Much of the progress in the diagnosis, classification, and treatment of childhood hematological disorders has come from a partnership between clinicians and scientists. Indeed, access to molecular techniques is now an integral part of the practice of modern pediatric hematology. The aim of Pediatric Hematology: Methods and Protocols is to provide a collection of scientific protocols that cover the major aspects of the discipline. Most clinicians will be familiar with the difficulties inherent in establishing the underlying diagnosis in genetic marrow failure syndromes. A particular concern is failure to diagnose those associated with DNA repair defects. In Chapter 1, Dokal and colleagues present simple protocols for the molecular investigation of Fanconi anemia and dyskeratosis congenita. Molecular diagnosis is also important in children with congenital pure red cell aplasia, owing to the highly variable phenotype of this condition. In Chapter 2, Ball describes relevant protocols for the investigation of Diamond-Blackfan anemia. Hereditary hemoglobinopathy is a major cause of death and morbidity throughout the world. This area has seen great advances in screening and antenatal diagnosis. In Chapter 3, Old details protocols for the molecular diagnosis of most forms of hemoglobinopathy. High-quality, accurate molecular testing on small amounts of material has been fundamental to progress in antenatal diagnostics. The introduction to his comprehensive chapter includes a discussion of the general principles that underpin these studies. In contrast to hemoglobinopathy, severe hemophilia is uncommon.