Hemoglobinopathies

A haemoglobinopathy is a genetic disorder which alters the structure of haemoglobin ¹. The result is reduced oxygen-carrying capacity of the blood to the tissues, and other sequelae.

Clinical presentation

Clinical presentation varies, is related to hypoxia, and characteristically includes the following:

• claudication
• tachycardia
• dyspnea
• vertigo
• angina

Pathology

• vascular occlusion leading to infarcts
• necrosis
• pathological fracture
• osteomyelitis (100x more likely in sickle cell disease patients) ²

Classification

Types of haemoglobinopathies include the following, with the predominant type of abnormal haemoglobin in bracketsparentheses following the disorder.

• sickle cell disease (HbS)
• sickle cell trait (HbAS)
• sickle cell-haemoglobin C (HbSC)
• sickle cell-thalassemia (HbS and HbA)
• thalassemia
  • alpha thalassemia (deficient alpha-globin chain synthesis)
  • beta thalassemia (deficient beta-globin chain synthesis)
    • thalassemia major (homozygous) - Cooley anaemia
    • thalassemia minor (heterozygous)
• haemoglobin C disease (HbCC)
• haemoglobin C trait (HbAC)

Radiographic features

The radiographic features of hemoglobinopathies vary and some are generallymore specific for specific hemoglobinopathies (e.g. splenic sequestration in sickle cell). Generally, many common radiographic features are related to extramedullary hematopoiesis and infarctions as follows:

• extramedullary haematopoiesis
  • Erlenmeyer flask deformity
  • hair-on-end appearance (characteristic, not pathognomonic, of thalassemia)
  • rib expansion
  • calvarial alterations
    • diploic widening
    • outer table thinning
  • facial bone alterations
    • nasal and temporal bone expansion (obliteration of sinuses)
    • lateral displacement of orbits (hypertelorism)
    • dental displacement
• infarctions
  • epiphyseal ischemia (especially in the femoral head)
  • growth disturbances
  • osseous insufficiency
  • haemarthrosis
  • hand-foot syndrome (characteristic of sickle cell disease)