Hereditary Spherocytosis Ian Roberts

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HereditarySpherocytosisIan Roberts
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• Introduction
• Causes
• Symptoms
• Laboratory Studies
• Treatment
• Case Study

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Introduction

• Red blood cell membrane disorder
• Spherically shaped red blood cells
• Most common inherited anaemia in northern
  European descendants - 1 in 2500
• Membrane loss due to defects in membrane
  proteins ankyrin, band 3, spectrin and protein
  4.2

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Causes

• Mutations causing defects in membrane proteins
• Cause defective or deficient proteins
• Affect biconcave shape of red cell

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Causes

• Mutations causing defects in membrane proteins
• Cause defective or deficient proteins
• Affect biconcave shape of red cell
• Red cells lose shape and become spherical with no
  flexibility
• Unflexible spherocytes get caught up in spleen
  and phagocytosed

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Symptoms

• Can range from asymptomatic to severe haemolysis
• Anaemia
• Jaundice
• Fatigue
• Splenomegaly

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Laboratory Studies

• FBC Retics
• Blood film
• Bilirubin
• LDH
• Osmotic Fragility
• Dye Binding

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Laboratory Studies

• ? Hb
• ? Retics
• ? Bilirubin
• ? LDH
• ? spherocytes on blood film

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Normal RBC
Spherocyte
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Laboratory Studies

• ? Hb
• ? Retics
• ? Bilirubin
• ? LDH
• ? spherocytes on blood film
• ? osmotic fragility
• ? dye binding

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Osmotic Fragility

• Expose RBC to decreasing saline concentrations
• As saline decreases RBC absorb more
• Normal RBC can swell due to flexibility of
  membrane, therefore are more resistant to low
  saline
• Spherocytes are unflexible, therefore cannot
  absorb more - ? haemolysis

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Haemolysis
? Decreasing Saline
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Dye Binding

• Flow cytometric method
• EDTA anticoagulated peripheral blood incubated
  with Eosin-5-Maleimide (E5M)
• Binds to normal red cell membrane proteins
• As dye passes through a laser, it emits light
  allowing quantitation
• HS patients will have reduced dye binding

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Normal
HS transfused
HS
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• Osmotic Fragility
• Must be performed within 6 hrs
• 24hours
• 3ml blood
• Unreliable on patients recently transfused
• Sensitivity 80 (mild cases missed)
• Abnormal in other causes of spherocytosis (AIHA)

• Flow Cytometry
• Reproducible up to 72hrs
• 1hour
• 100ul blood
• Results abnormal after blood transfusion
• Sensitivity 93
• Specificity 99
• SEA Ovalocytosis Abnormal in CHAD

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Treatment

• Phototherapy and/or exchange transfusion in
  neonates with severe hyperbilirubinaemia
• Partial/total splenectomy
• Folic acid supplements sustain erythropoiesis

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Case Study 1

• Patient A was born in June 2007
• First week Hb dropped slowly, then after 2 weeks
  sudden drop
• Bilirubin was high for first 3 weeks, but
  decreased after several transfusions and
  phototherapy
• Haematologist suggested tests to confirm HS

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Date 20/06/2007 12/06/2007
08/06/2007 05/06/2007 HB 7.3
11.2 14.3
16.7 WBC 16.6
16.6 14.4
14.1 PLT 467
467 296
240 Date 20/06/2007 12/06/2007
08/06/2007 07/06/2007 06/06/2007
05/06/2007 05/06/2007 TBIL 76
110 182 211
238 340 343

• Osmotic fragility test requested on 12/6/07
• Very uncommon test - time consuming
• - lack of reagents
• - lack of trained staff

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Case Study 1

• Sample sent for Dye binding (very first sample
  sent)

Dye Binding 0.72 units
( 0.80 to 1.20 ) Comments
Reduced dye binding, consistent with diagnosis of
hereditary spherocytosis.
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Case Study 2

• Patient B was born in November 2009
• First 3 weeks Hb normal, then sudden drop
• Bilirubin was high for first 3 weeks, but
  responded to phototherapy
• Haematologist suggested repeating tests 4 months
  after birth

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Date 02/03/2010 14/12/2009 11/12/2009
23/11/2009 22/11/2009 21/11/2009
HB 7.1 8.9
7.7 14.4 16.1
14.5 WBC
7.8 16.5 11.2
9.7 16.6
17.8 PLT 604
582 679
332 245 316
RBC 2.85 2.90
2.45 4.18
4.53 4.14 HCT
0.230 0.260 0.230
0.410 0.450
0.410 Date 02/03/2010
11/12/2009 23/11/2009 22/11/2009 21/11/2009
20/11/2009 TBIL 18 58
164 190 149 103
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Case Study

• Sample sent for Dye binding
• Patient A and Patient B are sisters

13/04/2010 Dye Binding 0.76
units ( 0.80 to 1.20 )
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Case Study

• Strong family history of HS
• Mother has HS splenectomy in 1991
• Maternal aunt has HS
• Maternal Grandmother has HS
• ? Paternal history of HS