Biochemical characteristics of neonatal cholestasis induced by citrin deficiency

Biochemical characteristics, genetic variants and treatment outcomes of 55 Chinese cases with neonatal intrahepatic cholestasis caused by citrin deficiency

Background

The diagnostic criteria of neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) have not been established due to non-specific clinical manifestations, and our understanding on the treatment outcome is still limited. We aim to investigate the biochemical characteristics, genetic variants, and treatment outcome of NICCD patients.

Methods

We compared the nutritional status and biochemical characteristics of 55 NICCD infants and 27 idiopathic neonatal cholestasis (INC) infants. SLC25A13 gene variant analysis was performed for definitive diagnosis of NICCD. NICCD infants received 12 months of lactose-free and/or medium-chain triglyceride-enriched (LF/MCT) formula treatment. The treatment efficacy was evaluated by comparing the outcome of NICCD with the 24 healthy infants that were selected as normal controls. All NICCD patients were followed up until death or at least 1 year of age.

Results

Compared to INC group, significant increase was found in levels of total bilirubin, indirect bilirubin, total bile acid, gamma-glutamyl transpeptidase, alkaline phosphatase, prothrombin time, thrombin time, international normalized ratio, alpha-fetoprotein (AFP), Vitamin D, and Vitamin E of NICCD group, while alanine aminotransferase, albumin, fibrinogen, glucose, and Vitamin A levels showed significant decrease in the NICCD group (P < 0.05). There were 7 novel variants among 19 SLC25A13 variant types. No significant differences were found between NICCD patients treated for 12 months and normal controls. In long term follow-up, 2 cases developed FTTDCD, 8 cases had special dietary habits, and 1 case died from cirrhosis.

Conclusions

NICCD showed more severe impairments in liver, coagulation, and metabolic function than INC. Significantly increased AFP levels could provide reference for the differential diagnosis of NICCD. The newly discovered variants may be meaningful for the individualized treatment of NICCD patients. LF/MCT formula was recommended for NICCD patients.

Diagnostic algorithm for neonatal intrahepatic cholestasis integrating single-gene testing and next-generation sequencing in East Asia

BACKGROUND AND AIM

Advances in molecular genetics have uncovered causative genes responsible for neonatal cholestasis. Panel-based next-generation sequencing has been used clinically in infants with neonatal cholestasis. We aimed to evaluate the clinical application of single-gene testing and next-generation sequencing and to develop a diagnostic algorithm for neonatal intrahepatic cholestasis.

METHODS

From January 2010 to July 2021, patients suspected of having neonatal intrahepatic cholestasis were tested at the Seoul National University Hospital. If there was a clinically suspected disease, single-gene testing was performed. Alternatively, if it was clinically difficult to differentiate, a neonatal cholestasis gene panel test containing 34 genes was performed.

RESULTS

Of the total 148 patients examined, 49 (33.1%) were received a confirmed genetic diagnosis, including 14 with Alagille syndrome, 14 with neonatal intrahepatic cholestasis caused by citrin deficiency, 7 with Dubin-Johnson syndrome, 5 with arthrogryposis-renal dysfunction-cholestasis syndrome, 5 with progressive familial intrahepatic cholestasis type II, 1 with Rotor syndrome, 1 with Niemann-Pick disease type C, 1 with Kabuki syndrome, and 1 with Phenylalanyl-tRNA synthetase subunit alpha mutation. Sixteen novel pathogenic or likely pathogenic variants of neonatal cholestasis were observed in this study. Based on the clinical characteristics and laboratory findings, we developed a diagnostic algorithm for neonatal intrahepatic cholestasis by integrating single-gene testing and next-generation sequencing.

CONCLUSIONS

Alagille syndrome and neonatal intrahepatic cholestasis caused by citrin deficiency were the most common diseases associated with genetic neonatal cholestasis. Single-gene testing and next-generation sequencing are important and complementary tools for the diagnosis of genetic neonatal cholestasis.

Features of liver injury in 138 Chinese patients with NICCD

OBJECTIVES

To find biochemical and molecular markers can assist in identifying serious liver damage of neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) patients.

METHODS

138 patients under 13 days to 1.1 year old diagnosed of NICCD in our center from 2004 to 2020. Base on the abnormal liver laboratory tests, we divided 138 patients into three groups: acute liver failure (ALF), liver dysfunction, and non-liver dysfunction groups, then compared their clinical, biochemical and, molecular data.

RESULTS

96 % of 138 patients had high levels of citrulline and high ratio of threonine to serine, which is the distinctive feature of plasma amino acid profile for NICCD. A total of 18.1 % of 138 patients had evidence of ALF who presented the most severity hepatic damage, 51.5 % had liver dysfunction, and the remaining 30.4 % presented mild clinical symptoms (non-liver dysfunction). In ALF group, the levels of citrulline, tyrosine, TBIL, ALP, and γ-GT was significantly elevated, and the level of ALB and Fisher ratio was pronounced low. Homozygous mutations of 1,638_1660dup, IVS6+5G.A, or IVS16ins3kb in SLC25A13 gene were only found in ALF and liver dysfunction groups. Supportive treatment including medium-chain triglyceride supplemented diet and fresh frozen plasma could be life-saving and might reverse ALF.

CONCLUSIONS

High level of citrulline, tyrosine, TBIL, ALP, γ-GT, and ammonia, low level of albumin, and low Fisher ratio were predictors to suggest severe liver damage in NICCD patients who may go on to develop fatal metabolic disorder. Early identification and proper therapy is particularly important for these patients.

Dynamic changes of metabolic characteristics in neonatal intrahepatic cholestasis caused by citrin deficiency

Introduction: Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is a pan-ethnic complicated inborn error of metabolism but the specific mechanism is not fully understood.

Methods: A total of 169 patients with NICCD who have biallelic pathogenic SLC25A13 variants detected by targeted next-generation sequencing were collected. They were divided into the “Newborn-screen Group” and “Clinical diagnosed Group” depending on the newborn screening results. Amino acid and acylcarnitine profiles were measured by MS/MS. The total bile acids, blood amino acids and acylcarnitines, general biochemistry, blood count, and coagulation parameters were monitored every 2–3 months. We compared the differences in metabolic indices and their dynamic changes between these two groups. The Mann–Whitney test and orthogonal partial least squares discrimination analysis (OPLS-DA) were used for statistical analysis.

Results: At the onset of NICCD, we found that the “Clinical diagnosed Group” had higher levels of intermediate products of the urea cycle, free carnitine, and short-chain and long-chain acylcarnitines than those in the “Newborn-screen Group,” but the levels of ketogenic/glucogenic amino acids and several medium-chain acylcarnitines were lower. Furthermore, concentrations of direct bilirubin, total bile acid, lactate, prothrombin time, and several liver enzymes were significantly higher while total protein, amylase, and hemoglobin were lower in the “Clinical diagnosed Group” than in the “Newborn-screen Group.” Dynamic change analysis showed that direct bilirubin, albumin, arginine, and citrulline were the earliest metabolic derangements to reach peak levels in NICCD groups, followed by acylcarnitine profiles, and finally with the elevation of liver enzymes. All abnormal characteristic metabolic indicators in the “Newborn-screen Group” came back to normal levels at earlier ages than the “Clinical diagnosed Group.” c.852_855del (41.2%), IVS16ins3kb (17.6%), c.615 + 5G&gt;A (9.6%), 1638_1660dup (4.4%), and c.1177 + 1G&gt;A (3.7%) accounted for 76.5% of all the mutated SLC25A13 alleles in our population.

Conclusion: Argininosuccinate synthesis, gluconeogenesis, ketogenesis, fatty acid oxidation, liver function, and cholestasis were more severely affected in the “Clinical diagnosed Group.” The “Newborn-screen Group” had a better prognosis which highlighted the importance of newborn screening of NICCD.

Hemostatic rebalance in neonatal intrahepatic cholestasis with citrin deficiency

BACKGROUND

Neonatal intrahepatic cholestasis with citrin deficiency (NICCD) results in coagulopathy due to decreased levels of vitamin (V)K-dependent clotting factors, similar to biliary atresia (BA). However, the involvement of VK-independent coagulant and anticoagulant factor(s) remains unknown. We examined relationships between coagulant and anticoagulant potential before and after nutritional treatment in NICCD.

METHODS

Three cases (aged 12, 21, and 45 days) with NICCD-associated coagulopathy were evaluated with standard coagulation/anticoagulation tests and comprehensive coagulation assays, rotational thromboelastometry, and protein C/protein S (PC/PS) pathway function assay (ThromboPath^® ), before and after nutritional treatment.

RESULTS

In all cases, activated partial thromboplastin time and prothrombin time were significantly prolonged, which is associated with very low levels of VK-independent fibrinogen and antithrombin. The initiation of nutritional treatment of medium-chain triglycerides oil improved these levels within the normal range, although low levels of other clotting factors were modestly increased. Whole blood- rotational thromboelastometry analysis revealed near-normal coagulation potential, even before treatment, comparable to healthy adults, and supportive of their non-bleeding symptoms. The introduction of nutritional treatment had further improved comprehensive coagulation potential. The global PC/PS-pathway function assay demonstrated the absence of the features of this function associated with the pathogenesis of NICCD. Compared to BA, the plasma levels of fibrinogen and antithrombin in all cases were markedly low, whilst those after treatment improved, especially to similar level of BA.

CONCLUSIONS

Neonatal intrahepatic cholestasis with citrin deficiency has the characteristic of rebalancing hemostatic mechanisms associated with coagulant and anticoagulant potential involving low levels of fibrinogen and antithrombin, suggesting a pathophysiological coagulopathy distinct from BA.

Clinical characteristics and genetic analysis of neonatal intrahepatic cholestasis caused by citrin deficiency in comparison with idiopathic neonatal cholestasis

To compare the clinical and genetic characteristics of patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and idiopathic neonatal cholestasis (INC). The clinical data of 30 patients with NICCD and 30 patients with INC admitted in Children's Hospital of Chongqing Medical University during September 2012 and December 2017 were retrospectively analyzed. The clinical manifestations, biochemical indicators and genetic characteristics were compared between two groups. Patients in both groups presented similar clinical manifestations, however the chubby face and clay-colored stool were more common in NICCD patients (both <0.01). Comparing with INC group, NICCD group showed significantly decreased blood levels of glucose, prealbumin, albumin, total protein, fibrinogen, and aminotransferases (<0.05 or <0.01), while significantly increased blood levels of indirect bilirubin, total bile acid, alkaline phosphatase, lactic dehydrogenase, ammonium, alpha fetoprotein, and markers of coagulation function (<0.05 or <0.01). In addition, NICCD patients showed remarkably increased blood levels of citrulline, methionine, tyrosine, arginine, and threonine; as well as significantly increased urine levels of 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvic acid and phenyllactic acid, while those indicators in INC patients were normal (all <0.01). All the patients with NICCD had mutation including 8 homozygotes, 9 compound heterozygotes, and 13 single heterozygotes. Among all mutations, c.851_854del was most common (53.19%), c.1196T>A and c.919G>T were two novel mutations. The manifestations of chubby face and clay-colored stool may provide clue for early diagnosis of NICCD along with the elevated biochemical parameters, such as ammonium, alpha-fetal protein, citrulline in blood and 4-hydroxyphenyllactic acid, 4-hydroxyphenylpyruvic acid, phenyllactic acid in urine. Target gene trapping and high-throughput sequencing have the key values in diagnosis and differential diagnosis of NICCD.

Citrin deficiency mimicking mitochondrial depletion syndrome

Background

Neonatal intrahepatic cholestasis caused by citrin deficiency (CD) is a rare inborn error of metabolism due to variants in the SLC25A13 gene encoding the calcium-binding protein citrin. Citrin is an aspartate-glutamate carrier located within the inner mitochondrial membrane.

Case presentation

We report on two siblings of Romanian-Vietnamese ancestry with citrin deficiency. Patient 1 is a female who presented at age 8 weeks with cholestasis, elevated lactate levels and recurrent severe hypoglycemia. Diagnosis was made by whole exome sequencing and revealed compound heterozygosity for the frameshift variant c.852_855del, p.Met285Profs*2 and a novel deletion c.(69 + 1_70–1)_(212 + 1_231–1)del in SLC25A13. The girl responded well to dietary treatment with a lactose-free, MCT-enriched formula. Her younger brother (Patient 2) was born 1 year later and also found to be carrying the same gene variants. Dietary treatment from birth was able to completely prevent clinical manifestation until his current age of 4.5 months.

Conclusions

As CD is a well-treatable disorder it should be ruled out early in the differential diagnosis of neonatal cholestasis. Due to the combination of hepatopathy, lactic acidosis and recurrent hypoglycemia the clinical presentation of CD may resemble hepatic mitochondrial depletion syndrome.

Molecular findings in children with inherited intrahepatic cholestasis

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.

Analysis of islet beta cell functions and their correlations with liver dysfunction in patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD)

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) primarily manifests in neonates or infants with hepatomegaly, liver dysfunction, and hypoglycemia. This study investigated the functions of islet beta cells and their correlations with liver dysfunction in NICCD patients.We retrospectively analyzed clinical data on liver function and islet beta cell functions for 36 patients diagnosed with NICCD and 50 subjects as the control group. The NICCD group had significantly higher total bilirubin (TBIL), direct bilirubin (DBIL), alanine aminotransferase (ALT), aspartate amino transferase (AST), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP) and alpha-fetoprotein (AFP) levels and albumin/globulin ratio (A/G) (P < .05), and lower ALB and GLB levels than the control group (P < .05). The differences in fasting blood glucose (FBG), fasting insulin, C-peptide (C-P), the homeostasis model of assessment for the insulin resistance index (HOMA-IR), fasting beta cell function (FBCI), and the HOMA beta cell function index (HBCI) between the NICCD and control groups were not significant (P > .05). A linear correlation was found between FBG and fasting insulin (P < .001) and between FBG and C-P in the NICCD patients (P = .001). Fasting insulin (P = .023), HOMA-IR (P = .023), FBCI (P = .049), and HBCI (P = .048) were positively correlated with increases in the ALT level. There was no difference in islet beta cell functions between the NICCD and control groups. The liver dysfunction may be correlated with islet beta cell functions in NICCD patients.

Blood glucose and insulin and correlation of SLC25A13 mutations with biochemical changes in NICCD patients

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is a hereditary metabolic disease arising from biallelic mutations of SLC25A13. This study aimed to explore the characteristics of fasting blood glucose (FBG), fasting insulin (FINS) and C-peptide (C-P) levels in NICCD infants, analyze their SLC25A13 genetic mutations and further discuss the correlation between SLC25A13 genetic mutations and biochemical changes. Seventy-two cases of infants with cholestasis disease were gathered. Among them, 36 cases with NICCD diagnosis were case group. Meanwhile, 36 cases with unknown etiology but excluded NICCD were control group. FBG, FINS, C-P, ALT, AST, GGT, ALP, TG, HDL-C, LDL-C and Non-HDL-C were collected from all subjects, and DNA was extracted from venous blood for SLC25A13 mutations detection. The incidence of hypoglycemia was 3% in NICCD group. There were no significant statistical difference of FBG, FINS and C-P between NICCD and INC groups ( P > 0.05). ALT, LDL-C and Non-HDL-C levels in NICCD group were lower than the INC group, while SLC25A13 mutations were associated with the level of GGT ( P < 0.05). Ten different SLC25A13 genetic mutations were detected, among which, 851del4, IVS16ins3kb, IVS6+5 G > A and 1638ins23 mutations made up 82% of all mutations. The incidence of hypoglycemia may be higher in small gestational age infants with NICCD. Low LDL-C may be one of the characteristics of dyslipidemia in NICCD infants. There was a correlation between SLC25A13 gene mutations distribution and the GGT level, but the meaning of this finding remains to be further in-depth study. Impact statement This study aims to compare FBG, FINS, C-P, other biochemical and clinical manifestations between NICCD and non-NICCD infants, and discuss differential diagnosis of NICCD and INC beyond the genetic analysis. And investigate the correlation between SLC25A13 genetic mutations and biochemical changes. This work presented that incidence of hypoglycemia may be higher in small gestational age infants with NICCD. Low LDL-C may be one of the characteristics of dyslipidemia in NICCD infants. There was a correlation between SLC25A13 gene mutations distribution and the GGT level.

Adult liver disorders caused by inborn errors of metabolism: review and update

Inborn errors of metabolism (IEMs) are a group of genetic diseases that have protean clinical manifestations and can involve several organ systems. The age of onset is highly variable but IEMs afflict mostly the pediatric population. However, in the past decades, the advancement in management and new therapeutic approaches have led to the improvement in IEM patient care. As a result, many patients with IEMs are surviving into adulthood and developing their own set of complications. In addition, some IEMs will present in adulthood. It is important for internists to have the knowledge and be familiar with these conditions because it is predicted that more and more adult patients with IEMs will need continuity of care in the near future. The review will focus on Wilson disease, alpha-1 antitrypsin deficiency, citrin deficiency, and HFE-associated hemochromatosis which are typically found in the adult population. Clinical manifestations and pathophysiology, particularly those that relate to hepatic disease as well as diagnosis and management will be discussed in detail.

Inspissated bile syndrome in an infant with citrin deficiency and congenital anomalies of the biliary tract and esophagus: identification and pathogenicity analysis of a novel SLC25A13 mutation with incomplete penetrance

Biallelic mutations of the SLC25A13 gene result in citrin deficiency (CD) in humans. Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is the major CD phenotype in pediatrics; however, knowledge on its genotypic and phenotypic characteristics remains limited. The present study aimed to explore novel molecular and clinical characteristics of CD. An infant suspected to have NICCD as well as her parents were enrolled as the research subjects. SLC25A13 mutations were investigated using various methods, including cDNA cloning and sequencing. The pathogenicity of a novel mutation was analyzed bioinformatically and functionally with a yeast model. Both the infant and her father were heterozygous for c.2T>C and c.790G>A, while the mother was only a c.2T>C carrier. The novel c.790G>A mutation proved bioinformatically and functionally pathogenic. The infant had esophageal atresia and an accessory hepatic duct, along with bile plug formation confirmed by laparoscopic surgery. However, the father seemed to be healthy thus far. The findings of the present study enrich the genotypic and phenotypic characteristics of CD patients, and provided clinical and molecular evidence suggesting the possible non-penetrance of SLC25A13 mutations and the likely involvement of this gene in primitive foregut development during early embryonic life.