Patricia McClean

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.

Mutations in VPS33B, encoding a regulator of SNARE-dependent membrane fusion, cause arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome

ARC syndrome (OMIM 208085) is an autosomal recessive multisystem disorder characterized by neurogenic arthrogryposis multiplex congenita, renal tubular dysfunction and neonatal cholestasis with bile duct hypoplasia and low gamma glutamyl transpeptidase (gGT) activity. Platelet dysfunction is common. Affected infants do not thrive and usually die in the first year of life. To elucidate the molecular basis of ARC, we mapped the disease to a 7-cM interval on 15q26.1 and then identified germline mutations in the gene VPS33B in 14 kindreds with ARC. VPS33B encodes a homolog of the class C yeast vacuolar protein sorting gene, Vps33, that contains a Sec1-like domain important in the regulation of vesicle-to-target SNARE complex formation and subsequent membrane fusion.

Seamless management of biliary atresia in England and Wales (1999–2002)

BACKGROUND Before 1999, infants born in the UK with suspected biliary atresia were investigated in regional centres, and, if confirmed, a Kasai operation was done there. Since 1999, all infants with suspected biliary atresia in England and Wales, UK, have been referred to one of three designated centres where both the Kasai operation and liver transplantation (if necessary) could be done. METHODS We assessed clearance of jaundice (bilirubin <20 micromol/L) as an early outcome in all cases of biliary atresia referred from one of the three centres. We then estimated survival using the Kaplan-Meier method with endpoints of liver transplantation or death. FINDINGS 148 infants with biliary atresia were treated between January, 1999, and June, 2002. A primary portoenterostomy was done in 142 (96%) infants and a primary liver transplant in five (3%). One child died before any intervention. Early clearance of jaundice after portoenterostomy was achieved in 81 of 142 (57%) infants. Liver transplantation was done in 52 (37%) of those undergoing portoenterostomy. 13 (9%) infants died. Of the 135 children who survived, 84 (62%) still have their native liver and 51 (38%) had transplantation. The median follow-up of survivors was 2.13 (range 0.5-4.1) years. The overall 4-year estimated actuarial survival was 89% (95% CI 82-94). The 4-year estimated actuarial survival with native liver was 51% (42-59%). INTERPRETATION Our early results suggest that surgical outcome can be improved by centralisation of care to supra-regional centres.

Biliary atresia in England and Wales: results of centralization and new benchmark

INTRODUCTION Biliary atresia (BA) is a rare, potentially life-threatening condition of the newborn presenting with conjugated jaundice. Typically, it is treated by an initial attempt to restore bile flow (the Kasai portoenterostomy [KP]) as soon as possible after diagnosis and, if this fails, liver transplantation. Since 1999, the treatment of BA has been centralized to 3 centers in England and Wales able to offer both treatment options. The aim of this study was to review the outcome of this policy change and provide a national benchmark. METHODS The management of all infants born within England and Wales during the period January 1999 to December 2009 was assessed using 3 key performance indicators such as median time to KP, percentage clearance of jaundice (≤20 mol/L) post-KP, and 5- and 10-year native liver and true survival estimates. Data are quoted as median (range), and P < .05 was considered significant. RESULTS A total of 443 infants had confirmed BA; and of these, most were isolated BA (n = 359), with 84 having other significant anomalies (but predominantly BA splenic malformation syndrome). Four infants died before any biliary intervention. Kasai portoenterostomy was performed in 424 infants (median age, 54 [range 7-209] days), and a primary liver transplant was performed in 15. Clearance of jaundice post-KP was achieved in 232 (55%). There were 41 deaths, including 4 (10%) without any intervention, 24 (58%) post-KP usually because of end-stage liver disease and mostly on a transplant waiting list, and 13 (32%) post-LT usually because of multiorgan failure. Overall, the 5- and 10-year native liver survival estimates were 46% (95% confidence interval [CI], 41-51) and 40% (95% CI, 34-46), respectively. The 5- and 10-year true patient survival estimates were 90% (95% CI, 88-93) and 89% (95% CI, 86-93), respectively. Outcome was worse for those with other anomalies (lower clearance of jaundice post-KP [43% vs 57%; odds ratio, 1.7; 95% CI, 1.04-2.8]; P = .02) and an increased mortality overall (eg, at 5 years, 72 [95% CI, 64-83] vs 94 [95% CI, 91-96]; χ(2) = 33; P < .0001). CONCLUSIONS National outcome measures in BA appear better than those from previously published series from comparable countries and may be attributed to centralization of surgical and medical resources.

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.

Randomized, double‐blind, placebo‐controlled trial of corticosteroids after Kasai portoenterostomy for biliary atresia

The objective of this study was to evaluate adjuvant corticosteroids after Kasai portoenterostomy for biliary atresia. The study consisted of a prospective, 2‐center, double‐blind, randomized, placebo‐controlled trial of post–Kasai portoenterostomy corticosteroids (oral prednisolone: 2 mg/kg/day from day 7 to day 21 and 1 mg/kg/day from day 22 to day 28). The data were compared with χ 2 or Mann‐Whitney tests, as appropriate. Seventy‐one postoperative infants with type 3 biliary atresia were randomized to receive either oral prednisolone (n = 36) or a placebo (n = 37). At 1 month, the median bilirubin level was lower in the steroid group (66 versus 92 μmol/L, P = 0.06), but no difference was evident at 6 (P = 0.56) or 12 (P = 0.3) months. The proportion of infants with a normal bilirubin level (<20 μmol/L) at 6 (47% versus 49%, P = 0.89) and 12 months (50% versus 40%, P = 0.35) was not significantly different. The need for transplantation by 6 (12% versus 13%, P = 0.99) and 12 months (26% versus 35%, P = 0.47) was not significantly different. The steroid effect was more pronounced in younger infants (less than 70 days at Kasai portoenterostomy, n = 51), with a reduced bilirubin level at 1 month (64 versus 117 μmol/L, P = 0.01) and with a greater proportion with a normal bilirubin level at 12 months (54% versus 37%, P = 0.22). Conclusion: There was a beneficial effect on the rate of reduction of bilirubin in the early postoperative period (specifically in infants less than 70 days old at surgery), but this steroid regimen did not reduce the need for liver transplantation. (HEPATOLOGY 2007;46:1821–1827.)

Endoscopic rectal sparing in children with untreated ulcerative colitis.

Background Ulcerative colitis (UC) typically is associated with a confluent proctitis, whereas rectal sparing may be seen in large bowel Crohn disease (CD). A few studies have reported rectal sparing in UC and suggested that this might indicate a more severe form of the disease. This study aimed to determine the prevalence and prognostic significance of rectal sparing in children with newly diagnosed, untreated UC. Methods The records of all children with untreated UC presenting to a regional pediatric gastroenterology service between January 1996 and December 2001 were retrospectively reviewed. Patients were divided into two groups according to the endoscopic appearance of the rectum: Group 1 (proctitis) and Group 2 (rectal sparing). Clinical features, intractability index (duration of active disease as a proportion of length of follow-up), response to treatment, relapse index (number of recurrences per year), and the need for surgery were compared. Results Thirty children with untreated UC were identified. Seven (23%) had rectal sparing at initial endoscopy, but disease distribution was otherwise similar in both groups. Presenting symptoms were similar in those with and without rectal sparing. In Group 1, 20 (87%) children achieved remission with initial medical treatment, compared with 3 (43%) in Group 2 (P < 0.05). The intractability index was higher in children with rectal sparing, but the difference was not statistically significant (P = 0.22). During a median follow-up period of 2 years, one (4%) child in Group 1 and two (29%) children in Group 2 experienced primary sclerosing cholangitis, and two (29%) children with rectal sparing required colectomy, compared with none in Group 1. Conclusions Endoscopic rectal sparing was seen in 23% of children with newly diagnosed, untreated UC, but this feature did not correlate with presenting symptoms. However, the presence of rectal sparing may indicate more aggressive disease that is less responsive to medical treatment.

Neonatal liver failure

Liver failure in the neonatal period is challenging to diagnose and manage, and still carries a high mortality. With ongoing developments in the field of metabolic disorders and antiviral therapy, and the ability to offer liver transplantation to small babies, an overall survival of 40% has been achieved. Early recognition of liver failure, good supportive care and prompt referral to a paediatric liver transplant centre are essential elements in improving the outcome for these babies. Decisions about contra-indications to and timing of transplantation are complex as many of the disease processes are still evolving in the neonatal period, and extrahepatic disease, which cannot be corrected by a transplant, may appear later.

Renal function evaluated by measured GFR during follow‐up in pediatric liver transplant recipients

Abstract:  Calcineurin inhibitors form the mainstay of immunosuppression in pediatric liver transplantation, but may cause significant nephrotoxicity. We evaluated renal function in liver transplant recipients treated with a tacrolimus‐based immunosuppressive regimen. GFR was measured using 99 mTc‐DTPA in patients pretransplant and annually thereafter. GFR calculated by Schwartz formula was compared with the measured values. Sixty patients who underwent 69 transplants were followed for at least one yr post‐transplant (median three yr). In children over two yr of age at transplant GFR fell significantly from pretransplant (140 mL/min/1.73 m2) to one yr post‐transplant (112 mL/min/1.73 m2) (p = 0.01) but thereafter there was no significant decline. In younger children the picture was confounded by maturation of renal function, but again there was no significant fall to five yr post‐transplant. Although 13 (22%) patients developed renal dysfunction post‐transplant, none required renal replacement therapy. cGFR correlated poorly with measured values (r = 0.21). Use of a tacrolimus‐based immunosuppressive regimen is associated with an initial decline in GFR, though this picture is confounded in younger children by normal maturation of renal function. There is no further significant fall in GFR in the medium‐term. The Schwartz formula is inaccurate in determining GFR in this patient group.

The reduced left lateral segment in pediatric liver transplantation: An alternative to the monosegment graft

Abstract:  Tailoring graft size to small paediatric recipients is a challenge. We have developed a reduced left lateral segment as an alternative to monosegment transplantation for small size recipients. Since November 2000, 89 children have been transplanted with 100 deceased donor liver grafts in our unit. Our median patient and graft survival is 89% and 88% respectively. Four of these cases were performed using a new technique of creating a small donor graft by reducing the left lateral segment. The median weight of the reduced liver graft was 264 g (range: 165–390 g). The median blood transfusion requirement was 101 mL/kg body weight (range 69–167 mL/kg). The median values of peak ALT were 1473 IU/L, INR 2.2 and bilirubin 293 μmol/L in the first two wk following surgery. One neonatal recipient died five days after transplantation from a massive intracranial haemorrhage despite satisfactory graft function. Another recipient with excellent graft function died 10 months later from primary pulmonary hypertension and secondary cardiac failure. Hepatic artery thrombosis occurred in one patient with successful revascularization but he was retransplanted three months later for chronic rejection. No biliary or venous outflow complications occurred in this group. This technique of reduced left lateral segment liver transplantation is an alternative to the monosegment graft and allows small recipients to be successfully transplanted with few technical complications related to graft preparation.