Case report and literature review: transient Inab phenotype and an agglutinating anti‐IFC in a patient with a gastrointestinal problem

Abstract

This is the first example of a direct-agglutinating anti-IFC. The cause of the transient depression in CD55 protein (and thus Cromer system antigens) and appearance of anti-IFC remains unknown, as does the relationship between the patient's GI system abnormalities and these serologic findings.

CD55 Deficiency, Early-Onset Protein-Losing Enteropathy, and Thrombosis

“…CD55 deficiency has been previously found in persons with sporadic gastrointestinal abnormalities and lacking Cromer Blood Group red blood cell antigens (the Inab phenotype). 34–37 The Inab phenotype can be transient (3 cases) or persistent (9 cases), and sometimes associated with GI disease variously diagnosed as Crohn’s, capillary angioma, protein-losing enteropathy with intestinal tumor, and food intolerances. Three loss-of-function variants were identified (Fig.…”

An autoanti‐Kpb immunoglobulin M that simulates antigen suppression

“…It has also been proposed that the antibody causes generation of antigen‐negative RBCs during production in the marrow; however, at least in some cases, this has been ruled out by observing the loss of antigen on transfused RBCs (both autologous and allogeneic) 1,2,4,5 . The antigen loss phenomenon has been observed in Kell, 2,4‐8 Kidd, 1,9,10 Rh, 11,12 Ge, 3 and Cromer 13 systems, but has been seen most often in the context of Kell antigens and for Kp b in particular 4,6,8 …”

Adaptive immunity selects against malaria infection blocking mutations

“…FY � O always involves exactly the same promoter region mutation (T>C at position -33). By contrast, the Inab phenotype has been shown to be caused by at least three different mutations [49], and the Lan null phenotype by at least ten [50].…”

“…falciparum blocking mutations are unlikely to be responsible since one OK - woman is noted to have had 5 children [ 46 ], and the Inab phenotype has been reported in a 91 year old Japanese woman [ 47 ] and an 86 year old Italian American woman and her 70 year old brother [ 48 ]. Some Inab phenotype individuals suffer gastrointestinal problems but others do not [ 49 ]. The Lan null phenotype is only clinically relevant for blood transfusions or rare instances of foetal-maternal incompatibility of blood type [ 50 ].…”