Pseudo-dominant Wilson disease with an unresolved third-generation ATP7B finding

Wilson disease is an autosomal recessive copper metabolism disorder caused by pathogenic variants in the adenosine triphosphatase (ATPase) copper transporting beta gene (ATP7B ). We describe a Han Chinese family from Inner Mongolia with genetically confirmed pseudo-dominant Wilson disease in two consecutive generations and an unresolved diagnosis in a third-generation relative. Whole-exome sequencing and Sanger segregation analysis showed that the proband carried c.2621C>T (p.Ala874Val) and c.2333G>T (p.Arg778Leu) in trans. Her son and daughter carried c.2621C>T (p.Ala874Val) and c.2975C>T (p.Pro992Leu); their trans configuration and paternal origin of p.Pro992Leu were inferred from the pedigree because the deceased father was unavailable for testing. The 22-year-old grandson had a previous clinical diagnosis but only monoallelic c.2621C>T, negative Kayser-Fleischer rings, and no second ATP7B variant detected by whole-exome sequencing. This family highlights the need for careful phase assignment, spouse and offspring screening, and cautious reconciliation of clinical and molecular diagnoses.