Concurrence of novel mutations causing Gilbert's and Dubin-Johnson syndrome with poor clinical outcomes in a Han Chinese family.

Dual-hereditary jaundice (Dubin-Johnson syndrome (DJS) and Gilbert's syndrome (GS)) is a rare clinical entity resulting from defects of the ATP binding cassette subfamily C member 2 (ABCC2) and UDP glucuronosyltransferase family 1 member A1 (UGT1A1) genes with autosomal recessive inheritance. In this study, we aimed to investigate the mutation profiles and characterize the phenotypes in a Han Chinese family with DJS and GS. Genetic screening for variants in the ABCC2 and UGT1A1, immunohistochemistry for expression of ABCC2, and histopathological examination were carried out. The proband and his brother had unconjugated and conjugated hyperbilirubinemia after birth. The proband's sister had only conjugated hyperbilirubinemia after birth. The proband developed into pleural effusions and ascites, pericardial thickening, intrahepatic and extrahepatic biliary duct dilatation, and enlarged gallbladder at age 50. Hepatocellular carcinoma occurred in the proband's brother at age 46. Seven compound defects of the ABCC2 gene [c.2414delG, p.(Ile1489Gly), p.(Thr1490Pro), and p.(Ile1491Gln)] and the UGT1A1 gene (c.-3279T>G, p.(Gly71Arg), and p.(Pro451Leu)) were identified in family members. Accumulation of pigment in hepatocytes characteristic of that in DJS was present in the proband and his brother. Expression of ABCC2 protein was markedly diminished in the patient's liver. Our results show a different genetic profile of DJS and GS in a Han Chinese family, indicating a more complex pattern of dual-hereditary jaundice among different populations. The present study illuminates the underpinnings of DJS and GS and extends the mutation profiles and phenotypes of these two syndromes in dual-hereditary jaundice.

Neonatal Dubin-Johnson syndrome: biochemical parameters, characteristics, and genetic variants study.

BACKGROUND: The clinical characteristics and gene mutation characteristics of children with Dubin-Johnson syndrome (DJS) need in-depth study. METHODS: The clinical and genomic data of neonatal Dubin-Johnson syndrome (NDJS) and 155 cases with idiopathic cholestasis (IC) were analyzed from June 2016 to August 2020 RESULTS: ABCC2 gene variants were identified in eight patients, including one patient with homozygous variants and seven patients with compound heterozygous variants. A total of 13 different ABCC variants were detected in the NDJS patients, including three nonsense variants, six missense variants, three frameshift variants, and a splice site variant. The variant c.2443C > T (p.R815X), c.4237_4238insCT (p.H1414Lfs*17), c.960_961insGT (p.L322Cfs*3), c.4250delC (p.S1417Ffs*14), c.2224G > A (p.D742N), c.4020G > C (p.K1340N), and c.2439 + 5G > A were not reported in the Human Gene Variant Database. There was no significance in the sex, birth weight, and onset age between the NDJS and IC groups. Compared with the IC group, the NDJS group had significantly higher levels of total bilirubin (TB), but a significantly lower level of alanine transaminase and a ratio of direct bilirubin (DB) to TB. There is no significance in total bile acid, gamma-glutamyl-transpeptidase, albumin, or international normalized ratio between the two groups. CONCLUSIONS: NDJS should be considered in prolonged neonatal intrahepatic cholestasis, especially in infants with normal or slightly elevated transaminase levels. IMPACT: Explore the biochemical parameters, characteristics, and genetic profile of NDJS. By summarizing the characteristics of biochemical indicators, seven new mutation types of the ABCC2 gene were detected, which expanded the mutation spectrum of the ABCC2 gene. NDJS should be considered in prolonged neonatal intrahepatic cholestasis, especially in infants with normal or slightly elevated transaminase levels.

Genotype-Phenotype Association in ABCC2 Exon 18 Missense Mutation Leading to Dubin-Johnson Syndrome: A Case Report.

We report a case of a patient with Dubin-Johnson syndrome confirmed by a genetic study. A 50-year-old woman who had symptoms of intermittent right upper quadrant abdominal pain was diagnosed with calculous cholecystitis at another institute and was presented to our hospital for a cholecystectomy. She had no history of liver disease, and her physical examination was normal. Abdominal computed tomography showed a gallbladder stone with chronic cholecystitis. During a laparoscopic cholecystectomy for cholecystitis, a smooth, black-colored liver was noted, and a liver biopsy was performed. The biopsy specimen showed coarse, dark brown granules in centrilobular hepatocytes via hematoxylin and eosin staining. We performed a genetic study using the blood samples of the patient. In the adenosine triphosphate-binding cassette subfamily C member 2 (ABCC2) mutation study, a missense mutation in exon 18 was noted. Based on the black-colored liver without nodularity, conjugated hyperbilirubinemia, the liver biopsy results of the coarse pigment in centrilobular hepatocytes, and the ABCC2 mutation, Dubin-Johnson syndrome was diagnosed. The patient was managed with conservative care using hepatotonics. One month after follow-up, total bilirubin and direct bilirubin remained in a similar range. Another follow-up was planned a month later, and the patient maintained her use of hepatotonics.

[The phenotypes and genotypes of four patients with Dubin-Johnson syndrome].

OBJECTIVE: To explore the genetic etiology in four patients with hyperbilirubinemia, and discuss the correlation between clinical characteristics and molecular basis. METHODS: The data of clinical manifestation and auxiliary examinations were collected. Genomic DNA of the four patients was extracted and analyzed by next-generation sequencing using the panel including genes involved in hereditary metabolic liver diseases. Suspected variants were verified by Sanger sequencing. RESULTS: All of the four patients were males with normal liver enzymes. It was revealed that all the patients had heterozygous variants, among which c.3011C>T, c.2443C>T and c.2556del were the variants which have not been reported previously. CONCLUSION: All of the patients were diagnosed as Dubin-Johnson syndrome (DJS) caused by ABCC2 gene variants. The novel variants add to the spectrum of genetic variants of the disease. Because of the favorite prognosis, precise diagnosis can greatly reduce the psychological pressure of patients and avoid excessive treatments. At the same time, it could provide pertinent genetic counseling for the families.

[Genetic analysis of a case with Dubin-Johnson syndrome due to two novel variants of ABCC2 gene].

OBJECTIVE: To explore the genetic etiology and differential diagnosis for a patient with jaundice. METHODS: Clinical data of the patient and his parents were collected. Genes associated with metabolic liver diseases were subjected to high-throughput sequencing. The pathogenicity of the candidate variants was predicted by using bioinformatics software. RESULTS: High-throughput sequencing revealed that the proband has harbored two variants of the ABCC2 gene (NM_000392) including c.3011C>T (p.T1004I) and c.3541C>T (p.R1181X), which were respectively inherited from his father and mother. Both variants have been previously unreported and predicted to be pathogenic by bioinformatics analysis. CONCLUSION: The proband was diagnosed with Dubin-Johnson syndrome due to the compound heterozygous variants of the ABCC2 gene. Genetic testing has enabled accurate differential diagnosis of Dubin-Johnson syndrome in this patient.

Dubin-Johnson Syndrome as Differential Diagnosis for Neonatal Cholestasis.

OBJECTIVES: Dubin-Johnson syndrome (DJS) is an autosomal recessive disorder in which multidrug-resistance-associated protein 2 (MRP2) deficiency causes an excretion disorder of conjugated bilirubin from hepatocytes into bile canaliculi. Its clinical presentation as neonatal cholestasis (NC) is rare but represents an important differential diagnosis. We aimed to define DJS-specific characteristics in NC, in particular in contrast to biliary atresia (BA) patients, and to highlight diagnostic tools that can help to avoid invasive diagnostic tests. METHODS: We performed a review of case records from 2006 to 2020 and compared 4 DJS patients to 26 patients with proven BA consecutively diagnosed from 2014 to 2017. DJS was diagnosed by urine coproporphyrin analysis (UCA) and by genetic analysis (GA) for disease-associated ABCC2 variants. RESULTS: Four male patients with NC were diagnosed with DJS by UCA and GA. DJS patients presenting as NC showed significantly lower values for aspartate aminotransferase (AST) (P < 0.001), for alanine aminotransferase (ALT) (P = 0.002) and for gamma-glutamyl transferase (GGT) (P < 0.001) compared with BA patients. Other examinations, however, could not clearly discriminate them (e.g.: stool colour, serum bile acids, total serum bilirubin). CONCLUSIONS: DJS is not only a rare differential diagnosis in NC with a suspicious phenotype (almost normal AST, ALT) but also shows overlapping features with BA. It should, therefore, be considered in every infant with NC and an atypical liver enzyme pattern to protect patients from unnecessary, invasive examinations. For this, UCA is a fast and reliable diagnostic tool. Confirmation based on GA is recommended. DJS patients have a good long-term prognosis.

A Case of Dubin-Johnson Syndrome Presenting as Neonatal Cholestasis With Paucity of Interlobular Bile Ducts.

Dubin-Johnson syndrome (DJS) is a rare autosomal recessive disorder that typically manifests in young adulthood as jaundice with conjugated hyperbilirubinemia. We report a case presenting as neonatal cholestasis with the unexpected histologic finding of paucity of interlobular bile ducts, a feature that is not typically seen in DJS. The diagnosis was confirmed by absent canalicular multidrug-resistance-associated protein 2 (MRP2) immunohistochemical staining on liver biopsy tissue and molecular genetic testing that demonstrated heterozygous mutations in the ATP-Binding Cassette Subfamily C Member 2 (ABCC2) gene, including a novel missense mutation. This report describes a case of DJS with atypical clinicopathologic findings and suggests that DJS should be considered in patients with neonatal cholestasis and bile duct paucity.

[Clinical and pathological features of Dubin-Johnson syndrome].

Objective: To explore the clinical and pathological features of Dubin-Johnson syndrome. Methods: The clinical and pathological characteristics of 18 cases of Dubin-Johnson syndrome diagnosed in the Department of Pathology of the Third Affiliated Hospital of Sun Yat-sen University from 2008 to 2018 were analyzed. Related literature was reviewed. Results: There were 15 male and three female patients. The male-to-female ratio was 5∶1. The age of the patients ranged from 17 to 73 years (median 24 years). Common clinical manifestations were jaundice, anorexia, and abnormal liver function tests. The pathological feature was the deposition of dark brown particles in the hepatocytes, especially those around the central veins. Conclusions: Dubin-Johnson syndrome mainly occurs in young people. The characteristic pathological changes are the deposition of dark brown particles in the hepatocytes around the central veins of the liver. The diagnosis of Dubin-Johnson syndrome mainly relies on clinical manifestations, laboratory examinations, histopathological examinations and genetic testing. The understanding of Dubin-Johnson syndrome can help reduce the rates of missed diagnosis and misdiagnosis of the disease.

Genetic contribution of ABCC2 to Dubin-Johnson syndrome and inherited cholestatic disorders.

BACKGROUND AND AIMS: The ABCC2 gene is implicated in Dubin-Johnson syndrome (DJS), a rare autosomal recessive liver disorder. The primary aim of this study was to determine the diagnostic value of ABCC2 genetic testing in the largest cohort of DJS reported to date. The high number of patients with cholestatic manifestations in this series prompted us to evaluate the genetic contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders. METHODS: The cohort study included 32 patients with clinical DJS diagnosis, and 372 patients referred for the following disorders: low phospholipid-associated cholelithiasis (LPAC) syndrome, intrahepatic cholestasis of pregnancy (ICP) and benign recurrent intrahepatic cholestasis (BRIC). ABCC2 was screened by next-generation sequencing. RESULTS: Most patients with clinical DJS had positive genetic diagnosis (n = 30; 94%), with a great diversity of point mutations and copy number variations in ABCC2. Strikingly, eight (27%) of these patients showed transient cholestatic features at presentation: four neonatal cholestasis, two ICP, one contraceptive-induced cholestasis and one sporadic cholestasis. Conversely, the frequency of rare, heterozygous, potentially pathogenic ABCC2 variants in patients with LPAC, ICP or BRIC did not differ significantly from that of the general population. CONCLUSIONS: This large series reveals that DJS is a highly homogeneous Mendelian disorder involving a large spectrum of ABCC2 variants. Genetic testing is crucial to establish early DJS diagnosis in patients with atypical presentations, such as neonatal cholestasis. This study also provides no evidence for the contribution of rare, potentially pathogenic ABCC2 variants to other inherited cholestatic disorders.

Mutation spectrum and biochemical features in infants with neonatal Dubin-Johnson syndrome.

BACKGROUND: Dubin-Johnson syndrome (DJS) is an autosomal recessive disorder presenting as isolated direct hyperbilirubinemia.DJS is rarely diagnosed in the neonatal period. The purpose of this study was to clarify the clinical features of neonatal DJS and to analyze the genetic mutation of adenosine triphosphate-binding cassette subfamily C member 2 (ABCC2). METHODS: From 2013 to 2018, 135 infants with neonatal cholestasis at Seoul National University Hospital were enrolled. Genetic analysis was performed by neonatal cholestasis gene panel. To clarify the characteristics of neonatal DJS, the clinical and laboratory results of 6 DJS infants and 129 infants with neonatal cholestasis from other causes were compared. RESULTS: A total of 8 different ABCC2 variants were identified among the 12 alleles of DJS. The most common variant was p.Arg768Trp (33.4%), followed by p.Arg100Ter (16.8%). Three novel variants were identified (p.Gly693Glu, p.Thr394Arg, and p.Asn718Ser). Aspartate transaminase (AST) and alanine transaminase (ALT) levels were significantly lower in infants with DJS than in infants with neonatal cholestasis from other causes. Direct bilirubin and total bilirubin were significantly higher in the infants with DJS. CONCLUSIONS: We found three novel variants in 6 Korean infants with DJS. When AST and ALT levels are normal in infants with neonatal cholestasis, genetic analysis of ABCC2 permits an accurate diagnosis.

[Clinical features and ABCC2 genotypic analysis of an infant with Dubin-Johnson syndrome].

Dubin-Johnson syndrome (DJS) is an autosomal recessive disorder resulting from biallelic mutations of ABCC2 gene, with long-term or intermittent conjugated hyperbilirubinemia being the main clinical manifestation. This paper aims to report the clinical features and ABCC2 genotypes of an infant with DJS. A 9.5-month-old male infant was referred to the hospital due to abnormal liver function discovered over 9 months. The major clinical presentation was prolonged jaundice since neonatal period. A series of biochemistry analysis revealed markedly elevated total bilirubin, conjugated bilirubin and total bile acids. The patient had been managed in different hospitals, but the therapeutic effects were unsatisfactory due to undetermined etiology. Physical examination revealed jaundiced skin and sclera, and a palpable liver 3 cm below the right subcostal margin with medium texture. The spleen was not enlarged. Genetic analysis revealed a splice-site variant c.3988-2A>T and a nonsense variant c.3825C>G (p.Y1275X) in the ABCC2 gene of the infant, which were inherited from his mother and father respectively. The former had not been previously reported. Then ursodeoxycholic acid and phenobarbital were given orally. Half a month later, as a result, his jaundice disappeared and the biochemistry indices improved. However, the long-term outcome needs to be observed. Literature review revealed that neonates/infants with DJS presented with cholestatic jaundice soon after birth as the major clinical feature, and the ABCC2 variants exhibited marked heterogeneity.

Clinical, Pathologic, and Genetic Features of Neonatal Dubin-Johnson Syndrome: A Multicenter Study in Japan.

OBJECTIVE: To clarify the clinical, pathologic, and genetic features of neonatal Dubin-Johnson syndrome. STUDY DESIGN: Ten patients with neonatal Dubin-Johnson syndrome were recruited from 6 pediatric centers in Japan between September 2013 and October 2016. Clinical and laboratory course, macroscopic and microscopic liver findings, and molecular genetic findings concerning ATP-binding cassette subfamily C member 2 (ABCC2) were retrospectively and prospectively examined. RESULTS: All neonates exhibited cholestasis, evident as prolonged jaundice with or without acholic stools and elevations of serum direct bilirubin as well as γ-glutamyltransferase or total bile acids. Only 38% (3 of 8) of patients who underwent liver biopsy showed a grossly black liver or melanin-like pigment deposits in hepatocytes; their biopsies were performed in early infancy. Immunohistochemically, all liver specimens showed no expression of multidrug resistance-associated protein 2 but increased expression of the bile salt export pump protein. Homozygous or compound heterozygous pathogenic variants of ABCC2 were identified in all patients, representing 11 distinct pathogenic variants including 2 not previously reported. CONCLUSIONS: Immunohistochemical staining of the liver for multidrug resistance-associated protein 2 and molecular genetic analysis of ABCC2 are crucial for accurate diagnosis of neonatal Dubin-Johnson syndrome.

Conjugated hyperbilirubinemia after surgery. A diagnosis of Dubin-Johnson syndrome confirmed by genetic testing.

Dubin-Johnson syndrome is a rare benign inherited disorder, caused by mutations in ABCC2 gen, and it is characterized by predominantly conjugated hyperbilirubinemia that can be increased by intercurrent infectious illnesses or surgical procedures. We report the case of a 10 year-old patient who showed, after a surgical procedure for peritonitis due to appendicitis, jaundice and predominantly conjugated hyperbilirubinemia, and he was diagnosed with Dubin-Johnson syndrome by genetic testing.

Molecular Genetic Dissection and Neonatal/Infantile Intrahepatic Cholestasis Using Targeted Next-Generation Sequencing.

OBJECTIVES: To ascertain a molecular genetic diagnosis for subjects with neonatal/infantile intrahepatic cholestasis (NIIC) by the use of next-generation sequencing (NGS) and to perform a genotype-phenotype correlation. STUDY DESIGN: We recruited Japanese subjects with NIIC who had no definitive molecular genetic diagnosis. We developed a diagnostic custom panel of 18 genes, and the amplicon library was sequenced via NGS. We then compared clinical data between the molecular genetically confirmed subjects with NIIC. RESULTS: We analyzed 109 patients with NIIC ("genetic cholestasis," 31 subjects; "unknown with complications" such as prematurity, 46 subjects; "unknown without complications," 32 subjects), and a molecular genetic diagnosis was made for 28 subjects (26%). The rate of positive molecular genetic diagnosis in each category was 22 of 31 (71%) for the "genetic cholestasis" group, 2 of 46 (4.3%) for the "unknown with complications" group, and 4 of 32 (12.5%) for the "unknown without complications" group. The grouping of the molecular diagnoses in the group with genetic cholestasis was as follows: 12 with Alagille syndrome, 5 with neonatal Dubin-Johnson syndrome, 5 with neonatal intrahepatic cholestasis caused by citrin deficiency, and 6 with progressive familial intrahepatic cholestasis or benign recurrent intrahepatic cholestasis with low gamma-glutamyl transpeptidase levels. Several clinical datasets, including age of onset, direct bilirubin, and aminotransferases, were significantly different between the disorders confirmed using molecular genetic diagnosis. CONCLUSION: Targeted NGS can be used for molecular genetic diagnosis in subjects with NIIC. Clinical diagnosis should be accordingly redefined in the view of molecular genetic findings.

Inherited disorders of bilirubin clearance.

Inherited disorders of hyperbilirubinemia may be caused by increased bilirubin production or decreased bilirubin clearance. Reduced hepatic bilirubin clearance can be due to defective (i) unconjugated bilirubin uptake and intrahepatic storage, (ii) conjugation of glucuronic acid to bilirubin (e.g., Gilbert syndrome, Crigler-Najjar syndrome, Lucey-Driscoll syndrome, breast milk jaundice), (iii) bilirubin excretion into bile (Dubin-Johnson syndrome), or (iv) conjugated bilirubin re-uptake (Rotor syndrome). In this review, the molecular mechanisms and clinical manifestations of these conditions are described, as well as current approaches to diagnosis and therapy.

Inherited disorders of bilirubin transport and conjugation: new insights into molecular mechanisms and consequences.

Inherited disorders of bilirubin metabolism might reduce bilirubin uptake by hepatocytes, bilirubin conjugation, or secretion of bilirubin into bile. Reductions in uptake could increase levels of unconjugated or conjugated bilirubin (Rotor syndrome). Defects in bilirubin conjugation could increase levels of unconjugated bilirubin; the effects can be benign and frequent (Gilbert syndrome) or rare but severe, increasing the risk of bilirubin encephalopathy (Crigler-Najjar syndrome). Impairment of bilirubin secretion leads to accumulation of conjugated bilirubin (Dubin-Johnson syndrome). We review the genetic causes and pathophysiology of disorders of bilirubin transport and conjugation as well as clinical and therapeutic aspects. We also discuss the possible mechanisms by which hyperbilirubinemia protects against cardiovascular disease and the metabolic syndrome and the effects of specific genetic variants on drug metabolism and cancer development.

Neonatal Dubin-Johnson syndrome: novel compound heterozygous mutation in the ABCC2 gene.

Dubin-Johnson syndrome (DJS) is an autosomal recessive inherited disorder characterized by conjugated hyperbilirubinemia. Neonatal-onset DJS is rare. It is caused by dysfunction of adenosine triphosphate-binding cassette, sub-family C, member 2 (ABCC2). We found a novel compound heterozygous mutation of DJS-related gene: W709R (T2145C): a missense mutation in exon 17, and R768W (C2302T), a missense mutation in exon 18. Serum diglucuronosyl bilirubin/monoglucuronosyl bilirubin ratio was high. ABCC2 may excrete diglucuronosyl bilirubin preferentially over monoglucuronosyl bilirubin.

Clinical characteristics and follow-up of a newborn with Dubin-Johnson Syndrome: A clinical case report.

BACKGROUND: Dubin-Johnson syndrome (DJS) is a rare autosomal recessive liver disorder, characterized by conjugated hyperbilirubinemia. This case report investigates the clinical characteristics and longitudinal outcomes of a neonate diagnosed with DJS. METHODS: A newborn presented with elevated bilirubin levels and abnormal liver enzyme readings. Comprehensive genetic evaluation was conducted, which included peripheral blood sample collection from the infant and both parents after obtaining informed consent and high-throughput trio exome sequencing was performed. The genetic analysis revealed 2 significant mutations in the ABCC2 gene on chromosome 10: the insertion mutation c.4237(exon30)_c.4238(exon30)ins CT, inherited from the father, and the missense mutation c.517(exon5)G > A, inherited from the mother. Both mutations were classified as pathogenic according to the ACMG 2015 guidelines, indicating a compound heterozygous inheritance pattern. The patient's treatment regimen included phototherapy, which was initiated to address her jaundice upon admission. To support liver function and regulate gut activity, oral ursodeoxycholic acid (20 mg/kg/dose, twice a day) and probiotics were administered. Additionally, a postdischarge medication plan involving a low-dose regimen of phenobarbital (3.5 mg/kg/dose, twice a day) was implemented for 2 weeks. RESULTS: During a 2-year follow-up after discharge, the infant's bilirubin levels significantly decreased, and liver enzymes, including GGT, progressively normalized. CONCLUSION: This case report enhances the understanding of DJS in neonates by emphasizing the clinical ramifications of compound heterozygous mutations within the ABCC2 gene and documenting the evolution of the disease. The gradual normalization of liver function tests suggests potential compensatory mechanisms in response to the genetic abnormalities in neonates with DJS. The correlation between the patient's genetic profile of compound heterozygosity and her milder clinical phenotype warrants attention, suggesting that this specific genetic configuration may be associated with less severe manifestations of the disease. The necessity for long-term follow-up is highlighted, recognizing that intercurrent stress conditions could influence the hepatic profile and potentially exacerbate symptoms. Such sustained observation is crucial to further delineate the genomic and clinical landscape of DJS, offering opportunities to refine prognostic and therapeutic approaches.