Identification of a novel splice variant in SEC23B gene in a patient with concomitant presence of congenital dyserythropoietic anemia II and Gilbert's syndrome

초록

Background: Congenital dyserythropoietic anemia II (CDA II) is a rare inherited disorder of defective erythropoiesis caused by SEC23B gene mutation. CDA II is often misdiagnosed as a more common type of clinically related anemia, or it remains undiagnosed due to phenotypic variability caused by the coexistence of inherited liver diseases, including Gilbert's syndrome (GS) and hereditary hemochromatosis. Methods: We describe the case of a boy with genetically undetermined severe hemolytic anemia, hepatosplenomegaly, and gallstones whose diagnosis was achieved by targeted next generation sequencing. Results: Molecular analysis revealed a maternally inherited novel intronic variant and a paternally inherited missense variant, c.[994-3C > T];[1831C > T] in the SEC23B gene, confirming diagnosis of CDA II. cDNA analysis verified that the splice acceptor site variant results in two mutant transcripts, one with an exon 9 skip and one in which exons 9 and 10 are deleted. SEC23B mRNA levels in the patient were lower than those in healthy controls. The patient was also homozygous for the UGT1A1*6 allele, consistent with GS. Conclusion: Identification of the novel splice variant in this study further expands the spectrum of known SEC23B gene mutations. Molecular genetic approaches can lead to accurate diagnosis and management of CDA II patients, particularly for those with GS coexisting.

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