1.Identification and diagnosis of three novel mutations in SLC25A13 gene of neonatal intrahepatic cholestasis caused by citrin deficiency
Yuan-Zong SONG ; Jian-Sheng SHENG ; USHKAI MIHARU ; HWU WUH-LIANG ; Chun-Hua ZHANG ; KOBAYASHI KEIKO
Chinese Journal of Pediatrics 2008;46(z1):40-44
Objective Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD, OMIM 605814 ) is a novel autosomal recessive disease results from mutations in the gene SLC25A13 that encodes for citrin, a liver-type aspartate/glutamate cartier located in the mitochondrial inner membrane. Most of the Chinese NICCD patients diagnosed by genetic analysis had the sameSLC25A13 mutations as Japanese, however, in some cases, the known mutations were not detected. This research aimed to identify novel SLC25A13 mutations in Chinese NICCD patients and to explore the experimental conditions for their genetic diagnosis.Methods Genomic DNA was extracted from blood samples of 3 NICCD patients from Taiwan (P757), Guangdong (P1194) and Hebei (P1443) Province of China, respectively; and all the 18 exons and their flanking sequences of SLC25A13 gene were sequenced. Furthermore, the identified novel mutations were diagnosed by amplification with PCR, digestion with corresponding restriction endonuclease, and agarose gel electrophoresis.Results Three novel mutations identified in SLC25A13 gene of the 3 NICCD patients were an abnormal splicing IVS7-2A>G (P757), a missense A541D (c. 1622C > A, P1194) and a nonsense R319X (c. 955C > T, P1443). The PCR-RFLP procedures for their genetic diagnosis were also established, with specific fragments on electrophoresis after digestion of the PCR products with three different restriction endonucleases Msp Ⅰ, Hpy188Ⅰ and Taq Ⅰ, respectively.Conclusions The three novel mutations in SLC25A13 gene of Chinese NICCD patients were first identified, suggesting that SLC25A13 mutation distributed in Chinese population is somewhat different from that in Japanese. Moreover, the PCR-RFLP diagnostic procedures established in this research provide valuable tools not only for the genetic diagnosis of NICCD but also for further molecular epidemiologic investigations in Chinese population.Acknowledgement We are grateful to all research subjects and their family members for their cooperation, and to many members of medical staff who contributed much to this research. This study was financially supported partially by Guangdong Provincial Research Grant for Science and Technology (No. 2004B50301008) and the Major State Basic Research Development Program of China (No. 2007CB511901 ), and by Grants-in-Aid for Scientific Research (B: Nos. 16390100 & 19390096 ) and for Asia-Africa Scientific Platform Program (AASPP) from the Japan Society for the Promotion of Science.