A three-month-old boy was admitted to our hospital because of a history of jaundice and intractable diarrhea after birth. The boy was born full-term by cesarean section with a birth weight of 2,250 g. He is the second child of a healthy non-consanguineous couple of Chinese Han ethnicity. The family history was unremarkable. His five-year old brother was healthy. Mild jaundice of the skin and the sclera were observed after birth, and diarrhea was characterized by loose, yellow-green, non-bloody stools occurring 3-5 times per day. He was diagnosed with neonatal jaundice and was discharged from the neonatology department after improvement in the serum bilirubin level. However, jaundice and diarrhea persisted, and he was admitted to the local hospital again when he was 3 months old. Laboratory tests showed highly elevated levels of total serum bilirubin (TB 137.8 mumol/L, reference range: 3.4-17.1 mumol/L), direct bilirubin (DB 107.8 mumol/L, reference range: 0-6.8 mumol/L), and total bile acid (TBA 217.3 mumol/L, reference range: 0-10 mumol/L), and then he was transferred to our hospital for further evaluation.
On admission, the patient's body temperature was 36.8 C, heart rate was 137 per min, respiratory rate was 27 per min, and blood pressure was 88/57 mmHg. He had a normal weight of 4.8 kg and a height of 58 cm. The skin of the face, trunk, and limbs and the sclera were mildly yellow. The heart and lungs were normal, the abdomen was soft, the liver was 4 cm below the ribs, and the spleen was not touched under the ribs. The muscle strength and tension of the limbs and the neurological examination were unremarkable. The binaural auditory brainstem response (ABR) wave V threshold was 25 dBHL. The liver biochemical profile revealed elevated levels of alanine aminotransferase (ALT 391 U/L, reference range: 5-40 U/L), aspartate aminotransferase (AST 565 U/L, reference range: 8-40 U/L), gamma-glutamyltransferase (GGT 81 U/L, reference range: 7-32 U/L), TB 136.7 mumol/L (reference range: 3.4-17.1 mumol/L), DB 104.4 mumol/L (reference range: 0-6.8 mumol/L), and TBA 195 mumol/L (reference range: 0-10 mumol/L) (Table 1). The detection of liver-damaging pathogens was negative, including Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), and hepatitis A, B, and C viruses. Abdominal ultrasound indicated hepatomegaly with diffuse changes. Hepatobiliary scintigraphy with single-photon emission computed tomography (SPECT) revealed impaired hepatic uptake and clearance function and delayed biliary excretion. Magnetic resonance imaging (MRI) showed that the gallbladder was filled, and the common bile duct was less visible. BA was excluded by laparoscopic common bile duct exploration. The diagnosis of intrahepatic cholestasis was made, and the patient was treated with symptomatic therapies of oral ursodeoxycholic acid (UDCA, 50 mg/day), fat-soluble vitamins (vitamin AD, 1800 U/day; vitamin E, 25 mg/day), intravenous compound glycyrrhizin (15 mg/day), and ademetionine 1, 4-butanedisulfonate (250 mg/day).
To further investigate the etiology of intrahepatic cholestasis, exome sequencing (ES) using genomic DNA extracted from peripheral blood was performed on a HiSeqX10 (Illumina, United States) platform. Novel compound heterozygote variants c.292C>T (p.Arg98Trp)/c.2534-2545del (p.Leu845-Met848del) in UNC45A were identified and were further confirmed by Sanger sequencing (Figure 1). No other potentially pathogenic variants were observed in known genes related to cholestasis. Genotyping of the unaffected family members by Sanger sequencing showed that his mother carries the c.292C>T (p.Arg98Trp) variant, his father carries the c.2534-2545del (p.Leu845-Met848del) variant, and both variants are not detected in his brother (Figure 1). Variant c.292C>T (p.Arg98Trp) is found four times (4/282,568) in heterozygotes, and c.2534-2545del (p.Leu845-Met848del) is reported only once (1/250,666) in the heterozygote state in the gnomAD database. In silico tools predicted that the c.292C>T (p.Arg98Trp) missense variant is deleterious (PROVEAN score, -6.989; PolyPhen-2 score, 1.000). The c.2534-2545del (p.Leu845-Met848del) variant leads to a deletion of four amino acids in the C-terminal UCS domain, and it is predicted to be deleterious with a PROVEAN score of -16.547.