Patient 3 was a 1-year-and-2-month-old female referred to our hospital because of abnormal liver function discovered for 12.7 months. At the age 1.3 months, she went through a liver function test because of prolonged jaundice for 1 month, which showed raised levels of AST, GGT, ALP, TBIL, DBIL, and IBIL (). When aged 1.8 months, her TBA level was found to be as high as 172.0 µmol/L besides the cholestatic alterations (), and the MS-MS analysis revealed increased levels of tyrosine, citrulline, and methionine while large quantities of urinary 4HPPV and 4HPL were detected on GC-MS analysis. NICCD was consequently suspected, and breast-feeding was stopped while a lactose-free and MCT-enriched formula was suggested. Following that, her cholestatic jaundice got alleviated rapidly and the laboratory alterations recovered to normal levels by the age 5 months, while the hypercholanemia was intractable, even beyond 1 year of age ().\nAs the first child of a non-consanguineous couple, the infant was delivered by cesarean section at the gestation age of 38 weeks and 2 days with the birth weight 2,750 g. Her father was clinically healthy with an elevated serum TBA level of 21.1 µmol/L (0–10 µmol/L), and her mother was physically and biochemically healthy (). There was no family history of any genetic diseases.\nPhysical examination at referral revealed a body weight 10.1 kg, length 80 cm and head circumference 46 cm. No jaundice was observed in the skin and sclera. Examinations of the heart, the lungs, the abdomen, and nervous system were all normal.\nBiochemical test at referral revealed a TBA level 50.9 µmol/L with otherwise normal indices (). On genetic analysis, the patient was a compound heterozygote of the SLC25A13 mutations c.852_855del4 and c.1638_1660dup, which was inherited from the father and mother, respectively (); moreover, the patient and her father were both homozygous for the SLC10A1 variant c.800C > T (p.Ser267Phe), while her mother was a carrier (). Hence, citrin deficiency and NTCP deficiency were definitely diagnosed for the infant. No specific therapy was given, and his TBA level tended downward to 25.6 µmol/L at the age of 3 years and 4 months (), still remaining beyond the upper limit. The patient also had a fondness of protein-rich foods while an aversion to carbohydrate-rich foods from the age 1 year.\nThe molecular findings above were further confirmed by Sanger sequencing () and illustrated as family tree diagrams (). The clinical and molecular features of all the 3 patients were summarized in .
Patient 1. A 2-years-old female infant was referred to the First Affiliated Hospital, Jinan University, due to elevated serum total bile acids (TBA) discovered for 21 months. At the age 3 months, she was admitted to Women and Children's Hospital of Quanzhou because of jaundice for 2 months. Laboratory test revealed that the serum levels of TBA, direct bilirubin (DBIL), aspartate transaminase (AST) and alanine transaminase (ALT) were all elevated (Table ), and she was thus diagnosed to have cholestatic liver disease. After being treated with intravenous reduced glutathione and ademetionine-1,4-butanedisulfonate for 9 days, which were commonly used in cholestatic patients with elevated alanine transaminase levels, her jaundice was alleviated, but the liver function indices remained abnormal (Table ). Then oral ursodesoxycholic acid was given and she was discharged at the age 3.3 months. During the subsequent follow-up over 20 months, she showed normal anthropometric and neurobehavioral development without abnormal appearance, and her cholestasis resolved completely since the age 7 months. However, persistently raised TBA levels were observed on repeated biochemical analyses (Table ). So she was referred to our hospital for further investigation and management when aged 2 years.\nThe patient was the elder sister of two monochorionic diamniotic twins who was delivered by cesarean section at the gestation age of 37 weeks and 2 days with the birth weight 2.25 kg and body length 45.0 cm. Her father is a hepatitis B virus (HBV) carrier who was clinically healthy but with slightly elevated serum TBA level on biochemistry analysis, and her mother was physically and biochemically healthy (Table ). There was no family history of any genetic disease.\nPhysical examination revealed a body weight of 12.0 kg, height 83.5 cm and head circumference 46.0 cm. No jaundice was observed in the skin and sclera. No stridor, crackles or crepitus was heard in the two lungs, and the heart sound was normal without any murmurs. There was no abdominal distention, and the liver and spleen were non-palpable. Physiological reflexes were normal and no pathological reflexes could be found on nervous system examination. On biochemical analysis, the TBA level reached 173.8 μmol/L (0–10 μmol/L) as other indices were normal (Table ).