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Exome sequencing (ES) has identified biallelic kinesin family member 12 (KIF12) mutations as underlying neonatal cholestatic liver disease. We collected information on onset and progression of this entity. Among consecutively referred pediatric patients at our centers, diagnostic ES identified 4 patients with novel, biallelic KIF12 variants using the human GRCh38 reference sequence, as KIF12 remains incompletely annotated in the older reference sequence GRCh37. A review of these and of 21 reported patients with KIF12 variants found that presentation with elevated serum transaminase activity in the context of trivial respiratory infection, without clinical features of liver disease, was more common (n = 18) than manifest cholestatic disease progressing rapidly to liver transplantation (LT; n = 7). Onset of liver disease was at age <1 year in 15 patients; LT was more common in this group. Serum gamma-glutamyl transpeptidase activity (GGT) was elevated in all patients, and total bilirubin was elevated in 15 patients. Liver fibrosis or cirrhosis was present in 14 of 18 patients who were biopsied. The 16 different pathogenic variants and 11 different KIF12 genotypes found were not correlated with age of onset or progression to LT. Identification of biallelic pathogenic KIF12 variants distinguishes KIF12-related disease from other entities with elevated GGT., (© 2024 The Authors. Clinical Genetics published by John Wiley & Sons Ltd.)

Background: For many children with intrahepatic cholestasis and high-serum gamma-glutamyl transferase (GGT) activity, a genetic aetiology of hepatobiliary disease remains undefined. We sought to identify novel genes mutated in children with idiopathic high-GGT intrahepatic cholestasis, with clinical, histopathological and functional correlations., Methods: We assembled a cohort of 25 children with undiagnosed high-GGT cholestasis and without clinical features of biliary-tract infection or radiological features of choledochal malformation, sclerosing cholangitis or cholelithiasis. Mutations were identified through whole-exome sequencing and targeted Sanger sequencing. We reviewed histopathological findings and assessed phenotypical effects of ZFYVE19 deficiency in cultured cells by immunofluorescence microscopy., Results: Nine Han Chinese children harboured biallelic, predictedly complete loss-of-function pathogenic mutations in ZFYVE19 (c.314C>G, p.S105X; c.379C>T, p.Q127X; c.514C>T, p.R172X; c.547C>T, p.R183X; c.226A>G, p.M76V). All had portal hypertension and, at liver biopsy, histopathological features of the ductal plate malformation (DPM)/congenital hepatic fibrosis (CHF). Four children required liver transplantation for recurrent gastrointestinal haemorrhage. DPM/CHF was confirmed at hepatectomy, with sclerosing small-duct cholangitis. Immunostaining for two primary-cilium axonemal proteins found expression that was deficient intraluminally and ectopic within cholangiocyte cytoplasm. ZFYVE19 depletion in cultured cells yielded abnormalities of centriole and axoneme., Conclusion: Biallelic ZFYVE19 mutations can lead to high-GGT cholestasis and DPM/CHF in vivo. In vitro, they can lead to centriolar and axonemal abnormalities. These observations indicate that mutation in ZFYVE19 results, through as yet undefined mechanisms, in a ciliopathy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Aims: Progressive familial intrahepatic cholestasis (PFIC) 6 has been associated with missense but not biallelic nonsense or frameshift mutations in MYO5B, encoding the motor protein myosin Vb (myoVb). This genotype-phenotype correlation and the mechanism through which MYO5B mutations give rise to PFIC are not understood. The aim of this study was to determine whether the loss of myoVb or expression of patient-specific myoVb mutants can be causally related to defects in canalicular protein localization and, if so, through which mechanism., Approach and Results: We demonstrate that the cholestasis-associated substitution of the proline at amino acid position 600 in the myoVb protein to a leucine (P660L) caused the intracellular accumulation of bile canalicular proteins in vesicular compartments. Remarkably, the knockout of MYO5B in vitro and in vivo produced no canalicular localization defects. In contrast, the expression of myoVb mutants consisting of only the tail domain phenocopied the effects of the Myo5b-P660L mutation. Using additional myoVb and rab11a mutants, we demonstrate that motor domain-deficient myoVb inhibited the formation of specialized apical recycling endosomes and that its disrupting effect on the localization of canalicular proteins was dependent on its interaction with active rab11a and occurred at the trans-Golgi Network/recycling endosome interface., Conclusions: Our results reveal a mechanism through which MYO5B motor domain mutations can cause the mislocalization of canalicular proteins in hepatocytes which, unexpectedly, does not involve myoVb loss-of-function but, as we propose, a rab11a-mediated gain-of-toxic function. The results explain why biallelic MYO5B mutations that affect the motor domain but not those that eliminate myoVb expression are associated with PFIC6., (© 2019 The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of American Association for the Study of Liver Diseases.)

NGLY1 deficiency is the first and only autosomal recessive congenital disorder of N-linked deglycosylation (NGLY1-CDDG). To date, no patients with NGLY1 deficiency has been reported from mainland China or East Asia in English literature. Here, we present six patients with a diagnosis of NGLY1-CDDG on the basis of clinical phenotype, genetic testing, and functional studies. We retrospectively analyzed clinical phenotypes and NGLY1 genotypes of six cases from four families. Informed consent was obtained for diagnosis and treatment. In-silico tools and in vitro enzyme activity assays were used to determine pathogenicity of NGLY1 varaints. All patients had typical features of NGLY1-CDDG, including global developmental delay, microcephaly, hypotonia, hypertransaminasemia, alacrimia, and feeding difficulty. Dysmorphic features found in our patients include flat nasal bridge, loose and hollow cheeks, short stature, malnutrition, and ptosis. Pachylosis could be a novel cutaneous feature that may be explained by lack of sweat. We found three novel variants, including one missense (c.982C > G/p.Arg328Gly), one splice site (c.1003+3A > G), and one frame-shift (c.1637-1652delCATCTTTTGCTTATAT/p.Ser546PhefsTer) variant. All mutations were predicted to be disease causing with in-silico prediction tools, and affected at least one feature of gene splicing. Protein modeling showed missense variants may affect covalent bonding within the protein structure, or interrupt active/binding amino-acid residues. In vitro studies indicated that proteins carrying missense variants (p.Arg328Gly and p.Tyr342Cys) lost the enzyme activity. We expanded clinical phenotype and genetic mutation spectrum of NGLY1-CDDG by reporting six cases, three novel variants, and novel clinical features from mainland China.

Background: Genetic defects account for a substantial proportion of pediatric cholestasis. This study explored the molecular findings in a large cohort of Chinese patients with inherited cholestasis., Methods: Between January 2012 and June 2016, 809 Chinese pediatric patients with suspected inherited intrahepatic cholestasis were evaluated by Sanger sequencing and/or panel sequencing., Results: Of the 809 patients, 273 (33.7%) obtained a genetic diagnosis. The rate of positive genetic diagnosis in patients with disease onset at 0-3 month of age was higher than that in patients with disease onset at 4 month of age or later. There were 17 distinct genetic defects diagnosed. The top 4 resulted from mutations in SLC25A13 (44.3%), JAG1 (24.5%), ABCB11 (11.0%), and ATP8B1 (5.9%). All 17 genetic disorders were diagnosed in patients with disease onset at 0-3 months of age; but only 5 were diagnosed in patients with disease onset beyond 4 months of age. A total of 217 distinct pathogenic variants, including 41 novel variants, were identified. Ten recurrent mutations were detected in SLC25A13, ATP8B1, and CYP27A1. They accounted for 48.2% of the total 477 mutant alleles., Conclusions: There were 17 distinct genetic disorders diagnosed in Chinese pediatric patients with inherited cholestasis.

Pediatric acute liver failure (ALF) is life threatening with genetic, immunologic, and environmental etiologies. Approximately half of all cases remain unexplained. Recurrent ALF (RALF) in infants describes repeated episodes of severe liver injury with recovery of hepatic function between crises. We describe bi-allelic RINT1 alterations as the cause of a multisystem disorder including RALF and skeletal abnormalities. Three unrelated individuals with RALF onset ≤3 years of age have splice alterations at the same position (c.1333+1G>A or G>T) in trans with a missense (p.Ala368Thr or p.Leu370Pro) or in-frame deletion (p.Val618&#95;Lys619del) in RINT1. ALF episodes are concomitant with fever/infection and not all individuals have complete normalization of liver function testing between episodes. Liver biopsies revealed nonspecific liver damage including fibrosis, steatosis, or mild increases in Kupffer cells. Skeletal imaging revealed abnormalities affecting the vertebrae and pelvis. Dermal fibroblasts showed splice-variant mediated skipping of exon 9 leading to an out-of-frame product and nonsense-mediated transcript decay. Fibroblasts also revealed decreased RINT1 protein, abnormal Golgi morphology, and impaired autophagic flux compared to control. RINT1 interacts with NBAS, recently implicated in RALF, and UVRAG, to facilitate Golgi-to-ER retrograde vesicle transport. During nutrient depletion or infection, Golgi-to-ER transport is suppressed and autophagy is promoted through UVRAG regulation by mTOR. Aberrant autophagy has been associated with the development of similar skeletal abnormalities and also with liver disease, suggesting that disruption of these RINT1 functions may explain the liver and skeletal findings. Clarifying the pathomechanism underlying this gene-disease relationship may inform therapeutic opportunities., (Copyright © 2019 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Background: Underlying causes in Chinese children with recurrent acute liver failure (RALF), including liver crises less than full acute liver failure, are incompletely understood. We sought to address this by searching for genes mutated in such children., Methods: Five unrelated Chinese boys presenting between 2012 and 2015 with RALF of unexplained etiology were studied. Results of whole exome sequencing were screened for mutations in candidate genes. Mutations were verified in patients and their family members by Sanger sequencing. All 5 boys underwent liver biopsy., Results: NBAS was the only candidate gene mutated in more than one patient (biallelic mutations, 3 of 5 patients; 5 separate mutations). All NBAS mutations were novel and predictedly pathogenic (frameshift insertion mutation c.6611&#95;6612insCA, missense mutations c.2407G > A and c.3596G > A, nonsense mutation c.586C > T, and splicing-site mutation c.5389 + 1G > T). Of these mutations, 3 lay in distal (C-terminal) regions of NBAS, a novel distribution. Unlike the 2 patients without NBAS mutations, the 3 patients with confirmed NBAS mutations all suffered from a febrile illness before each episode of liver crisis (fever-related RALF), with markedly elevated alanine aminotransferase and aspartate aminotransferase activities 24-72 h after elevation of body temperature, succeeded by severe coagulopathy and mild to moderate jaundice., Conclusions: As in other countries, so too in China; NBAS disease is a major cause of fever-related RALF in children. The mutation spectrum of NBAS in Chinese children seems different from that described in other populations.

Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome (OMIM 208085) is an autosomal recessive disorder that is caused by mutations in 2 interacting genes VPS33B and VIPAS39. Mutations in VPS33B gene account for most cases of ARC. As low or normal gamma-glutamyl transpeptidase (GGT) activity has been described in all patients with ARC syndrome identified so far, ARC syndrome is a possible diagnosis for low GGT cholestasis. Here we describe a Chinese patient with neonatal cholestasis and a high GGT level in three consecutive tests. She had other typical manifestations of ARC syndrome, including arthrogryposis multiplex congenita, renal involvement and ichthyosis. Genetic study of the VPS33B gene further confirmed the diagnosis by identification of compound heterozygosity of two known disease-causing mutations, c.403+2T > A and c.1509-1510insG. The mechanism of high GGT in this patient is unclear. Nevertheless, this case indicates that ARC syndrome cannot be excluded from the differential diagnosis of neonatal cholestasis even if high GGT activity is found.

Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome is a rare genetic disorder and has not been described in China. We present a female infant with neonatal intrahepatic cholestasis from a Chinese family with ARC syndrome. All 23 coding exons and flanking introns of the VPS33B gene were amplified and sequenced using peripheral lymphocyte genomic DNA of the patient and her parents. Genetic testing revealed two novel mutations (c.1033delA and c.1567C>T) in the VPS33B gene. The patient is a compound heterozygote and her parents were heterozygous for each of the mutations.

Aim: To investigate the differences in the mutation spectra of the SLC25A13 gene mutations from specific regions of China., Methods: Genetic analyses of SLC25A13 mutations were performed in 535 patients with neonatal intrahepatic cholestasis from our center over eight years. Unrelated infants with at least one mutant allele were enrolled to calculate the proportion of SLC25A13 mutations in different regions of China. The boundary between northern and southern China was drawn at the historical border of the Yangtze River., Results: A total of 63 unrelated patients (about 11% of cases with intrahepatic cholestasis) from 16 provinces or municipalities in China had mutations in the SLC25A13 gene, of these 16 (25%) were homozygotes, 28 (44%) were compound heterozygotes and 19 (30%) were heterozygotes. In addition to four well described common mutations (c.851&#95;854del, c.1638&#95;1660dup23, c.615+5G>A and c.1750+72&#95;1751-4dup17insNM&#95;138459.3:2667 also known as IVS16ins3kb), 13 other mutation types were identified, including three novel mutations: c.985&#95;986insT, c.287T>C and c.1349A>G. According to the geographical division criteria, 60 mutant alleles were identified in patients from the southern areas of China, 43 alleles were identified in patients from the border, and 4 alleles were identified in patients from the northern areas of China. The proportion of four common mutations was higher in south region (56/60, 93%) than that in the border region (34/43, 79%, χ(2) = 4.621, P = 0.032) and the northern region (2/4, 50%, χ(2) = 8.288, P = 0.041)., Conclusion: The SLC25A13 mutation spectra among the three regions of China were different, providing a basis for the improvement of diagnostic strategies and interpretation of genetic diagnosis.

Objective: To investigate the clinical features and mutations of the FAH gene., Method: Clinical records of two cases were collected, and diagnosis was made according to the diagnostic criteria of the International Organization for Rare Disorders (NORD). Genomic DNA was extracted from peripheral blood leukocytes with QIAamp DNA Mini Kit. The DNA extracts were subjected to direct sequencing for 14 exons together with adjacent fragments of FAH gene using ABI Prism 3730 Genetic Analyzer (Applied Biosystems, Foster City, CA) after PCR based on genomic DNA. The mutation source was verified by analyzing parents' exons corresponding to patients' mutation exons. The homology between human FAH enzyme and that of other species was surveyed using software Clustal X(European Bioinformatics Institute, Hinxton, Saffron Walde, UK). Polyphen (Polymorphism Phenotyping), available online, were used to predict possible impact of an amino acid substitution on structure and function of FAH enzyme. Polyphen calculates position-specific independent counts (PISC) scores for two amino acid variants in polymorphic position. A PISC scores that differ by > 2 were regarded as indicating the probability of damaging variants., Result: Patient 1 was a 5 months and 21 days-old boy who suffered from persistent diarrhea, hepatomegaly, ascites; Alpha-fetoprotein > 1210 µg/L, levels of tyrosine in blood and succinylacetone in urine were 110.8 µmol/L and 83.7 µmol/L. His sister suffered from tyrosinemia type 1. Direct sequencing showed a G to A transition in CDS position 455 and 1027. He was compound heterozygous for the mutation c.455G > A/c.1027G > A, which predicts a change from tryptophan to a stop codon (TGG > TAG) at position 152 (W152X) and a change from glycine to arginine (GGG > AGG) at position 343 respectively. Patient 2 was a 6 year and 1 month-old girl with late-onset rickets who had signs of hepatosplenomegaly, rachitic rosary, windswept knees. Hypophosphatemia and alkaline phosphatase 1620 IU/L were detected. Alpha-fetoprotein 412.8 µg/L, levels of tyrosine in blood and succinylacetone in urine were 835.8 µmol/L and 27.48 µmol/L. Rickets did not improve after administration of calcium and vitamine D3. She is homozygous for the mutation c.1027G > A/c.1027G > A, which predicts G343R. The parents were mutation carriers. Analysis by Clustal X on the alignment of amino acids residual reservation among different species showed that the locative amino acid was highly conserved. Polyphen software predicted G343R was probably damaging (PISC score 3.235)., Conclusion: Children with tyrosinemia type 1 can have manifestations of persistent diarrhea or late-onset rickets. Physical examination can reveal hepatosplenomegaly, laboratory tests indicate markedly elevated serum concentration of alpha-fetoprotein and alkaline phosphatase in plasma and succinylacetone in urine, other members in family may have tyrosinemias or parents are consanguineous. Mutations c.455G > A and c.1027G > A can be detected in FAH gene of Chinese children.

Background: The significance of ABCB11 variants have been studied in some cholestatic diseases, but this is not clear in transient neonatal cholestasis (TNC). The aim of the present study was to explore the association between ABCB11 variants and TNC., Methods: This was a case-control study. A total of 192 children with TNC referred to a tertiary referral hospital in eastern China were enrolled as subjects, and 196 healthy children were selected as controls. Part of the promoter and exons of the ABCB11 gene were sequenced directly. The single nucleotide polymorphism (SNP) site of V444A was tested using fluorescent quantitative polymerase chain reaction. Potential consequences of variants were predicted using bioinformatics software. The biochemistry indices were compared between the patients with or without possibly pathogenic variants/mutations., Results: Twenty-eight variants, including 14 novel ones, were detected. Four novel, possibly pathogenic mutations (I416I, K436N, R928Q and IVS7+5G>A) were detected in six subjects. The γ-glutamyltransferase level of these six was lower than in the others (P = 0.054). The genotype distribution of the four common SNP sites, V444A, A535A, A865V and A1082A, was not significantly different between TNC patients and controls., Conclusions: Approximately 3% of TNC cases can be attributed to ABCB11 mutations., (© 2013 The Authors. Pediatrics International © 2013 Japan Pediatric Society.)

Objective: The aims of the present study was to study the significance of ABCB4 mutations in mainland Chinese children with chronic intrahepatic cholestasis and to correlate genetic findings with clinical features and response to ursodeoxycholic acid (UDCA) therapy., Methods: Thirteen patients with chronic intrahepatic cholestasis and elevated serum γ-glutamyl transpeptidase activity of unknown cause were enrolled in a single pediatric center. All of the encoding exons and flanking areas of ABCB4 were sequenced. Available liver biopsy specimens were immunostained for multidrug resistance protein 3. The clinical features, biochemical parameters, and responses to therapy were compared with patients with or without ABCB4 mutation(s)., Results: Six different ABCB4 mutations were identified in 3 patients; each patient was a compound heterozygote. Apart from c.139C>T (p.R47X), all were novel, including c.344+2&#95;+3insT, c.1376A>G (p.D459G), c.1745G>A (p.R582Q), c.2077&#95;2078delC (p.P693HfsX698), and c.3825&#95;3826delA (p.M1276WfsX1308). Absent or reduced multidrug resistance protein 3 canalicular immunostaining was demonstrated in patients with ABCB4 mutations. Serum total bile acid levels were higher in patients with ABCB4 mutations than in patients without ABCB4 mutations (352.5 ± 97.0 vs 55.9 ± 50.4 μmol/L, P = 7.32E-05). There was no difference in other biochemical parameters between patients with and without ABCB4 mutations. After oral UDCA administration in 3 patients with ABCB4 mutations, pruritus disappeared, growth improved, spleen size decreased, and platelet counts increased. In the 10 patients without ABCB4 mutations, an inconsistent response to UDCA therapy was observed., Conclusions: In mainland Chinese children, some cases of chronic intrahepatic cholestasis with high γ-glutamyl transpeptidase could be attributed to ABCB4 mutations. UDCA administration partially improved clinical symptoms and liver function.

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 gamma 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.

Objectives: The aim of the study was to elucidate the role and characteristics of ATP8B1 gene mutations in mainland Chinese children with progressive intrahepatic cholestasis and low gamma-glutamyltransferase (GGT)., Patients and Methods: Twenty-four children who presented with progressive intrahepatic cholestasis and low GGT were admitted to a tertiary pediatric hospital in eastern China from January 2004 to July 2007. Five children with homozygous or compound heterozygous ABCB11 gene mutations were excluded from the study. All encoding exons and their flanking areas of ATP8B1 gene were sequenced in the remaining 19 patients, in whom only 1 or no mutation of ABCB11 was found. Clinical features and liver histology obtained by reviewing the medical records were compared among patients with different genotypes., Results: Nine mutations of ATP8B1 gene were found in 9 patients. All of them were novel except for mutations I694N and R952X. A linked P209T and IVS6+5G>T mutation was found in 4 of 9 patients, including 2 homozygotes and 2 heterozygotes. Giant cell transformation of hepatocytes was demonstrated in 1 of 6 patients with ATP8B1 mutations and 4 of 5 patients with ABCB11 mutations., Conclusions: ATP8B1 gene mutations play an important role in Chinese patients with progressive intrahepatic cholestasis and low GGT. The linked mutation P209T and IVS6+5G>T is a hot mutation in the Chinese population. Histological examination may be helpful in differentiating familial intrahepatic cholestasis type 1 from bile salt export pump-related disease.

Objective: To explore whether SLC25A13 gene mutation exists and what is its mutation spectrum in mainland Chinese infants with intrahepatic cholestasis and abnormal blood amino acids., Methods: Blood amino acids were analyzed by mass chromatographic analysis in infants referred to Fudan University Children's Hospital from June 2003 to June 2007 for investigations of intrahepatic cholestasis of unknown origin. SLC25A13 gene mutations were studied in 14 children whose serum levels of citrulline and/or methionine were at least two times above the upper normal range. In patients in whom only one mutation was detected, all other exons and their neighboring sequences were then analyzed., Results: Eight patients with SLC25A13 gene mutations, including 2 with compound heterozygous mutation 851del4/1638ins23, one with homozygous mutation 851del4/851del4, one with compound heterozygous mutation 851del4/R184X, one with homozygous mutation IVS6+1G more than A/IVS6+1G more than A, and 3 with heterozygous mutation 851del4 were found., Conclusions: SLC25A13 gene mutations exist in Chinese infants with intrahepatic cholestasis and abnormal blood amino acids. Their mutation spectrum is different from that in Japan. 851del4 is the most common mutation in our study. IVS6+1G more than A is a mutation that has not been reported before.

Background: TMEM199-congenital disorder of glycosylation (TMEM199-CDG) is a rare autosomal recessive inherited disease characterized by chronically elevated serum transaminase, decreased serum ceruloplasmin, steatosis and/or fibrosis, TMEM199 mutation, reduced level of TMEM199 protein, and abnormal protein glycosylation. Methods: The information of a Chinese patient with TMEM199-CDG in the Children's Hospital of Fudan University was reviewed. The patient's clinical, pathological, and molecular features were obtained by clinical data study, liver biopsy, immunohistochemistry, and molecular genetic analysis. Results: A 4-year-old Chinese boy presented with hypertransaminasemia, hypercholesterolemia, elevated alkaline phosphatase, decreased serum ceruloplasmin and serum copper level, and coagulopathy since birth. To the best of our knowledge, novel findings included strabismus, cirrhosis by liver biopsy, reduced expression of TMEM199 by immunohistochemistry, and a frameshift variant of c.128delA/p.Lys43Argfs*25 in the TMEM199 gene. Conclusion: This case added to the phenotypic and genotypic spectrum of TMEM199-CDG. [ABSTRACT FROM AUTHOR]

Background and Aims: Large indels are commonly identified in patients but are not detectable by routine Sanger sequencing and panel sequencing. We specially designed a multi-gene panel that could simultaneously test known large indels in addition to ordinary variants, and reported the diagnostic yield in patients with intrahepatic cholestasis. Methods: The panel contains 61 genes associated with cholestasis and 25 known recurrent large indels. The amplicon library was sequenced on Ion PGM system. Sequencing data were analyzed using a routine data analysis protocol and an internal program encoded for large indels test simultaneously. The validation phase was performed using 54 patients with known genetic diagnosis, including 5 with large insertions. At implement phase, 141 patients with intrahepatic cholestasis were evaluated. Results: At validation phase, 99.6% of the variations identified by Sanger sequencing could be detected by panel sequencing. Following the routine protocol, 99.8% of false positives could be filtered and 98.8% of retained variations were true positives. Large insertions in the 5 patients with known genetic diagnosis could be correctly detected using the internal program. At implementation phase, 96.9% of the retained variations, following the routine protocol, were confirmed to be true. Twenty-nine patients received a potential genetic diagnosis when panel sequencing data were analyzed using the routine protocol. Two additional patients, who were found to harbor large insertions in SLC25A13, obtained a potential genetic diagnosis when sequencing data were further analyzed using the internal program. A total of 31 (22.0%) patients obtained a potential genetic diagnosis. Nine different genetic disorders were diagnosed, and citrin deficiency was the commonest. Conclusion: Specially designed multi-gene panel can correctly detect large indels simultaneously. By using it, we assigned a potential genetic diagnosis to 22.0% of patients with intrahepatic cholestasis. [ABSTRACT FROM AUTHOR]

Background and Aims: Genetic defects in ATP8B1 or ABCB11 account for the majority of cholestasis with low GGT. But the ranges for GGT in patients with ATP8B1 or ABCB11 deficiency are unclear. This study tried to unravel the features of GGT in these patients that improve diagnostic efficiency. Methods: This study enrolled 207 patients with chronic cholestasis who were ordered to test for ATP8B1 and/or ABCB11 from January 2012 to December 2015. Additional 17 patients with ATPB81 or ABCB11 deficiency diagnosed between January 2004 and December 2011 were also enrolled in this study. 600 population-matched children served as controls. Clinical data were obtained by retrospectively reviewing medical records. Results: A total of 26 patients were diagnosed with ATP8B1 deficiency and 30 patients were diagnosed with ABCB11 deficiency. GGT levels were similar between the two disorders at any observed month of age, but varied with age. The peak GGT value was <70U/L in the 2nd~6th month of life, <60U/L in the 7th~12th month and <50U/L beyond one year. GGT levels in patients with a genetic diagnosis were different from that in patients without a genetic diagnosis and controls. Larger ranges for GGT were found in patients without a genetic diagnosis. Some controls had GGT≥70U/L in the 2nd~6th month. Of the 207 patients, 39 (18.8%) obtained a genetic diagnosis. 111 patients met the ranges described above, including all the 39 patients with ATP8B1 or ABCB11 deficiency. The sensitivity was 100.0%. The rate of a positive molecular diagnosis increased to 35.1% (39/111 vs. 39/207, X2 = 10.363, P = 0.001). The remaining 96 patients exceeded the ranges described above and failed to receive a genetic diagnosis. These patients accounted for 43.8% of sequencing cost. Conclusions: GGT levels in patients with ATP8B1 or ABCB11 deficiency varied with age. The peak GGT value was <70U/L in the 2nd~6th month of life, <60U/L in the 7th~12th month and <50U/L beyond one year. [ABSTRACT FROM AUTHOR]