A 24-year-old woman presented at the First Affiliated Hospital of Xi’an Jiaotong University in September with jaundice for 24 years and liver cirrhosis for one year. She had been diagnosed with non-autoimmune hemolytic anemia 24 years ago, based on a medical history of persistent anemia and hyperbilirubinemia. Eight years later, she underwent splenectomy due to refractory anemia, severe jaundice, and splenomegaly. At 22 years of age, the jaundice reappeared with abdominal distension, liver discomfort, fatigue, anorexia, and fever. Laboratory tests showed a hemoglobin level of 110 g/L, platelet count of 198×109/L, reticulocyte ratio of 15%, aspartic transaminase level of 87.8 U/L, glutamic transaminase level of 71 U/L, total bilirubin level of 127 µmol/L, and albumin level of 29.6 g/L. Peripheral blood smear tests showed visible round and densely colored spherical red blood cells, which lacked pale white centers and presented smaller diameters than normal red blood cells. A hemoglobin peptide chain analysis revealed no abnormalities. Hemolysis reaction, red blood cell osmotic fragility test, and G6PD activity were normal. Both the father and younger brother suffered from hemolytic anemia, and 16 years ago, her younger brother underwent splenectomy due to hemolytic anemia (Fig. 1).
To identify genetic factors of the disease, the peripheral blood of the proband, the proband’s parents, and the proband’s younger brother were obtained. The 6297 genetic phenotypes currently confirmed by OMIM were tested through a whole exome NGS analysis that focused on a total of 412 genes related to the subject’s clinical phenotype. As a result, one heterozygous nonsense mutation, c.4117C > T,p.Q1373X (reference sequence: NM_001355436), was identified in exon 20 of the proband’s SPTB gene, the proband’s parents, and the proband’s younger brother (Fig. 2).
SPTB gene abnormalities lead to hereditary spherocytosis type 2 with autosomal dominant inheritance (OMIM#616649). In this test, we detected a nonsense variant in the SPTB gene of the proband that was inherited from her father, and the father and younger brother of the proband carried the same heterozygous variant. In autosomal dominant diseases, a single pathogenic variant can cause disease. The mutation was not found in public population sequence databases, including HGMD, 1000 Genomes Project Database, ESP6500, ExAC, and dbSNP. The mutation sequence was predicted in SWISS-MODEL, and it was found that the mutation of the β-spectrum protein p.Q1373X caused the early termination of the protein and subsequently triggered the loss of α-helix (Fig. 3). Based on clinical symptoms, laboratory tests, and NGS sequencing, the proband was diagnosed with HS.
The hepatitis virus antibody, autoantibody, and autoimmune liver disease antibody screening were all negative. Furthermore, Epstein-Barr virus DNA and cytomegalovirus DNA were both negative. Screening for metabolic disorders such as hemochromatosis and hepatolenticular degeneration were normal, and no long-term heavy drinking, nutritional disorders, or exposure to industrial poisons or drugs were noted. With regards to 16,569 sites in the patient's mitochondrial gene, no abnormalities were found in 66 mutations that have been reported to cause disease. Re-analysis of the data of all exons did not reveal a second single-gene disease.
Later, she experienced severe upper gastrointestinal bleeding accompanied by hepatic encephalopathy and massive ascites, and her hemoglobin level was at least 50 g/L. Laboratory tests showed an aspartic transaminase level of 65 U/L, glutamic transaminase level of 44 U/L, total bilirubin level of 213.3 µmol/L, albumin level of 33 g/L, plasma ammonia level of 97 µmol/L, creatinine level of 64 µmol/L, INR of 1.67, and So MELD score of 22. Gastroscopy showed esophageal varices (Lemi D 2 Rf1), and computed tomography of the abdomen revealed liver cirrhosis, portal hypertension, massive abdominal and pelvic effusion, thickening of the gallbladder wall, and bilateral pleural effusion. Liver computed tomography angiography images showed a thin hepatic artery, portal hypertension, opening of the left gastric vein, and varicose veins in the lower part of the esophagus and stomach, which presented multiple nodules in the liver, with low-density shadows in the right leaf of the liver. Liver magnetic resonance imaging showed multiple patchy abnormal enhancements in the liver during the dynamic phase, and some of the cirrhotic nodules could be malignant. A liver biopsy was not performed because of coagulopathy.
The patient underwent classic orthotopic liver transplantation and portal vein thrombectomy in October 2019. Histopathological examination of the resected specimens revealed nodular liver cirrhosis and chronic cholecystitis. The portal vein thrombosis pathology showed thrombosis with organization (Fig. 4). At the follow-up more than one year after liver transplantation, the patient showed good signs of recovery.