Patient 2 was a 1-year-and-1-month-old male visiting our clinic due to hypercholanemia discovered for 11 months. At the age 2 months, he was referred to a local hospital because of prolonged jaundice for about 1 month. On biochemistry analysis, elevated serum levels of AST, GGT, ALP, TBIL, DBIL, and IBIL, together with decreased level of albumin were detected, and notably, the TBA level reached 268.7 micromol/L ( Table 2 ). Subsequent urinary GC-MS analysis detected elevated 4-hydroxyphenylpyruvate (4-HPPV) and 4HPL, while raised levels of citrulline, methionine, and threonine were detected on MS-MS analysis of blood sample. When aged 2.1 months, the infant undertook SLC25A13 analysis in our hospital, and proved to be a homozygote of the c.852_855del4 mutation ( Figure 1B ), and the diagnosis of NICCD was thus made. Then breast-feeding was stopped and a lactose-free and MCT-enriched formula was given. Then his jaundice disappeared rapidly, and serum bilirubin levels returned to normal at his age 5.5 months ( Table 2 ). However, the hypercholanemia persisted, even beyond 1 year of age ( Table 2 ). No steatorrhea or acholic stool was observed during the course of the disease.
As the first child of a non-consanguineous couple, the patient was delivered vaginally at the gestational age of 37 weeks and 4 days with the birth weight 2700 g. The Apgar score was 9 points at 1 min and 10 points at 5 min after umbilical ligation. Parents were both hepatitis B virus (HBV) carriers, who were apparently healthy but with slightly raised serum TBA levels ( Table 2 ). Family history of any genetic diseases was denied.
Physical examination revealed a body T 36.6 C, weight 10.5 kg, HR 126 bpm, and RR 32 bpm. No jaundiced skin and sclera was observed. On auscultation, no abnormal sounds were heard on the lungs and heart. There was no abdominal distention, and the liver and spleen were non-palpable. Primitive reflexes were normal and pathological reflexes could not be found on nervous system examination.
Laboratory test at visiting revealed a serum TBA level of 234.5 micromol/L and otherwise normal indices. SLC10A1 genetic analysis demonstrated that the patient was a homozygote, and his parents, carriers, of the variant c.800C > T (p.Ser267Phe) ( Figure 1F ). The diagnosis of NTCP deficiency was thus made. No specific therapy was given but clinic follow up was suggested. His serum TBA level was 148 micromol/L ( Table 2 ) when aged 1 year and 6 months, and a fondness for low-carbohydrate and high-protein foods was noticed since the age of 1 year.