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Browsing by Author "Harpavat, Sanjiv"
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Item 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 MedicineBiliary 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.Item 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 MedicineBiliary 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.Item Serum bile acids as a prognostic biomarker in biliary atresia following Kasai portoenterostomy(Wolters Kluwer, 2023) Harpavat, Sanjiv; Hawthorne, Kieran; Setchell, Kenneth D. R.; Narvaez Rivas, Monica; Henn, Lisa; Beil, Charlotte A.; Karpen, Saul J.; Ng, Vicky L.; Alonso, Estella M.; Bezerra, Jorge A.; Guthery, Stephen L.; Horslen, Simon; Loomes, Kathy M.; McKiernan, Patrick; Magee, John C.; Merion, Robert M.; Molleston, Jean P.; Rosenthal, Philip; Thompson, Richard J.; Wang, Kasper S.; Sokol, Ronald J.; Shneider, Benjamin L.; Childhood Liver Disease Research Network (ChiLDReN); Pediatrics, School of MedicineBackground and aims: In biliary atresia, serum bilirubin is commonly used to predict outcomes after Kasai portoenterostomy (KP). Infants with persistently high levels invariably need liver transplant, but those achieving normalized levels have a less certain disease course. We hypothesized that serum bile acid levels could help predict outcomes in the latter group. Approach and results: Participants with biliary atresia from the Childhood Liver Disease Research Network were included if they had normalized bilirubin levels 6 months after KP and stored serum samples from the 6-month post-KP clinic visit ( n = 137). Bile acids were measured from the stored serum samples and used to divide participants into ≤40 μmol/L ( n = 43) or >40 μmol/L ( n = 94) groups. At 2 years of age, the ≤40 μmol/L compared with >40 μmol/L group had significantly lower total bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, bile acids, and spleen size, as well as significantly higher albumin and platelet counts. Furthermore, during 734 person-years of follow-up, those in the ≤40 μmol/L group were significantly less likely to develop splenomegaly, ascites, gastrointestinal bleeding, or clinically evident portal hypertension. The ≤40 μmol/L group had a 10-year cumulative incidence of liver transplant/death of 8.5% (95% CI: 1.1%-26.1%), compared with 42.9% (95% CI: 28.6%-56.4%) for the >40 μmol/L group ( p = 0.001). Conclusions: Serum bile acid levels may be a useful prognostic biomarker for infants achieving normalized bilirubin levels after KP.