Analysis of daily energy, protein, fat, and carbohydrate intake in citrin-deficient patients: Towards prevention of adult-onset type II citrullinemia.

Patients with citrin deficiency during the adaptation/compensation period exhibit diverse clinical features and have characteristic diet of high protein, high fat, and low carbohydrate. Japanese cuisine typically contains high carbohydrate but evaluation of diet of citrin-deficient patients in 2008 showed a low energy intake and a protein:fat:carbohydrate (PFC) ratio of 19:44:37, which indicates low carbohydrate consumption rate. These findings prompted the need for diet intervention to prevent the adult onset of type II citrullinemia (CTLN2). Since the publication of the report about 10 years ago, patients are generally advised to eat what they wish under active dietary consultation and intervention. In this study, citrin-deficient patients and control subjects living in the same household provided answers to a questionnaire, filled-up a maximum 6-day food diary, and supplied physical data and information on medications if any. To study the effects of the current diet, the survey collected data from 62 patients and 45 controls comparing daily intakes of energy, protein, fat, and carbohydrate. Food analysis showed that patient's energy intake was 115% compared to the Japanese standard. The confidence interval of the PFC ratio of patients was 20-22:47-51:28-32, indicating higher protein, higher fat and lower carbohydrate relative to previous reports. The mean PFC ratio of female patients (22:53:25) was significantly different from that of male patients (20:46:34), which may explain the lower frequency of CTLN2 in females. Comparison of the present data to those published 10 years ago, energy, protein, and fat intakes were significantly higher but the amount of carbohydrate consumption remained the same. Regardless of age, most patients (except for adolescents) consumed 100-200 g/day of carbohydrates, which met the estimated average requirement of 100 g/day for healthy individuals. Finally, patients were generally not overweight and some CTLN2 patients were underweight although their energy intake was higher compared with the control subjects. We speculate that high-energy of a low carbohydrate diet under dietary intervention may help citrin-deficient patients attain normal growth and prevent the onset of CTLN2.

Current treatment for citrin deficiency during NICCD and adaptation/compensation stages: Strategy to prevent CTLN2.

Identification of the genes responsible for adult-onset type II citrullinemia (CTLN2) and citrin protein function have enhanced our understanding of citrin deficiency. Citrin deficiency is characterized by 1) neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD); 2) adaptation/compensation stage with unique food preference from childhood to adulthood; and 3) CTLN2. The treatment of NICCD aims to prevent the progression of cholestasis, and it includes medium chain triglycerides (MCT) milk and lactose-free milk, in addition to medications (e.g., vitamin K2, lipid-soluble vitamins and ursodeoxycholic acid). Spontaneous remission around the age of one is common in NICCD, though prolonged cholestasis can lead to irreversible liver failure and may require liver transplantation. The adaptation/compensation stage (after one year of age) is characterized by the various signs and symptoms such as hypoglycemia, fatty liver, easy fatigability, weight loss, and neuropsychiatric symptoms. Some poorly-controlled patients show failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD). Diet therapy is the key in the adaptation/compensation stage. Protein- and fat-rich diet with a protein: fat: carbohydrate ratio being 15-25%: 40-50%: 30-40% along with the appropriate energy intake is recommended. The use of MCT oil and sodium pyruvate is also effective. The toxicity of carbohydrate is well known in the progression to CTLN2 if the consumption is over a long term or intense. Alcohol can also trigger CTLN2. Continuous intravenous hyperalimentation with high glucose concentration needs to be avoided. Administration of Glyceol® (an osmotic agent containing glycerol and fructose) is contraindicated. Because the intense treatment such as liver transplantation may become necessary to cure CTLN2, the effective preventative treatment during the adaptation/compensation stage is very important. At present, there is no report of a case with patients reported having the onset of CTLN2 who are on the diet therapy and under the appropriate medical support during the adaptation/compensation stage.

Medium-chain triglycerides supplement therapy with a low-carbohydrate formula can supply energy and enhance ammonia detoxification in the hepatocytes of patients with adult-onset type II citrullinemia.

Citrin, encoded by SLC25A13, constitutes the malate-aspartate shuttle, the main NADH-shuttle in the liver. Citrin deficiency causes neonatal intrahepatic cholestasis (NICCD) and adult-onset type II citrullinemia (CTLN2). Citrin deficiency is predicted to impair hepatic glycolysis and de novo lipogenesis, resulting in hepatic energy deficit. Secondary decrease in hepatic argininosuccinate synthetase (ASS1) expression has been considered a cause of hyperammonemia in CTLN2. We previously reported that medium-chain triglyceride (MCT) supplement therapy with a low-carbohydrate formula was effective in CTLN2 to prevent a relapse of hyperammonemic encephalopathy. We present the therapy for six CTLN2 patients. All the patients' general condition steadily improved and five patients with hyperammonemic encephalopathy recovered from unconsciousness in a few days. Before the treatment, plasma glutamine levels did not increase over the normal range and rather decreased to lower than the normal range in some patients. The treatment promptly decreased the blood ammonia level, which was accompanied by a decrease in plasma citrulline levels and an increase in plasma glutamine levels. These findings indicated that hyperammonemia was not only caused by the impairment of ureagenesis at ASS1 step, but was also associated with an impairment of glutamine synthetase (GS) ammonia-detoxification system in the hepatocytes. There was no decrease in the GS expressing hepatocytes. MCT supplement with a low-carbohydrate formula can supply the energy and/or substrates for ASS1 and GS, and enhance ammonia detoxification in hepatocytes. Histological improvement in the hepatic steatosis and ASS1-expression was also observed in a patient after long-term treatment.

First Bulgarian case of citrin deficiency caused by one novel and one recurrent mutation in the SLC25A13 gene.

Citrin deficiency is an autosomal recessive disorder caused by mutations in the SLC25A13 gene and has three phenotypes: neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) in newborns, failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD) in older children, and recurrent hyperammonemia with neuropsychiatric symptoms in citrullinemia type II (CTLN2) in adults. NICCD presents in the first few weeks of life with cholestatic hepatitis syndrome, multiple aminoacidemia and hypergalactosemia. To date almost all reported patients were from East Asia and only few cases from Caucasian origin have been described. We report the first Bulgarian case of NICCD. Mutation screening of the SLC25A13 gene revealed the compound heterozygous mutations c.1081C>T (p.R361*) and c.74C>A (p. A25E) which confirmed the diagnosis of NICCD. The nonsense mutation c.1081C>T (p.R361*) is novel.

Dietary management of urea cycle disorders: European practice.

BACKGROUND: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries. METHODS: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets. RESULTS: Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements. CONCLUSIONS: Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Effects of supplementation on food intake, body weight and hepatic metabolites in the citrin/mitochondrial glycerol-3-phosphate dehydrogenase double-knockout mouse model of human citrin deficiency.

The C57BL/6:Slc23a13(-/-);Gpd2(-/-) double-knockout (a.k.a., citrin/mitochondrial glycerol 3-phosphate dehydrogenase double knockout or Ctrn/mGPD-KO) mouse displays phenotypic attributes of both neonatal intrahepatic cholestasis (NICCD) and adult-onset type II citrullinemia (CTLN2), making it a suitable model of human citrin deficiency. In the present study, we show that when mature Ctrn/mGPD-KO mice are switched from a standard chow diet (CE-2) to a purified maintenance diet (AIN-93M), this resulted in a significant loss of body weight as a result of reduced food intake compared to littermate mGPD-KO mice. However, supplementation of the purified maintenance diet with additional protein (from 14% to 22%; and concomitant reduction or corn starch), or with specific supplementation with alanine, sodium glutamate, sodium pyruvate or medium-chain triglycerides (MCT), led to increased food intake and body weight gain near or back to that on chow diet. No such effect was observed when supplementing the diet with other sources of fat that contain long-chain fatty acids. Furthermore, when these supplements were added to a sucrose solution administered enterally to the mice, which has been shown previously to lead to elevated blood ammonia as well as altered hepatic metabolite levels in Ctrn/mGPP-KO mice, this led to metabolic correction. The elevated hepatic glycerol 3-phosphate and citrulline levels after sucrose administration were suppressed by the administration of sodium pyruvate, alanine, sodium glutamate and MCT, although the effect of MCT was relatively small. Low hepatic citrate and increased lysine levels were only found to be corrected by sodium pyruvate, while alanine and sodium glutamate both corrected hepatic glutamate and aspartate levels. Overall, these results suggest that dietary factors including increased protein content, supplementation of specific amino acids like alanine and sodium glutamate, as well as sodium pyruvate and MCT all show beneficial effects on citrin deficiency by increasing the carbohydrate tolerance of Ctrn/mGPD-KO mice, as observed through increased food intake and maintenance of body weight.

Recurrent liver failure in a 25-year-old female.

Acute liver failure (ALF) is defined as severe and sudden liver dysfunction leading to coagulopathy and encephalopathy in a previously healthy person without preexisting liver disease. Almost half of adult cases of ALF are due to acetaminophen toxicity, with 21% labeled indeterminate or other. We present a patient with a second episode of ALF, both episodes being initiated by catabolic stress. Elevated aminotransferases, jaundice, an elevated international normalized ratio, and confusion were typical of idiopathic ALF, and a low serum ceruloplasmin level initially led to a misdiagnosis of acute Wilson disease. Citrullinemia type I, a urea cycle defect caused by a deficiency of argininosuccinate synthetase, was diagnosed on the basis of plasma amino acids and was confirmed by molecular testing. Urea cycle defects are not generally considered causes of ALF in adults and are described rarely in children beyond the neonatal period. Our case illustrates the importance of screening patients with idiopathic ALF for a metabolic disorder. A prompt diagnosis and timely treatment enabled her to recover fully without the need for liver transplantation.

Chronic pancreatitis and pancreatic pseudocyst with adult-onset type II citrullinemia.

Citrin deficiency, which is caused by a mutation of SCL25A13, can manifest in older children as failure to thrive and dyslipidemia caused by citrin deficiency (FTTDCD) and in adults as recurrent hyperammonemia with neuropsychiatric symptoms in adult-onset type II citrullinemia (CTLN2). FTTDCD and CTLN2 are known to complicate hypertriglyceridemia and chronic pancreatitis. Here we report, for the first time, the case of a patient with chronic pancreatitis and pancreatic pseudocyst with CTLN2 who was treated using endoscopic ultrasound-guided cyst drainage (EUS-CD). A 33-year-old woman with down syndrome presented to our hospital with complaints of fever, abdominal distention, and biliary vomiting for the previous 2 weeks. Owing to her difficulties in communication, although she had been taking a nutritionally balanced diet regardless of her preference, chronic pancreatitis and pancreatic stones had already been observed at the time of CTLN2 diagnosis at the age of 30 years. Three years later, a merged pancreatic pseudocyst was detected, and EUS-CD was successfully performed. A high-fat diet therapy for FTTDCD and CTLN2 may have caused the development of the pancreatic pseudocyst combined with chronic pancreatitis in this case. Pancreatic pseudocysts associated with FTTDCD or CTLN2 can be treated in a similar manner to those resulting from other causes.

Dietary Management, Clinical Status and Outcome of Patients with Citrin Deficiency in the UK.

BACKGROUND: Little is known about the optimal dietary treatment for citrin deficiency. Our aim is to describe the management of UK citrin deficiency patients. METHODS: A longitudinal retrospective review was performed. Data were collected from medical records on presenting signs and symptoms, dietary management and clinical outcome. RESULTS: data were collected on 32 patients from 21 families. 50% were females (16/32). Median age at diagnosis was 4 y (5 days-35 y) with 12 patients diagnosed in the neonatal period with neonatal intrahepatic cholestasis (NICCD), eight later in childhood (FTTDCD) and 12 by family screening based on index cases from five families. No patient had adult-onset type II citrullinemia. The patient age at the time of data collection was a median of 11 y (1-44 y). 91% (29/32) of patients had normal physical and neurological development, 47% (15/32) experienced recurrent unexplained abdominal pain and 9% (3/32) episodes of hypoglycaemia. Siblings had different phenotypes (5 families had > 1 affected patient). Most patients preferred high protein foods, limiting sugar-containing foods. Only 41% (13/32) were prescribed a low CHO, high protein, high fat diet (restriction varied) and two used medium chain triglyceride (MCT) supplements. No patient was prescribed drug therapy. Twenty-five per cent (8/32) of patients were underweight and 41% (13/32) had height <-1 z-scores. CONCLUSIONS: patients presented with various phenotypes, symptoms and suboptimal growth. Symptoms and biochemical markers improved with age, but height remained low in some. More research is necessary to assess the effectiveness of dietary approaches in improving clinical outcomes and symptoms in citrin deficiency.

The Lack of Hepatocyte Steatosis in Adult-onset Type II Citrullinemia Patients as Assessed by 7-year Interval Paired Biopsies.

Adult-onset type II citrullinemia (CTLN2) is a urea cycle disease characterized by neurological and psychiatric abnormalities associated with hyperammonemia. One of the pathological features of CTLN2 is the presence of hepatocyte steatosis. The condition progresses in almost all CTLN2 patients to nonalcoholic fatty liver disease (NAFLD). We herein report a 74-year-old woman who developed CTLN2 without hepatocyte steatosis. The diagnosis was based on clinical and laboratory findings and confirmed by two liver biopsies conducted within 7 years, as well as by a DNA analysis, which demonstrated mutations in the SLC25A13 gene. We describe a rare CTLN2 case without hepatocyte steatosis in an elderly woman who responded well to a low-carbohydrate diet.

Nutritional management of urea cycle disorders.

Nutritional management of patients who have urea cycle disorders is one of the most challenging tasks in clinical nutrition. The degree to which protein intake should be restricted in urea cycle disorders requires complex calculations which depend on many variables such as specific enzyme defect, age-related growth rate, current health status, level of physical activity, amount of free amino acids administered, energy intake, residual urea cycle function, family lifestyle, use of nitrogen-scavenging medications, and the patient's eating behaviors. This paper presents two case histories and a series of recommendations outlining the nutrition management of urea cycle disorders. It also identifies difficulties that arise in the course of treatment, and suggests practical solutions for overcoming them.

Citrin deficiency presenting as acute liver failure in an eight-month-old infant.

Citrin deficiency typically presents as neonatal intrahepatic cholestasis and resolves in late infancy. Here we report a case of citrin deficiency that presented as acute liver failure in late infancy in an apparently healthy child. The full-term male infant weighed 3400 g at birth, and exhibited normal development for eight months, at which time he contracted bronchial pneumonia. The infant developed jaundice and laboratory tests indicated elevated bilirubin and ammonia levels and an abnormal coagulation profile. Plasma amino acid analysis showed elevated levels of tyrosine, methionine, citrulline, and arginine. Citrin deficiency was suspected, and genomic DNA analysis revealed a mutation (IVS16ins3kb) in SLC25A13, which encodes a mitochondrial aspartate-glutamate carrier protein. The infant was immediately put on a lactose-free, medium-chain-triglyceride-enriched formula with ursodeoxycholic acid and lipid-soluble vitamins. However, cholestasis and abnormal laboratory indices persisted, and the infant died at the age of 11.5 mo, two days before a scheduled liver transplantation. This case demonstrates that citrin deficiency can present in late infancy as acute liver failure triggered by infection, and may require liver transplantation.

Serial diffusion-weighted magnetic resonance imaging in adult-onset citrullinaemia.

A 25-year-old Chinese man presented with a 2-year history of recurrent coma. His plasma ammonia level was extremely elevated, with raised citrulline level and absence of argininosuccinic acid. Adult-onset citrullinaemia, a condition rarely reported outside the Japanese population, was diagnosed. Serial magnetic resonance (MR) imaging, including diffusion-weighted (DW) studies, showed initial involvement of the insula cortex and cingulate gyrus, changing to a pattern of multiple small lesions in the depths of the cortical sulci. This changing pattern of lesions over time on DW MR imaging has not previously been described in adult-onset citrullinaemia.

Multiple ovarian antral follicles in a preterm infant with neonatal intrahepatic cholestasis caused by citrin deficiency: a clinical, genetic and transcriptional analysis.

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is an autosomal recessive disease caused by the dysfunction of citrin, an aspartate/glutamate carrier encoded by the SLC25A13 gene. Considerable progress has been made on the diagnosis and treatment of NICCD, but its clinical and molecular features still remain far from being completely elucidated and generally understood. The infant, a preterm female delivered at a gestational age of 31 weeks, was referred to our hospital at the age of 8 months because of jaundice lasting for 4.5 months and ovarian masses uncovered for 3 months. Besides serum indices indicating cholestasis, elevated serum levels of luteinizing hormone, follicle stimulating hormone and estradiol were also detected. Abdominal magnetic resonance imaging demonstrated bilateral multi-cystic ovarian masses, with the largest size being 7.4 × 6.2 × 9.6 mm(3). SLC25A13 gene analysis revealed that the patient was a compound heterozygote of c.1177+1G>A and c.754G>A. The paternally-inherited mutation c.754G>A was a novel one with a carrier rate of less than 1%. SLC25A13 transcriptional study in peripheral blood lymphocytes (PBLs) documented a novel splice variant r.616_848del which resulted from c.754G>A, with another variant r.1019_1177del from the maternally-inherited c.1177+1G>A mutation. The diagnoses were NICCD and multiple ovarian antral follicles (minipuberty), and the patient responded well to a galactose-free and medium chain triglyceride (MCT)-enriched formula. The findings in this paper expanded the clinical and molecular spectrum of the SLC25A13 gene, and lent support to the concept that PBLs could be taken as a feasible specimen source for SLC25A13 transcriptional analysis.

A novel inborn error of metabolism detected by elevated methionine and/or galactose in newborn screening: neonatal intrahepatic cholestasis caused by citrin deficiency.

UNLABELLED: Adult-onset type II citrullinaemia, caused by deficiency of the citrin protein encoded by the SLC25A13 gene, is characterised by a liver-specific argininosuccinate synthetase deficiency. DNA analysis for citrin deficiency revealed that SLC25A13 mutations are the cause of a particular type of neonatal intrahepatic cholestasis. We retrospectively investigated nine infants with cholestatic jaundice of unknown origin, detected by newborn screening over a period of 17 years, to determine the role of SLC25A13 defects in children. The results of the newborn screening were varied; four neonates were positive for hypermethioninaemia, two for hyperphenylalaninaemia, one for hypergalactosaemia and two for both hypermethioninaemia and hypergalactosaemia. Clinical characteristics of the patients were severe intrahepatic cholestasis, hypercitrullinaemia, and fatty liver. The symptoms resolved in all patients by 12 months of age without special treatment other than nutritional management. Although five patients were lost to follow-up, we detected SLC25A13 mutations in the remaining four patients examined. CONCLUSION: the differential diagnosis of cholestatic jaundice of unknown origin in infants should therefore include citrin deficiency. In this paper, we stress the importance of newborn screening to detect infants with neonatal intrahepatic cholestasis caused by citrin deficiency.