Homo sapiens Raw sequence reads

This report presents a 16-year-old female with skin petechiae, thrombocytopenia, and splenomegaly. Imaging confirmed cavernous transformation of the portal vein, and bone marrow aspiration showed hemophagocytosis. Whole-exome sequencing identified compound heterozygous variants in IFIH1 (c.464C>A, p.Ala155Glu) and THSD1 (c.1279A>G, p.Ile427Val), inherited from her mother and father, respectively. This is the first documented case linking bigenic IFIH1 and THSD1 variants to cavernous transformation of the portal vein with an HLH-like phenotype. The findings suggest a synergistic pathogenic mechanism and underscore the value of genetic testing and pedigree analysis in diagnosing and counseling for rare diseases.