Novel ABCB11 mutations in a Thai infant with progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis （PFIC） type 2 is caused by mutations in ABCB11, which encodes bile salt export pump （BSEP）. We report a Thai female infant who presented with progressive cholestatic jaundice since 1 mo of age, with normal serum y-glutamyltransferase. Immunohistochemical staining of the liver did not demonstrate BSEP along the canaliculi, while multidrug resistance protein 3 was expressed adequately. Novel mutations in ABCB11, a four-nucleotide deletion in exon 3, c.90_93delGAAA, and a single-nucleotide insertion in exon 5, c.249_250insT, were identified, with confirmation in her parents. These mutations were predicted to lead to synthesis of truncated forms of BSEP. Immunostaining and mutation analysis thus established the diagnosis of PFIC type     

进行性家族性肝内胆汁淤积

进行性家族性肝内胆汁淤积(PFIC)是一组常染色体隐性遗传肝细胞源性儿童胆汁淤积症。根据病因可以分为3型：1型源于ATP8B1基因的突变,2型源于ABCB11基因的突变,3型源于MDR3基因的突变。临床以有胆汁淤积以及严重的皮肤瘙痒为特征。治疗方法包括药物治疗、外科部分胆道外分流术和肝移植三种方法。     

Expanding etiology of progressive familial intrahepatic cholestasis

BACKGROUND Progressive familial intrahepatic cholestasis(PFIC) refers to a disparate group of autosomal recessive disorders that are linked by the inability to appropriately form and excrete bile from hepatocytes, resulting in a hepatocellular form of cholestasis. While the diagnosis of such disorders had historically been based on pattern recognition of unremitting cholestasis without other identified molecular or anatomic cause, recent scientific advancements have uncovered multiple specific responsible proteins. The variety of identified defects has resulted in an ever-broadening phenotypic spectrum, ranging from traditional benign recurrent jaundice to progressive cholestasis and end-stage liver disease.AIM To review current data on defects in bile acid homeostasis, explore the expanding knowledge base of genetic based diseases in this field, and report disease characteristics and management.METHODS We conducted a systemic review according to PRISMA guidelines. We performed a Medline/PubMed search in February-March 2019 for relevant articles relating to the understanding, diagnosis, and management of bile acid homeostasis with a focus on the family of diseases collectively known as PFIC. English only articles were accessed in full. The manual search included references of retrieved articles.We extracted data on disease characteristics, associations with other diseases, and treatment. Data was summarized and presented in text, figure, and table format.RESULTS Genetic-based liver disease resulting in the inability to properly form and secrete bile constitute an important cause of morbidity and mortality in children and increasingly in adults. A growing number of PFIC have been described based on an expanded understanding of biliary transport mechanism defects and the development of a common phenotype.CONCLUSION We present a summary of current advances made in a number of areas relevant to both the classically described FIC1(ATP8 B1), BSEP(ABCB11), and MDR3(ABCB4) transporter deficiencies, as well as more recently described gene mutations--TJP2(TJP2), FXR(NR1 H4), MYO5 B(MYO5 B), and others which expand the etiology and understanding of PFIC-related cholestatic diseases and bile transport.     

Single-center experience in management of progressive familial intrahepatic cholestasis

Background and study aimsProgressive familial intrahepatic cholestasis (PFIC) is an autosomal recessively inherited disease that causes intrahepatic-hepatocellular cholestasis. PFIC constitutes approximately 10–15% of cholestatic liver diseases in children. The aim of this study is to draw attention to this group of diseases, which pose a higher risk, in societies where consanguineous marriage is more common, and to share our experiences since the studies in the literature, regarding this group of diseases are case series with small number of patients.Patients and methodsThis cross-sectional study was conducted on 34 patients who were admitted with jaundice and diagnosed by genetic analysis, between January 2015 and July 2020.ResultsWe found 17.6% of patients with PFIC type 1, 55.9% patients had PFIC type 2, 14.7% patients had PFIC type 3, 8.8% patients had PFIC type 4 and 2.9% patients had PFIC type 5. Partial internal biliary diversion was performed in 5 (14.7%) patients, who had severe itching during follow-up, did not respond to medical treatment, and did not have significant fibrosis in liver biopsy yet. The degree of itching before PIBD was rated as +4 (cutaneous erosion, bleeding and scarring), in 5 patients and the rates were 0 (absent) in two patients, and +1 (mild itching) in 3 patients, 6 months after PIBD, these differences were statistically significant(p = 0.027). The mean weight z score was-1.43 (-3.72-+0.73), before PIBD, while it was 0.39(-1.86 -+2.45), six months after PIBD; the diference was statistically significant(p = 0.043). Liver transplantation was performed in 12 (35.3%) patients with significant fibrosis in liver biopsy and developing signs of portal hypertension.ConclusionThe PFIC disease group is a heterogeneous disease group that is difficult to diagnose and treat. It should be considered in patients with cholestasis and/or pruritus and those with a history of consanguineous marriage between parents and death of a sibling with similar clinical symptoms.     

进行性家族性肝内胆汁淤积症3型:2例报道并文献复习

进行性家族性肝内胆汁淤积症是一组罕见的常染色体隐性遗传病,起病早,进展快,死亡率高,治疗较为困难。本文报道进行性家族性肝内胆汁淤积症3型2例,并附文献复习。     

Novel ATP8B1 mutation in an adult male with progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis type 1 is a rare disease that is characterized by low serum γ-glutamyltransferase levels due to mutation in ATP8B1. We present a 23-year-old male who experienced persistent marked pruritus for eighteen years and recurrent jaundice for thirteen years, in addition to cholestasis that eventually became fatal. Genetic sequencing studies of the entire coding (exon) sequences of ATP8B1 and ABCB11 uncovered a novel heterozygous missense 3035G>T mutation (S1012I) and a synonymous 696T>C mutation in ATP8B1. The patient’s progression was associated with not only impaired familial intrahepatic cholestasis 1 (FIC1) function but also impaired bile salt export pump expression due to the impaired FIC1 function. Our findings show that patients with intermittent cholestasis can develop progressive liver disease even after several decades and require regular follow up.     

Prenatal diagnosis of progressive familial intrahepatic cholestasis type 2

Background and Aim:  Progressive familial intrahepatic cholestasis type 2 (PFIC2) results from genetic defects of the hepatobiliary bile salt export pump (BSEP, ABCB11 ) at chromosome 2q24. Patients with progressive cholestasis and liver cirrhosis usually need liver transplantation in the first decade. Mutations in ABCB11 are also associated with benign recurrent intrahepatic cholestasis type 2 and intrahepatic cholestasis of pregnancy in adult patients. We aimed to make the prenatal diagnosis of PFIC2.
Methods:  Genetic diagnosis was performed by genomic DNA analysis. Prenatal genetic diagnosis was made by fetal amniotic DNA and chorionic DNA analysis.
Results:  We report on two families of PFIC2 with inherited compound heterozygous mutations of ABCB11 (M183V and R303K in Family 1, V284L and 1145delC in Family 2) from the parents. An infant with heterozygous M183V mutation was later born healthy in Family 1. A fetus with compound heterozygous missense mutation V284L and 1145delC was terminated in Family 2.
Conclusion:  Prenatal diagnosis of PFIC2 was helpful to prevent further affected children in families with this fatal disease.     

Newer variants of progressive familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of disorders characterized by defects in bile secretion and presentation with intrahepatic cholestasis in infancy or childhood. The most common types include PFIC 1 (deficiency of FIC1 protein, ATP8B1 gene mutation), PFIC 2 (bile salt export pump deficiency, ABCB11 gene mutation), and PFIC 3 (multidrug resistance protein-3 deficiency, ABCB4 gene mutation). Mutational analysis of subjects with normal gamma-glutamyl transferase cholestasis of unknown etiology has led to the identification of newer variants of PFIC, known as PFIC 4, 5, and MYO5B related (sometimes known as PFIC 6). PFIC 4 is caused by the loss of function of tight junction protein 2 (TJP2) and PFIC 5 is due to NR1H4 mutation causing Farnesoid X receptor deficiency. MYO5B gene mutation causes microvillous inclusion disease (MVID) and is also associated with isolated cholestasis. Children with TJP2 related cholestasis (PFIC-4) have a variable spectrum of presentation. Some have a self-limiting disease, while others have progressive liver disease with an increased risk of hepatocellular carcinoma. Hence, frequent surveillance for hepatocellular carcinoma is recommended from infancy. PFIC-5 patients usually have rapidly progressive liver disease with early onset coagulopathy, high alpha-fetoprotein and ultimately require a liver transplant. Subjects with MYO5 B-related disease can present with isolated cholestasis or cholestasis with intractable diarrhea (MVID). These children are at risk of worsening cholestasis post intestinal transplant (IT) for MVID, hence combined intestinal and liver transplant or IT with biliary diversion is preferred. Immunohistochemistry can differentiate most of the variants of PFIC but confirmation requires genetic analysis.     

Ductopenia and cirrhosis in a 32-year-old woman with progressive familial intrahepatic cholestasis type 3: A case report and review of the literature

Progressive familial intrahepatic cholestasis type 3 is caused by a mutation in the ATP-binding cassette, subfamily B, member 4 (ABCB4) gene encoding multidrug resistance protein 3. A 32-year-old woman with a history of acute hepatitis at age 9 years was found to have jaundice during pregnancy in 2008, and was diagnosed as having intrahepatic cholestasis of pregnancy. In 2009, she underwent cholecystectomy for gallstones and chronic cholecystitis. However, itching and jaundice did not resolve postoperatively. She was admitted to our hospital with fatigue, jaundice, and a recently elevated γ-glutamyl transpeptidase level. Liver biopsy led to the diagnosis of biliary cirrhosis with ductopenia. Genetic testing revealed a pathogenic heterozygous mutation, ex13 c.1531G A (p.A511 T), in the ABCB4 gene. Her father did not carry the mutation, but her mother's brother carried the heterozygous mutation. We made a definitivediagnosis of familial intrahepatic cholestasis type 3. He symptoms and liver function improved after 3 mo o treatment with ursodeoxycholic acid.     

Clinical and ABCB11 profiles in Korean infants with progressive familial intrahepatic cholestasis

AIM: To investigate clinical profiles and mutations of ABCB11 in Koreans with progressive familial intrahepatic cholestasis 2 and review the differences between Koreans and others.METHODS: Of 47 patients with neonatal cholestasis, five infants had chronic intrahepatic cholestasis with normal γ-glutamyl transpeptidase. Direct sequencing analyses of ABCB11, including exons and introns, were performed from peripheral blood.RESULTS: Living donor-liver transplantation was performed in four patients because of rapidly progressive hepatic failure and hepatocellular carcinoma. Three missense mutations were found in two patients: compound heterozygous 677CT(S226L)/3007GA(G1003R) and heterozygous 2296GA(G766R). The mutations were located near and in the transmembranous space. CONCLUSION: Alterations in the transmembrane of the bile salt export pump in the Korean infants were different from those previously reported in Chinese, Japanease, Taiwanese, and European patients.     

New tight junction protein 2 variant causing progressive familial intrahepatic cholestasis type 4 in adults: A case report

BACKGROUND Progressive familial intrahepatic cholestasis(PFIC)encompasses a group of autosomal recessive disorders with high morbidity and mortality.Variants in the gene encoding tight junction protein-2(TJP2)have been linked to PFIC type 4(PFIC4),which predominantly presents in childhood.However,there are only limited data from adults with TJP2-related PFIC4.We report a family with an autosomal recessive disorder with a novel variant in the TJP2 gene in adults with very variable expression of PFIC4.CASE SUMMARY The index patient presented at 19 years old with liver cirrhosis and variceal bleeding and was treated with endoscopic banding and beta-blockers.In 2018,he developed primary liver cancer that was treated with radiofrequency ablation followed by liver transplantation in 2019.Genetic testing revealed a novel homozygous TJP2 variant causing PFIC4(TJP2([NM_004817.3]:c.[3334C>T];[3334C>T])).The consanguineous family consists of the father and mother(both heterozygous)and their 12 children,of which five carry the variant in a homozygous state;however,these five siblings have highly variable expression of PFIC4.Two homozygous brothers had cirrhosis and portal hypertension at diagnosis at the ages of 19 and 36.Two other homozygous brothers,age 23 and 19,and the homozygous sister,age 21,have elevated liver enzymes but presently no cirrhosis,which may suggest an age-dependent penetrance.In addition,five sisters had severe and mild intrahepatic cholestasis of pregnancy and carry the TJP2 variant in a homozygous and heterozygous state,respectively.CONCLUSION This novel TJP2 variant is associated with PFIC4 causing severe liver disease with cirrhosis and primary liver cancer in adolescents/adults.     

进行性家族性肝内胆汁淤积症3型

进行性家族性肝内胆汁淤积症3型(progressive familial intrahepatic cholestasis type 3,PFIC3)是一种常染色体隐性遗传性疾病,由编码多药耐药蛋白3(multidrug resistance protein 3,MDR3)的AB CB4(ATP-bindingcassette,sub-family B,member 4)基因突变引起~([1]).PFIC3临床上可表现为反复瘙痒、黄疸、白陶土样便、肝脾肿大及胃肠道出血等,常在成年前进展为肝硬化和肝衰竭~([1-3]).PFIC3是进行性家族性肝内胆汁淤积症的一种亚型,与进行性家族性肝内胆汁淤积症1型和2型的主要区别在于血清γ-谷氨酰转肽酶(GGT)升高及肝组织病理表现为明显的小胆管增生~([4]).     

ABCB11 gene mutations in Chinese children with progressive intrahepatic cholestasis and low γ glutamyltransferase

Background: Progressive familial intrahepatic cholestasis type 2 (PFIC2) is a severe autosomal recessive liver disorder of childhood that can cause cholestasis and progress to end‐stage liver disease. ABCB11 gene mutations causing PFIC2 have been reported in some population groups, but not in mainland Chinese. Aims: To elucidate the existence of and characterize ABCB11 gene mutations in mainland Chinese with progressive intrahepatic cholestasis and low γ glutamyltransferase (GGT). Methods: Twenty‐four children presenting with progressive intrahepatic cholestasis and low GGT were admitted to a tertiary paediatric hospital in eastern China from January 2004 to July 2007. All encoding exons and flanking areas of the ABCB11 gene were sequenced. Hepatic histopathology results were obtained by review of the medical record. Results: Twelve novel mutations of ABCB11 gene were found in seven patients: three nonsense mutations, six missense mutations, two splicing mutations and one intronic mutation. Giant cell transformation of hepatocytes was demonstrated in all the four patients with ABCB11 mutations and four of 12 patients without mutations in coding sequences of ABCB11 gene who received liver needle biopsy. Conclusions: ABCB11 gene mutations play an important role in Chinese patients with progressive intrahepatic cholestasis and low GGT. The characteristics of ABCB11 gene mutations in Chinese are different from other population groups. Histological examination may be helpful in diagnosis of PFIC2.     

黄疸型婴儿肝炎预后与血清谷氨酰转肽酶水平变化的关系

目的研究血清谷氨酰转肽酶（GGT）水平与黄疸型婴儿肝炎预后的关系。方法回顾性分析38例除外先天性胆道闭锁和其他先天性异常后的黄疸型婴儿肝炎的临床资料,以死亡、肝移植或等待肝移植、1岁后仍持续或反复黄疸为预后不良指标,按最初GGT的高低分为≤50U／L和〉50U／L组并分析两组患者的预后有无差别。结果最初的GGT≤50U／L组6例中5例预后不良;〉50U／L组32例中3例预后不良,差别有统计学意义（P=0．001）。动态分析发现,8例预后不良患儿中5例GGT始终在正常水平,与胆红素和转氨酶等指标波动无关;3例GGT在开始时升高,随病情进展,反而降为正常。预后良好患儿,随黄疸消退,GGT渐达高峰然后恢复正常。结论在黄疸型婴儿肝炎中,GGT不升或随黄疸加深或持续,GGT反而降为正常,是预后不良的指标;病程中黄疸波动,而GGT始终正常者,需考虑有进行性家族性肝内胆汁淤积可能。     

A new ABCB11 mutation in two Italian children with familial intrahepatic cholestasis

Progressive familial intrahepatic cholestasis (PFIC) syndromes are characterized by defects in transporters of conjugated bile acids into the bile canaliculus. Three genes (ATP8B1, ABCB11, ABCB4) are associated with the different forms, but no easy genotype–phenotype correlations help in the prioritization for gene testing. We developed a denaturing high-performance liquid chromatography (DHPLC) method to screen patients with PFIC for mutations in ATP8B1 and ABCB11, and combined genetic analyses with immunolabeling in liver for the ABCB11 and ABCB4 gene products. Used in combination with commercially available antibodies on liver specimens, the DHPLC approach allowed us to confirm the clinical diagnosis in two Italian sisters and to identify a novel missesnse mutation in ABCB11. Our findings are expected to facilitate detection of the molecular cause of PFIC in affected families.     

Normal pancreatic secretion in children with progressive familial intrahepatic cholestasis type 1

Objective. Progressive familial intrahepatic cholestasis type 1 (PFIC1) is a rare, autosomal, recessive, inherited disease resulting from mutations in the ATP8B1 gene which is expressed at high levels in the small intestine and pancreas and at lower levels in the liver. Given this expression pattern, patients might be expected to have a pancreatic phenotype. Although pancreatitis and steatorrhea have been reported in patients with PFIC1, the available data on pancreatic function are not fully convincing. Therefore, the objective of this study was to assess exocrine pancreatic function in patients with PFIC1. Material and methods. Three subjects with a diagnosis of PFIC1 were included in the study. The diagnosis was confirmed by molecular analysis of ATP8B1. Prior to surgical treatment (biliary diversion), two patients had steatorrhea and in the third patient, a borderline value for fecal fat excretion was documented. In one patient, liver transplantation also was subsequently performed. Exocrine pancreatic secretion was assessed by the use of fecal elastase-1 and chymotrypsin tests. Fecal lipase concentrations were determined in order to exclude isolated lipase deficiency. Other typical diagnostic procedures were performed annually. Results. The results of the fecal tests were within the normal range. None of the three patients experienced any episodes that could be related to acute or chronic pancreatitis. Laboratory tests including serum amylase and lipase tests were always normal. Abdominal ultrasonography findings did not show any pancreatic pathology. Conclusions. Pancreatic secretion in the study patients with progressive familial intrahepatic cholestasis type 1 was normal. The observed steatorrhea was not related to pancreatic insufficiency.     

进行性家族性肝内胆汁淤积症3型合并AIH-PBC重叠综合征1例

背景自身免疫性肝炎(autoimmune hepatitis,AIH)和原发性胆汁性胆管炎(primary biliary cholangitis,PBC)的AIH-PBC重叠综合征在肝病中并非少见,同时合并进行性家族性肝内胆汁淤积症则较为罕见,通常容易造成漏诊.病例简介本例患者因为肝功能异常伴黄疸11年均未能明确诊断.在本院住院期间,AIH-PBC重叠综合征获得确诊.在接受正规治疗后,效果欠佳.给与遗传性肝病基因检测,发现ABCB4基因突变,提示患者同时合并进行性家族性肝内胆汁淤积症3型(progressive familial intrahepatic cholestasis type 3,PFIC3).2020年和2021年,患者先后因为“上消化道出血”又2次入住我院,病情呈现不断加重的趋势.结论对于1例久未获得确诊的肝病患者,通过生化学、血清学、影像学、组织学等检查,明确了AIH-PBC重叠综合征的诊断.但本病例由于脾脏明显肿大,似不能完全以AIH-PBC重叠综合征加以解释,因此对患者进行了遗传性肝病相关的基因检测,发现了ABCB4基因突变,避免了PFIC3的漏诊.     

进行性家族性肝内胆汁淤积症研究进展

进行性家族性肝内胆汁淤积症(progressive familial intrahepatic cholestasis, PFIC)是一组常染色体隐性遗传病,以肝内胆汁淤积为主要表现,通常在婴儿或儿童期起病。根据致病基因不同,PFIC 可分为 6 型。这些患儿若得不到及时干预,多在儿童期发展为肝硬化和肝衰竭。因此早期诊断及干预十分重要。本文将对 PFIC 的发病机制、临床表现、诊断及治疗的研究进展作综述。     

Combined features of low phospholipid‐associated cholelithiasis and progressive familial intrahepatic cholestasis 3

Adenosine triphosphate‐binding cassette, subfamily B, member 4 (ABCB4) gene alterations can cause two distinct clinical entities: progressive familial intrahepatic cholestasis type 3 (PFIC3) and low phospholipid‐associated cholelithiasis (LPAC). Based on the findings in two siblings and a review of the literature, we aimed to identify determinants of disease phenotypic traits associated with ABCB4 gene alterations. Two siblings presented, before the age of 30 years, recurrent symptomatic cholelithiasis and extensive biliary fibrosis that progressed towards portal hypertension and liver failure necessitating liver transplantation. We analysed the sequence of the ABCB4 gene and immunolocalization of the protein in the liver. Sequence analysis of ABCB11, potentially involved in similar symptoms, was also performed. Two heterozygous non‐synonymous variants of ABCB4 were found in both siblings. One of them (c.959C>T; p.Ser320Phe) was previously implicated in LPAC and the second one (c.2858C>A; p.Ala953Asp) in PFIC3. Both patients were also heterozygous for the ABCB11 variant Val444Ala, which predisposes to cholestatic disorders. ABCB4 was normally detected at the canalicular membrane of hepatocytes. The review of ABCB4 gene variants reported so far shows that the vast majority of variants causing PFIC3 and LPAC are distinct. Also as a general rule, homozygous variants cause PFIC3 while heterozygous variants lead to LPAC. Combined PFIC3 and LPAC phenotype is a rare clinical event, which may be determined by the coexistence of ABCB4 variants related to both phenotypes and also potentially to the ABCB11 variant. Thus, most of the patients presenting with LPAC are not at a particular risk of developing PFIC3 features in adulthood.