17.4 Pathology

• Introduction
  
• Hemoglobinopathies
  • Quantitative hemoglobinopathies (thalassemias)
  • Structural hemoglobinopathies (sickle cell syndrome)
• Myelopathies
  • Panmyelopathies
• Blood clotting disorders
  • Thrombocytopenias
  • Hereditary coagulopathies
• Disorders of the lymph vessels
• Immunologic disorders
  • Catch22
  • Myasthenia gravis

Myelopathies

Congenital myelopathies are very rare bone marrow diseases. They manifest initially in small or school age children.

Panmyelopathies

There are a number of hereditary panmyelopathies, i.e., functional disorders of the bone marrow, that affect all 3 cell types (red and white cells as well as the thrombocytes). The most frequent are summarized as follows.

The most frequent diseases of all three cell lines:

• Fanconi anemia
  
  
• Shwachman-Diamond syndrome (German)
  
  
• Dyskeratosis congenita
  

Blood clotting disorders

Congenital blood clotting disorders are caused by a genetic defect of the megakaryocytes (precursor of thrombocytes) or the plasmatic coagulation factors.

Thrombocytopenias

In the thrombocytopenias one distinguishes between two autosomal recessive hereditary forms:

• Amegakaryocytic thrombopenia
• Thrombocytopenia with radius aplasia

Hereditary coagulopathies

Today one knows many differing coagulopathies. Most of them are inherited autosomal recessively. The only exceptions are hemophilias A and B, which are X chromosomal recessively inherited.

Disorders of the lymph vessels

Primary lymphatic edema is subdivided into 3 groups:

• Congenital lymphatic edema is present already at birth: Milroy disease
• Somewhat later (mostly in adolescence but before age 35) lymphatic edema praecox commences: Meige disease
• Lymphatic edema tarda begins only after age 35.