LuLu phenotype

Autosomal recessive inheritance of the Lutheran null blood group phenotype is extremely rare, and has been reported in only 5 individuals. There is no obvious associated clinical or hematologic pathology, and all patients have been identified through identification of anti-Lu3 antibodies in their serum (Karamatic Crew et al., 2007). The Lutheran inhibitor blood group phenotype (In(Lu); 111150) is characterized phenotypically by the apparent absence of the Lu antigen on red blood cells during serologic tests, i.e. Lu(a-b-). Since it is inherited as an autosomal dominant trait, it was initially postulated to result from an inhibitor of the Lu antigen. However, Singleton et al. (2008) found that the phenotype results from a mutation in the transcription factor KLF1 that regulates expression of the BCAM gene. These 2 forms of Lutheran absence on red blood cells can be differentiated both by the pedigree and by serologic studies. An X-linked recessive form (309050) has been rarely reported. [from OMIM]