KATELYN BRIER

The case of the not so mild HDFN

Baby Billie’s Presentation of Complications

� A newborn, Baby “Billie-Rubin”, appears to be having complications after birth� Jaundiced skin

� Low RBC count- 1.66 x 106/uL

� Low Hgb- 7.4 g/dL

� High neonate bilirubin- 18.6 mg/dL

� Respiratory distress

� Possible HDFN is suspected

Hemolytic Disease of the Fetus and Newborn

� Defined as the destruction of fetal and newborn red cells by maternal alloantibodies specific for inherited paternal red cell alloantigens

� Maternal IgG antibody is transported across the placenta where it targets the corresponding red cell antigen in the fetus’ circulation

� Targeted red cells are then destroyed by macrophages in the fetal spleen

HDFN

� In utero, the hemoglobin and bilirubin from the RBC destruction is cleared from circulation by the maternal liver.

� After birth, the baby’s liver is too immature to conjugate the bilirubin to clear it and jaundice occurs.

� Too much unconjugated bilirubin causes serious brain damage called kernicterus� Neurological deficits, abnormal reflexes and eye movements,

and seizures

Signs of HDFN

� Jaundice

� Hyperbilirubinemia

� Anemia

� Erythroblastosis fetalis- increase of premature nucleated red cells in circulation

� Respiratory distress

� Thrombocytopenia

� Severe- Kernicterus

HDFN

� ABO incompatibilities between mother and baby are typically mild to moderate cases� Treat the baby’s jaundice with UV lights

� ABO antibodies are primarily IgM naturally occurring antibodies directed against the missing A and B antigens� O mother’s have IgG as the primary anti-A and anit-B

isoantibody

� A and B mother’s primarily have IgM isoantibodies, but a small amount of IgG antibody can be present

Mother’s Prenatal History

� Mother “Peg Nancy” had previously been typed during her prenatal care� Had an ABO discrepancy

� Typed as a possible subgroup of A

� A2 is not as common as A1

� No unexpected antibodies were detected in the antibody screen

The Mother’s Testing

� Mother Peg Nancy’s typing had an ABO discrepancy

� Forward type looks like an A, reverse looks like an O

� The A1 cells should be negative

� Subgroup of A is investigated� A1 is the most common subtype of A by 80%

� A2 is the second most common by 20%

� A3, Ax, Am, and Ael are extremely weak and rare subgroups

Anti A Anti B Anti-D A1 cells B cells

4+ 0 4+ 1+ 4+

Phenotype Occurrence

Type Caucasians (%) Blacks (%)

A1 33 19

A2 10 8

B 9 20

O 44 49

A1B 3 3

A2B 1 1

The Mother’s Testing

� To determine the Mother Peg Nancy’s unique A group, antigen typing is performed with Anti-A1 against A1 cells, A2 cells, and the mother’s cells

� Mother is presumed to be an A2 type because she is negative to A1

A1 (Pos control)

A2(Neg control)

Mother

Anti-A1 4+ 0 0

Interpretation A1 + A1 = A1 =

The A2 Subgroup

� Is a weak subgroup of A and is recessive to A1

� It’s a result of a nucleotide deletion and frameshift � Causes an enzyme with an additional 21 amino acids at the C

terminus of the molecule

� Compared to A1, A2 only has 1/5th the amount of antigen sites as A1.� Fewer antigen sites make it a weak A because there was

inefficient conversion of H antigen to A antigen.

� Can test with anti H lectin to type A2. A1 will not react with anti H while A2 will.

� A2 individuals can develop an anti-A1 that is IgM in nature

H antigen vs A and B antigenswww.ncbi.nlm.nih.gov

The Baby’s Testing

� Baby Billie-Rubin’s forward type, Ab screen, and DAT were performed from a heelstick� Only forward type is performed because baby has not

developed antibodies yet

Anti A Anti B Anti-D Monoclonal control

DAT

3+ 4+ 4+ 0 3+

SC I SC II SC III

0√ 0√ 0√

The Baby’s Testing

� A and B cells are tested with the antibody screen to determine if the mother’s ABO antibodies are crossing the placenta

� Positive result is from the mother’s anti B that crossed the placenta� Babies do not develop ABO isoantibodies until 3 to 6 months,

so if present, they are from the mom

A cells B cells

0 3+

The Baby’s Testing

� Baby Billie-Rubin typed as A2B

� A2B is a rare type; found in 1% of the population

� A2 is from the mother and B is from the father� Antigen typing was used again to determine the possible A2 type

� 25% of A2B individuals have an alloanti-A1 in their sera

� Important to find compatible blood to prevent development of an anti-A1

A1 (Pos control)

A2(Neg control)

Baby

Anti-A1 4+ 0 0

Interpretation A1 + A1 = A1 =

Anti B

� Anti B in an A mother is typically IgM in nature

� There have only been a few cases reported of IgG anti B in A2 mothers causing HDFN in B type babies

� IgG anti B can be naturally occurring, but is in small quantities

� A higher titer IgG anti-B may be naturally occurring or develop after being sensitized to B antigens in previous pregnancies

The Baby’s Laboratory Results

RBC (at birth 3.9-0.65 x103 /uL)

Bilirubin Direct (0.0-0.3 mg/dL)

Bilirubin Total (0-1 day old 1.4-8.7 mg/dL)

Day 101:15

Day 105:17

Day 117:30

Day 205:35

Day 305:00

1.66 4.58 3.75 3.60 3.57

Day 101:15

Day 105:17

Day 117:30

Day123:30

Day 205:35

Day 305:00

0.8 0.5 0.7 0.6 0.6 0.6

Day 101:15

Day 105:17

Day 117:30

Day 123:30

Day 205:35

Day 305:00

18.6 9.8 12.7 10.5 9.5 6.1

Laboratory Significance

� RBC- the count is below the normal range for a newborn, showing that RBC destruction is occurring� Baby won’t be receiving enough oxygen to tissues when RBC

count is low

� Bilirubin Direct- bilirubin by product of RBC destructionn; direct measures the conjugated bilirubin

� Bilirubin Total- measures the conjugated and unconjugated bilirubin present in high levels in RBC destruction� High levels of bilirubin in the baby’s system can cause brain

damage if untreated (kernicterus)

The Baby’s Laboratory Results

Hemoglobin (14.5- 22.5 g/dL)

Platelets (150-400 x103 /uL)

NRBC (0 %)

Day 101:15

Day 105:17

Day 117:30

Day 2 05:35

Day 305:00

Day 404:00

214 57 66 69 77 106

Day 101:15

Day 105:17

Day 117:30

Day 205:35

Day 305:00

202 128 49 22 4

Day 101:15

Day 105:17

Day 117:30

Day 2 05:35

Day 305:00

Day 404:00

7.4 14.1 11.6 11.2 10.8 12.7

Laboratory Significance

� Hemoglobin- decrease of hemoglobin is seen in an increase of RBC destruction; there is free hemoglobin that gets broken down into bilirubin

� Platelets- a decrease in platelets is a result of intravascular hemolysis from the HDFN� Platelets are being consumed as RBC’s are being destroyed

� NRBC- increased when the bone marrow is trying to push out more RBCs sooner to compensate for a RBC decrease

Treatment

� Transfusion was performed to treat the anemia

� O negative type blood was used� Blood needs to be compatible with mother and baby since baby

has mom’s antibodies

� AB Fresh Frozen Plasma� FFP needs to be compatible with baby and donor cells

� Baby’s lab results improved to a better level after the transfusion and use of phototherapy, and continued to reach normal levels as time progressed as the antibody decreased

Summary

� A2 mother gives birth to an A2B baby who is experiencing HDFN

� HDFN is determined to be caused by an IgG anti B from the mother

� Only IgG antibodies cross the placenta

� Mother either had a high titer of natural IgG anti-B or was sensitized from a previous pregnancy

� Baby was treated with phototherapy and a transfusion

References

� Roback, John D.; et al. Technical Manual. AABB. 17th

edition. 2011.

� Chaudhari, Surg; et al. Transfusion in Blood Groups A2B with Anti A Recipient. 2008. 64:371-372.

� Jeon, H.; Calhoun, B.; et al. Significant ABO hemolytic disease of the newborn in a group B infant with a group A2 mother. Immunohematology. 2000. 16(3):105-108.

� Mckenzie, Shirlyn; William, J. Lynne. Clinical Laboratory Hematology. 2nd edition. 2010.

Special Thanks

Mary SignaigoClinical Laboratory Educator at Mercy Hospital St. Louis

Dr. LudwigPathologist at Mercy Hospital St. Louis