Treatment of the hematological manifestations of dyskeratosis congenita

A non-canonical function of telomerase RNA in the regulation of developmental myelopoiesis in zebrafish

Dyskeratosis congenita (DC) is an inherited disorder with mutations affecting telomerase or telomeric proteins. DC patients usually die of bone marrow failure. Here we show that genetic depletion of the telomerase RNA component (TR) in the zebrafish results in impaired myelopoiesis, despite normal development of haematopoietic stem cells (HSCs). The neutropenia caused by TR depletion is independent of telomere length and telomerase activity. Genetic analysis shows that TR modulates the myeloid-erythroid fate decision by controlling the levels of the master myeloid and erythroid transcription factors spi1 and gata1, respectively. The alteration in spi1 and gata1 levels occurs through stimulation of gcsf and mcsf. Our model of TR deficiency in the zebrafish illuminates the non-canonical roles of TR, and could establish therapeutic targets for DC.

Bone marrow transplantation for inherited bone marrow failure syndromes

The inherited bone marrow failure (BMF) syndromes are characterized by impaired hematopoiesis and cancer predisposition. Most inherited BMF syndromes are also associated with a range of congenital anomalies. Progress in improving the outcomes for children with inherited BMF syndromes has been limited by the rarity of these disorders, as well as disease-specific genetic, molecular, cellular, and clinical characteristics that increase the risks of complications associated with hematopoietic stem cell transplantation (HSCT). As a result, the ability to develop innovative transplant approaches to circumvent these problems has been limited. Recent progress has been made, as best evidenced in studies adding fludarabine to the preparative regimen for children undergoing unrelated donor HSCT for Fanconi anemia. The rarity of these diseases coupled with the far more likely incremental improvements that will result from ongoing research will require prospective international clinical trials to improve the outcome for these children.

Treatment of dyskeratosis congenita with granulocyte-macrophage colony-stimulating factor and erythropoietin

Dyskeratosis congenita (DC) is a rare inherited disorder characterized by reticulate skin pigmentation, nail dystrophy, mucosal leucoplakia, and bone marrow failure. Pancytopenia is difficult to manage in patients with this disorder. We describe a 13-month-old-boy who presented with reticulate skin lesions, paleness, and hepatosplenomegaly. Anemia and leukopenia developed by the age of 43 months. The patient was treated with granulocyte-macrophage colony-stimulating factor (GM-CSF) (5 microg/kg/d, subcutaneously) for 19 months and erythropoietin (150 U/kg 3 days in a week, subcutaneously) for 8 months, with excellent neutrophil and hemoglobin response. Recurrent infections were not developed after starting GM-CSF, and packed red blood cell transfusion was not given to the patient after starting erythropoietin. GM-CSF combined with erythropoietin may be used in the treatment of bone marrow failure in patients with DC without an HLA-identical donor.

Unusual complications after bone marrow transplantation for dyskeratosis congenita

Dyskeratosis congenita (DC) is a rare inherited disorder often associated with aplastic anaemia. We report the cases of five boys transplanted with an HLA-identical related donor for severe aplastic anaemia (SAA) associated to DC; in all cases successful engraftment was observed. Three patients died 2-8 years after bone marrow transplantation (BMT) with signs of endothelial cell damage syndrome (kidney microangiopathy and liver veno-occlusive disease). Another boy died 1 year after BMT from Evans syndrome and invasive aspergillosis. One boy currently presents anaemia, polyarthritis of unknown origin, pulmonary fibrosis and gut malabsorption 7.5 years after BMT. SAA associated with DC can be successfully treated by allogeneic BMT. However, these early and late complications observed are very unusual after BMT and probably reflect the association of transplanted-related factors, evolution of the underlying disease, and increased sensitivity of endothelial cells. Modified conditioning approaches, advances in supportive care and surveillance of these unusual complications offer the possibility of improved outcome for these patients.

Dyskeratosis congenita: multisystemic disorder with special consideration of immunologic aspects. A review of the literature

Dyskeratosis congenita (DC) is a rare, predominantly X-linked multisystemic disorder. It demonstrates a wide spectrum of clinical manifestations and typically presents with dermatologic symptoms during the first decade of life. This review of the literature points out the importance of hematologic and immunologic alterations in defining the course and prognosis of the disease process. Pancytopenia as well as the humoral and cellular disturbances in immunologic functions associated with this disease complex may lead to severe infections that represent the main cause of death. The pathogenesis of DC is still unclear and a curative therapy is presently lacking. Recent reports suggest that a beneficial effect may be observed in the administration of hematopoietic growth factors (G-CSF, GM-CSF) for patients with DC and neutropenia.

Reticulate hyperpigmentation

Disorders that are characterized by a reticulate pattern of pigmentation are reviewed. Dyskeratosis congenita (DKC) is the prototype of these. In addition to reticulate hyperpigmentation, mucosal leukoplakia, bone marrow dysfunction, cytogenetic instability, and a predisposition to malignancy are characteristic of DKC. The most common pattern of inheritance is X-linked, with heterozygous females showing variable expression, most likely depending on tissue-specific patterns of random X-inactivation. Other reticulate pigmentary disorders reviewed include the Naegeli-Franceschetti-Jadassohn syndrome, X-linked reticulate pigmentary disorder, dermatopathia pigmentosa reticularis, Dowling-Degos disease, dyschromatosis, confluent and reticulated papillomatosis of Gougerot and Carteaud, reticulate acropigmentation of Kitamura, and Revescz syndrome. Diagnosis, treatment, and sometimes genetic counseling remain problematic for these entities. The pathophysiology of these disorders is unknown, but will certainly be aided greatly by the future identification of the underlying genes.

Effective stimulation of neutropoiesis with rh G-CSF in dyskeratosis congenita: a case report

Dyskeratosis congenita (DC) is a rare congenital X-linked disorder. The major clinical manifestations are abnormal skin pigmentation, nail dystrophy, and leukoplakia of mucosal membranes. About 50% of the patients develop bone marrow failure, which is partly responsible for the poor prognosis. Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) has been administered to some neutropenic patients with DC, but only a moderate stimulation of neutropoiesis has been observed. We report on a patient with DC treated with recombinant human granulocyte-colony-stimulating factor (rhG-CSF). This treatment resulted in a substantial dose-dependent increase in the neutrophil count.