Rh deficiency syndrome
Findings
No curated finding names Rh deficiency syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
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.
Definition from the Mondo Disease Ontology (MONDO:0019107), read 2026-09-29. CC BY 4.0.
- Onset and course
- Miscarriage
HPO, annotations 2026-09-02
Features
19 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Decreased circulating haptoglobin concentrationHPOHP:0020181
- Very frequent (80% to 99% of cases)
- Hemolytic anemiaHPOHP:0001878
- Very frequent (80% to 99% of cases)
- Increased red cell osmotic fragilityHPOHP:0005502
- Very frequent (80% to 99% of cases)
- Positive direct antiglobulin testHPOHP:0032366
- Very frequent (80% to 99% of cases)
- ReticulocytosisHPOHP:0001923
- Very frequent (80% to 99% of cases)
Genes
3 genes
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- RHAGHGNC:10006
- Definitive · Ambry Genetics · Autosomal recessive · 2024
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2020
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
- HGNC:10008HGNC:10008
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
- HGNC:10009HGNC:10009
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
Other names
2 names
Resolves to: Rh deficiency syndrome
- Also called
- anemia, hemolytic, Rh-null, regulator typeRh-null syndrome