Update on Microcytic Anaemias

Photis Beris, MD

Professor of Clinical Haematology Department of Internal Medicine, Geneva University Hospital Geneva, Switzerland

Achille Iolascon, MD, PhD

Medical Genetics Chair University Federico II – Naples CEINGE - Advanced Biotechnologies Naples, Italy Slide 1 of 27

Causes of Iron Deficiency Anaemia

• • • •

Blood loss Limited supply (poor diet) Increased requirements Iron malabsorption Hereditary Acquired

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Overview of Microcytic Anaemias and New Hereditary Forms

Achille Iolascon, MD, PhD

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Inherited Microcytic Anaemias Heme synthesis

• Porphyrias – Erythropoietic porphyria • Sideroblastic anaemias – X-linked – X-linked with ataxia – Autosomal recessive (due to glutaredoxin 5 or to Gly transporter deficiency)

Globin synthesis

• Thalassaemias • Haemoglobinopathies

Iron metabolism

• Hereditary hypotransferrinaemia • Aceruloplasminaemia • Divalent metal transporter 1 (DMT1) disease • Ferroportin disease • TMPRSS6 deficiency Slide 4 of 27 Graphics courtesy of Dr. Achille Iolascon.

Iron Compartments

Enterocyte: Transfer Erythroid Precursor: Use Macrophage: Recycling Hepatocyte: Storage

Iolascon A, et al.

Semin Hematol.

2009;46:358-370.

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Divalent Metal Transporter 1 (DMT1) Disease

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DMT1 Deficiency

delCTT intron 4 /

R416C

Severe microcytic anaemia with high transferrin saturation Severe hypochromia with liver iron overload and normal ferritin levels Graphics A, B, and Table with permission from Iolascon, A. et al.

Blood.

2006;107:349-354.

Top left graphic courtesy of Dr. Achille Iolascon.

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Mutations and Clinical Features of 3 DMT1 Patients Czech Homozygous Italian (Compound Heterozygous) French (Compound Heterozygous) Mutation

Functional studies G1285C, D399E (cytosolic loop) exon 12 skipping Reduced stability of del exon 13 mutation; Normal targeting and function of E399D mutation delCTT, intron 4 R416C, TM9 R416C, complete loss of function (defective processing and targeting, ER retention, loss of transport function) delVal 114, TM2, G212V, TM5 Not studied; G212V probably conservative mutation

Laboratory values

Hb at birth (g/L) 74 40 83 sTfR (mg/L) Liver iron Urinary hepcidin (ng/mg creatinine) 38 (N,1.9

–4.4) +++ (age 19 y) 1 –2 (N, 10–200) 6.77 (N, 0.83

–1.76) 2536 µg/g liver (N, 0– 400) 98 –102 (N, 45–115) 8.29 (N, 0.83

–1.76) 250 +/- 50 (age 9 y); µmol/g liver 66 µmol/g (after 3 mo epo) (N, <36) 19 –43 (on 2 separate occasions) (N, 45 –115) Abbreviations: Epo, erythropoietin; Hb, haemoglobin; N, normal values; sTfR, saturated transferrin receptor.

Iolascon A, et al.

J Pediatr.

2008;152:136-139. Slide 8 of 27

Clinical and Laboratory Findings of DMT1 Mutations

1,2 MCV

Serum iron Tf saturation sTfR BM sideroblasts FEP Liver iron Neonatal appearance Effect oral/IV Fe Serum or urinary hepcidin Inheritance Therapy 45 –55 fL ++ ++ ++ + +++ + -/ AR Epo • DMT1 is essential in erythropoiesis • DMT1 is not essential for liver iron uptake • DMT1 is not essential for duodenal iron absorption – Alternative pathways?

– Heme absorption?

• Increased iron absorption occurs in the presence of iron overload because of low hepcidin levels • Partial response of anemia to erythropoietin treatment 1. Iolascon A, et al.

Blood.

2006;107:349-354. 2. Iolascon A, et al.

J Pediatr.

Graphic courtesy of Dr. Achille Iolascon.

2008;152:136-139. Slide 9 of 27

Iron-Refractory Iron-Deficient Anaemia (IRIDA)

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Iron-Refractory Iron-Deficiency Anaemia (IRIDA) 1-7 MCV

Serum iron 47 –60 fL P686 fs Tf saturation sTfR BM sideroblasts FEP Liver iron Neonatal appearance Effect oral/IV Fe Serum or urinary hepcidin ++ + normal +/ +/ + E522K A118D S623T Inheritance Therapy AR -

All patients have high hepcidin levels!

1. Edison ES, et al,

Br J Haematol

. 2009 Aug 29. [Epub ahead of print]. 2. Tchou I et al.

Eur J Haematol

. 2009 Aug 25. [Epub ahead of print]. 3. Guillem F, et al.

Blood.

2008;112:2089-2091. 4. Finberg KE, et al.

Nat Genet.

2008;40:569-571. 5. Melis MA, et al.

Haematologica.

2008;93:1473-1479. 6. Ramsay AJ, et al.

Hum Mol Genet.

2009;18:3673-3683. 7. Silvestri L, et al.

Blood.

2009;113:5605-5608. Left graphic courtesy of Dr. Achille Iolascon. Right graphic with permission from Silvestri L, et al.

Blood

. 2009;113:5605-5608.

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IRIDA –Effect of Iron IV Administration

Hb, g/dL MCV, fL MCH, pg Serum Ferritin, μg/L Serum Iron, μg/dL Transferrin sat, % Patient I-1

(age 3 y) IV Iron Before Treatment After Treatment

Patient II-1

(age 3 y) IV Iron Before Treatment After Treatment

Patient II-2

(age 5 y) IV Iron Before Treatment After Treatment

Patient III-1

(age 3 y) IV Iron Before Treatment After Treatment 8.3

9.5

9.8

11 10.4

11.6

9.1

10.7

52 15 15 12 3 58 16 74 14 3.7

65 16.7

50 22 6.2

66.4

18 113 34.2

10.2

68 18 32 48 9.4

71.8

19 133 48 15.8

60 17 26 14 3.7

60 18 25 18 4.5

Abbreviations: Hb, haemoglobin; IV, intravenous; MCH, mean corpuscular haemoglobin; MCV, mean corpuscular volume; sat, saturation.

Unpublished data from Iolascon et al. Graphic courtesy of Dr. Achille Iolascon.

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The Role of TMPRSS6 in The Hepcidin Regulatory Pathway

Proteolytic cleavage BMP s-HJV m-HJV BMPRs TMPRSS6 SMAD 1-5-8 complex P SMAD 1-5-8 complex P SMAD 1-5-8 complex SMAD 4 P mRNA HAMP

Abbreviations: BMP, bone morphogenic protein; BMPR, bone morphogenic protein receptor; HJV, haemojuvelin; P, phosphorylation.

Silvestri L, et al.

Blood.

2009;113:5605-5608. Graphic courtesy of Dr. Achille Iolascon.

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How to Recognize an Atypical Microcytosis

• • • • •

Refractory (or partially refractory) to IV iron Noncongruent iron parameters: microcytosis + High transferrin saturation and high serum ferritin Low transferrin saturation and high serum ferritin Ringed sideroblasts (any percentage) Familial cases High hepcidin (TMPRSS6 mutations)

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Faculty Discussion

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Unexplained or Refractory Acquired Iron-Deficiency Anaemia

Photis Beris, MD

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Unexplained or Refractory Acquired Iron-Deficiency Anaemia (IDA)

• • •

Helicobacter pylori

Celiac disease Autoimmune atrophic gastritis

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Helicobacter pylori Infection

• • •

In recent years, H. pylori has been implicated in several studies as a cause of IDA refractory to oral iron treatment 1 – Favorable response to H. pylori eradication Mechanisms: Occult GI bleeding? Alterations in intragastric pH and ascorbic acid concentration? Induction of IL-1 β and TNF-α, (inhibitors of parietal cell function)? Induction of parietal cell apoptosis?

2 Diagnosis: IgG antibody screening, urease breath test 1

1. Hershko C, et al.

Semin Hematol.

2009;46:339-350.

2. Hershko C, et al.

Blood Cells Mol Dis.

2007;38:45-53. Slide 18 of 27

Celiac Disease

• •

Celiac disease is a common nonbleeding gastrointestinal condition that may result in refractory IDA 1 – Celiac disease accounts for 5%–6% of unexplained IDA cases – Approximately 50% of patients with subclinical celiac disease develop IDA Diagnosis: Anti-tissue transglutaminase antibodies and/or anti-endomysial antibodies

Slide 19 of 27 Hershko C, et al.

Semin Hematol.

2009;46:339-350.

Autoimmune Atrophic Gastritis

• • • •

Autoimmune atrophic gastritis, or atrophic body gastritis, is associated with chronic idiopathic IDA with no evidence of gastrointestinal blood loss Iron deficiency may develop many years before the depletion of vitamin B 12 stores Possible role of H. pylori in the pathogenesis of autoimmune gastritis due to antigenic mimicry of H + K + -ATPase Diagnosis: Serum gastrin, parietal cell antibodies

Slide 20 of 27 Hershko C, et al.

Semin Hematol.

2009;46:339-350.

Unexplained or Refractory Acquired IDA

300 Patients with IDA

Mean age 39 ± 18 y; 251/300 (84%) women of reproductive age

Adult Celiac Disease

H. pylori

Autoimmune Atrophic Gastritis 18 cases (6%); refractoriness 100% 77 cases (26%); 39/77 (51%) also had

H. pylori;

refractoriness 69% 57 cases (19%); coexisting in 165/300 (55%); refractoriness 68%

Hershko C, et al.

Blood Cells Mol Dis.

2007;39:178-183. Graphic courtesy of Dr. Photis Beris.

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Effect of Age on Autoimmune Gastritis

1,2 As age from 20 to 60 years Gastrin levels and vitamin B 12 levels and H. pylori prevalence

• •

With increasing age from <20 to >60 years, gastrin progressively increases and B12 decreases 1 HP infection decreases from 87.5% at age <20 years to 12.5% at age >60 years 1

1. Hershko C, et al.

Blood.

2006;107:1673-1679. 2. Hershko C, et al.

Blood Cells Mol Dis.

2007;39:178-183.

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Treatment

• •

Cure the underlying disease

•

In many cases, H. pylori eradication will cure the anaemia without iron therapy

•

IV iron therapy is indicated in autoimmune atrophic gastritis due to malabsorption When IV iron is used, always calculate the precise amount of iron needed to correct anaemia and to replenish iron stores

Slide 23 of 27 Hershko C, et al.

Semin Hematol.

2009;46:339-350.

Recommendations for the Diagnostic Work-Up of Unexplained or Refractory Acquired IDA

• •

Screening for celiac disease, autoimmune atrophic gastritis and for H. pylori should be performed in the following populations: Males and postmenopausal females with IDA and negative endoscopic and radiologic studies Fertile females and children/adolescents refractory to oral iron treatment

Hershko C. In:

Disorders of Iron Homeostasis, Erythrocytes, Erythropoiesis.

Forum service editore: Genoa, Italy; 2006.

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Acquired IDA —Conclusions

• • • • •

Blood loss, insufficient dietary iron intake, and increased iron requirements are the main causes of iron deficiency anaemia. Acquired decreased iron absorption has recently been recognized in patients with unexplained or refractory IDA Celiac disease, autoimmune atrophic gastritis, and H. pylori infection are increasingly diagnosed in such patients In some cases, H. pylori may be directly implicated in the genesis of autoimmune gastritis We strongly recommend a diagnostic work-up for these conditions in case of acquired refractory or obscure IDA

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Faculty Discussion

Part of the information given in the answers to the questions was taken from the electronic edition of “Up to-date” chapter “pathogenesis, epidemiology, and clinical manifestations of celiac disease in adults” written by Detlef Schuppan MD, PhD, and Walburga Dieterich, PhD, version 17.2 January 27, 2009.

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