Two different pathogenic gene mutations coexisted in the same hereditary spherocytosis family manifested with heterogeneous phenotypes

Abstract

Background: Hereditary spherocytosis (HS) is a common type of hereditary hemolytic anemia. According to the current diagnostic criteria of HS, patients with a family history of HS, typical clinical features and laboratory investigations could be diagnosed without the requirement of any additional tests, including genetic analysis. However, the clinical heterogeneities incur difficulties in HS diagnosis. We therefore aimed to investigate the application of genetic diagnosis in a family-based cohort. Case presentation: In the present Chinese family, two probands sharing similar clinical manifestations, including jaundice, cholelithiasis, splenomegaly and spherocytes, while the clinical features of other family members were inconclusive. Whole-exome sequencing (WES) unexpectedly unveiled two separate disease-causing mutations in the two probands. SPTB R1625X mutation detected in proband D was a de novo mutation; while proband W inherited the SLC4A1 c.G1469A mutation from her mother, which was also inherited by her brother. However, the clinical features of proband W and her mother and brother were discrepant: proband W suffered from significant splenomegaly, jaundice and cholelithiasis, which resulted in cholecystectomy and splenectomy; while her mother and brother's HS were not complicated by cholelithiasis, and their splenomegaly and elevated serum bilirubin were moderate. In addition, additional genomic defects involved with HS-related symptoms have not been detected in this family. Conclusions: Both genotypes and phenotypes could be heterogeneous in the same HS family. The analysis of pathogenic gene mutations may endeavor to play an indispensable role in the accurate diagnosis and genetic consultation of HS individuals and their family members.