Novel compound heterozygous mutation of the KNG1 gene associated with severe HMWK deficiency in a Chinese pedigree

We report a novel compound heterozygous mutation (c.611C>T and c.718C>T) in the KNG1 gene causing severe HMWK deficiency. This case expands the mutational spectrum of this ultra-rare disorder and highlights that its primary clinical significance is an isolated APTT prolongation without a bleeding diathesis. Genetic diagnosis is crucial to avoid unnecessary treatments, surgical delays, and exposure to blood products in such patients.