A novel homozygous ABCB6 variant causing the Lan null phenotype and anti‐Lan‐mediated hemolytic disease of the fetus and newborn: A case report and a review of anti‐Lan in pregnancy

Background The Lan antigen is a high‐prevalence red blood cell antigen encoded by the ATP binding cassette subfamily B member 6 ( ABCB6 ) gene. Variants in this gene are responsible for Lan null and variant phenotypes. Individuals lacking the Lan antigen may develop anti‐Lan antibodies following sensitizing events such as transfusion or pregnancy. Hemolytic disease of the fetus and newborn (HDFN) caused by anti‐Lan antibodies is extremely rare. Case Presentation We report a case of a Chinese pregnant woman carrying a novel homozygous variant in exon 17 of the ABCB6 gene (NM_005689.4:c.2312_2313del), resulting in a Lan null phenotype. Anti‐Lan antibodies were detected in maternal plasma, neonatal plasma, and cord blood eluate. The newborn developed mild HDFN, which resolved spontaneously without intervention, leading to a favorable outcome. Conclusion This represents the first documented case of anti‐Lan‐mediated HDFN in an Asian population and the fifth case worldwide. Our findings expand the genetic diversity and geographic spectrum of this rare condition and provide important insights for clinical management.