIC1 and BSEP deficiency, but was later and more variable for MDR3. Pruritus was nearly universal in FIC1 and BSEP deficiency. In participants with native liver, failure to thrive was common in FIC1 deficiency, high ALT was common in BSEP deficiency, and thrombocytopenia was common in MDR3 deficiency. sEHC was successful after more than 1 year in 7 of 19 participants with FIC1 and BSEP deficiency. History of LT was most common in BSEP deficiency. Of 102 mutations identified, 43 were not previously reported. Conclusions: In this cohort, BSEP deficiency appears to be correlated with a more severe disease course. Genotype-phenotype correlations in these diseases are not straightforward and will require the study of larger cohorts.
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    Presentation and Outcomes of Infants With Idiopathic Cholestasis: A Multicenter Prospective Study
    (Wolters Kluwer, 2021-10-01) Hertel, Paula M.; Hawthorne, Kieran; Kim, Sehee; Finegold, Milton J.; Shneider, Benjamin L.; Squires, James E.; Gupta, Nitika A.; Bull, Laura N.; Murray, Karen F.; Kerkar, Nanda; Ng, Vicky L.; Molleston, Jean P.; Bezerra, Jorge A.; Loomes, Kathleen M.; Taylor, Sarah A.; Schwarz, Kathleen B.; Turmelle, Yumirle P.; Rosenthal, Philip; Magee, John C.; Sokol, Ronald J.; Pediatrics, School of Medicine
    Objectives: The aim of the study was to determine the frequency and natural history of infantile idiopathic cholestasis (IC) in a large, prospective, multicenter cohort of infants. Methods: We studied 94 cholestatic infants enrolled up to 6 months of age in the NIDDK ChiLDReN (Childhood Liver Disease Research Network) "PROBE" protocol with a final diagnosis of IC; they were followed up to 30 months of age. Results: Male sex (66/94; 70%), preterm birth (22/90 with data; 24% born at < 37 weeks' gestational age), and low birth weight (25/89; 28% born at <2500 g) were frequent, with no significant differences between outcomes. Clinical outcomes included death (n = 1), liver transplant (n = 1), biochemical resolution (total bilirubin [TB] ≤1 mg/dL and ALT < 35 U/L; n = 51), partial resolution (TB > 1 mg/dL and/or ALT > 35 U/L; n = 7), and exited healthy (resolved disease per study site report but without documented biochemical resolution; n = 34). Biochemical resolution occurred at median of 9 months of age. GGT was <100 U/L at baseline in 34 of 83 participants (41%). Conclusions: Frequency of IC and of death or liver transplant was less common in this cohort than in previously published cohorts, likely because of recent discovery and diagnosis of genetic etiologies of severe/persistent cholestasis that previously were labeled as idiopathic. Preterm birth and other factors associated with increased vulnerability in neonates are relatively frequent and may contribute to IC. Overall outcome in IC is excellent. Low/normal GGT was common, possibly indicating a role for variants in genes associated with low-GGT cholestasis-this warrants further study.