has material basis in germline mutation in RHAG familial hemolytic anemia Rh deficiency syndrome https://github.com/monarch-initiative/mondo/issues/4521 https://rarediseases.info.nih.gov/diseases/12916/rh-deficiency-syndrome https://www.malacards.org/card/hemolytic_disease_of_fetus_and_newborn_rh_induced https://www.malacards.org/card/rh_null_regulator_type icd11.foundation:1554765420 OMIM:268150 MONDO:0019107 RH-null, regulator type The Rh deficiency syndrome, also known as Rh-null syndrome, is a blood disorder where people have red blood cells (RBCs) lacking all Rh antigens. The Rh antigens maintain the integrity of the RBC membrane and therefore, RBCs which lack Rh antigens have an abnormal shape. There are two types of Rh deficiency syndrome: The regulator type is associated with many different changes (mutations) in the RHAG gene. The amorph type is caused by inactive copies of a gene (silent alleles) at the RH locus. As a result, the RBCs do not express any of the Rh antigens. The absence of the Rh complex alters the RBC shape, increases its tendency to break down (osmotic fragility), and shortens its lifespan, resulting in a hemolytic anemia that is usually mild. These patients are at risk of having adverse transfusion reactions because they may produce antibodies against several of the Rh antigens and can only receive blood from people who have the same condition. Rh deficiency syndrome is inherited in an autosomal recessive manner. Management is individualized according to the severity of hemolytic anemia. SCTID:37272000 DOID:0050641 RHNR Orphanet:71275 RHN anemia, hemolytic, Rh-null, regulator type MESH:C562717 Rh-null syndrome MEDGEN:75772 UMLS:C0272052 Rh deficiency syndrome GARD:0012916 hereditary stomatocytosis