RH BLOOD GROUP SYSTEM, genetic hemo

What determines Rh positivity or negativity?

D antigen on RBC membrane. Rh+ = D antigen present (genotypes: DD or Dd). Rh− = dd. No natural anti-D antibodies (unlike ABO)

What causes Rh incompatibility in pregnancy?

Rh- mother carries Rh+ fetus. Fetal D antigen enters maternal blood → anti-D IgG forms. Crosses placenta in next pregnancy → Hemolytic Disease of Newborn

Management of Rh isoimmunisation?

Anti-D antibody titration at 20, 28, 36 weeks. If titer >1:32, repeat every 4 weeks. Administer Rho(D) immune globulin to Rh- mothers

What are the interpretations in ABO testing with anti-A, anti-B, and anti-AB sera?

No agglutination: Group O. Agglutination in all: Group AB. Aggl. in anti-A/AB only: Group A. Aggl. in anti-B/AB only: Group B

Normal adult hemoglobins and their subunits?

HbA (\alpha2 \beta2) – Major form. HbA2 (\alpha2 \delta2) – 2.5%. HbF (\alpha2 \gamma2) – Present in F cells

What is HbS and its mutation?

Found in sickle cell disease. \beta-globin mutation: Glutamic acid → Valine at position 6. Causes Hb to form non-functional aggregates under hypoxia

Symptoms and complications of sickle cell anemia?

Vaso-occlusion (pain, stroke, splenic infarction). Hemolytic anemia → jaundice. Functional asplenia → infection risk. Chronic: growth delay, nephropathy, retinopathy

Management of sickle cell anemia?

Crisis mgmt: analgesics, O₂. Hydroxyurea → ↑ HbF. Vaccines against encapsulated bacteria. Blood transfusions in severe cases