Citrin deficiency is an important etiology for cholestatic liver disease in children / 中华儿科杂志

<p><b>OBJECTIVE</b>To explore the major etiological features of cholestatic liver disease (CLD) in children, and to investigate the molecular epidemiological distribution of SLC25A13 mutations in CLD.</p><p><b>METHOD</b>A clinical cross-sectional investigation was performed on 63 CLD cases diagnosed from Oct. 2003 to Mar. 2009 in our department, including 36 males and 27 females. Their clinical data were collected, and etiology and prognosis were analyzed and summarized. Thirteen to 17 mutations in SLC25A13 gene were screened by means of procedures established previously by our group. Several SLC25AJ3 mutations were detected by direct sequencing of DNA fragments amplified by genomic DNA-PCR.</p><p><b>RESULT</b>No specific etiologies were identified in 24 of the 63 cases. Among the 39 cases with identified etiologies, inherited metabolic diseases were on top of the list, including 6 kinds and 27 cases in total, i.e., neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD, 21 cases), transient galactosemia, tyrosinemia type I, galactose kinase deficiency, ornithine carbamoyl transferase deficiency and glycogen storage disease type I, followed by acquired causes (7 cases in total), such as total parenteral nutrition associated cholestasis (TPNAC), congenital syphilis and CMV hepatitis; and then biliary tract malformation (5 cases in total), including biliary atresia, Caroli's disease and gallbladder polyp, were the third. Ten of the 55 patients on follow-up have passed away, while the remaining 45 cases were improved or recovered clinically. SLC25A13 gene analysis were performed in 44 CLD subjects and 21 of them from 20 families (with 40 SLC25A13 alleles in total) were found to have mutations, and the seven mutations detected were 851-854del (23/40), IVS6 + 5G > A (6/40), IVS16ins3kb (3/40), 1638-1660dup (2/30), A541D (1/30), R319X (1/30) and G333D (1/30), respectively, and there were other 3 mutations (3/40) still needing identification in the remaining 3 alleles.</p><p><b>CONCLUSION</b>The etiologies for CLD in some cases can not be identified. However, inherited metabolic diseases, including NICCD in particular, constitute common causative factors for CLD. Most of the CLD conditions can be improved, even recovered clinically, although some cases presented with poor prognosis. Seven mutations in SLC25A13 gene were detected, among which, 851-854del, IVS6 + 5G > A, IVS16ins3kb and 1638-1660dup were the leading four mutations, respectively.</p>

Failure to thrive and dyslipidemia caused by citrin deficiency: a novel clinical phenotype / 中国当代儿科杂志

Two clinical phenotypes for citrin deficiency (CD) have been reported. One is adult-onset citrullinemia type II (CTLN2) and another is neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). A child with CD and who had failure to thrive (FTT) and dyslipidemia as main clinical manifestations is reported here. Both the weight-and length-for-age at 18 months dropped below the 3rd percentile in the corresponding WHO anthropometry percentile charts, while blood biochemical analysis revealed dramatically increased triglyceride and total cholesterol, together with reduced HDL-cholesterol. Inquiries revealed his aversion to rice and fondness for fish since the age of one year, a peculiar habit which could not be corrected. Since the age of two years, the peculiar diet became more obvious, and slightly increased citrulline and threonine levels were detected on blood amino acid analysis. At the age of two years and five months he was suspected to have CD. Since then, he has been fed in accordance with his own food preferences, and FTT improved gradually, with weight-for-age, in particular, recovering beyond the 3rd percentile at three years of age, and dyslipidemia was also ameliorated gradually. SLC25A13 gene analysis revealed a homozygote of 851del4, and CD was thus confirmed. Diet survey at four years and seven months revealed a fondness for high-protein and low-carbohydrate foods, such as seafood, meat, eggs and milk. This child presented with FTT and dyslipidemia as main clinical manifestations and this was a novel CD phenotype different from NICCD and CTLN2.

Overview of Citrin Deficiency:SLC25A13 Mutations and the Frequency / 实用儿科临床杂志

Citrin deficiency, autosomal recessive disorder, caused by mutation of SLC25A13 gene on chromosome 7q21.3 has two major phenotypes : neonatal intrahepatic chnlestatic hepatitis(N1CCD) and adult-onset type Ⅱ citrullinemia(CTLN2).So far, we have identified 52 SLC25A13 mutations and diagnosed the patients not only in Japan(166 CTLN2 and 238 NICCD) but also in other countries.We have detected 76 Chinese, 13 Korean and 15 Vietnamese patients with the same mutations as Japanese, and 13 patients(from Israel, UK, USA or Czech)with mutations different from those found in Japanese,indicating a wide distribution of citrin deficiency.DNA diagnoses of 13 known SLG25A13 mutations revealed that the carrier frequency was high in East Asian populations:Chinese(73/4 600=1/63) ,Japanese(21/1372=1/65) and Korean(25/2 690=1/108), suggesting that near by 100 000 East Asians are liomozygotes.It is important to find out patients with citrin deficiency,to treat them,and to prevent onset of severe CTLN2.

Progresses and perspectives in the study on citrin deficiency / 中华医学遗传学杂志

Citrin deficiency causes autosomal recessive disorders including adult-onset type II citrullinemia (CTLN2) and neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD). The responsive gene of citrin deficiency, SLC25A13, locates on chromosome 7q21.3 and encodes citrin as a liver-type mitochondrial aspartate/glutamate carrier (AGC). The mutations on SLC25A13 will result in deficiency of citrin and CTLN2 or NICCD. Citrin deficiency was found at first in Japan. However, recently, some of cases were identified in China, Korea, Vietnam, Israel, Czech, United States and England, and racial differences of the SLC25A13 mutations were found, suggesting the patients with citrin deficiency maybe exist worldwide. In this article, authors reviewed the progresses in the study on citrin deficiency up to now and put forward authors' considerations for further research on it.

A difficult and complicated case study: neonatal intrahepatic cholestasis caused by citrin deficiency / 中国当代儿科杂志

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is a kind of inborn errors of metabolism, with the main clinic manifestations of jaundice, hepatomegaly, and abnormal liver function indices. As a mitochondrial solute carrier protein, citrin plays important roles in aerobic glycolysis, gluconeogenesis, urea cycle, and protein and nucleotide syntheses. Therefore citrin deficiency causes various and complicated metabolic disturbances, such as hypoglycemia, hyperlactic acidemia, hyperammonemia, hypoproteinemia, hyperlipidemia, and galactosemia. This paper reported a case of NICCD confirmed by mutation analysis of SLC25A13, the gene encoding citrin. The baby (male, 6 months old) was referred to the First Affiliated Hospital with the complaint of jaundice of the skin and sclera, which it had suffered from for nearly 6 months. Physical examination showed obvious jaundice and a palpable liver 5 cm below the right subcostal margin. Liver function tests revealed elevated enzymatic activities, like GGT, ALP, AST, and ALT, together with increased levels of TBA, bilirubin (especially conjugated bilirubin), and decreased levels of total protein/albumin and fibrinogen. Blood levels of ammonia, lactate, cholesterol, and triglyceride were also increased, and in particular, the serum AFP level reached 319,225.70 microg/L, a extremely elevated value that has rarely been found in practice before. Tandem mass analysis of a dried blood sample revealed increased levels of free fatty acids and tyrosine, methionine, citrulline, and threonine as well. UP-GC-MS analysis of the urine sample showed elevated galactose and galactitol. The baby was thus diagnosed with suspected NICCD based on the findings. It was then treated with oral arginine and multiple vitamins (including fat-soluble vitamins A, D, E, and K), and was fed with lactose-free and medium-chain fatty acids enriched formula instead of breast feeding. After half a month of treatment, the jaundice disappeared, and the laboratory findings, including liver function indices, blood levels of ammonia, lactate and AFP, were returned to normal level. The baby was followed up for 6 months. It developed well, and the abnormal laboratory findings, including MS-MS and UP-GC-MS analysis results, have been corrected, except a slightly elevated lactate level sometimes. SLC25A13 gene mutation analysis for the patient revealed a compound heterozygote of mutation 851del4 and 1638ins23 and therefore NICCD was definitely diagnosed.