Pathogenesis of aplastic anemia.

Aplastic anemia (AA) is a rare and life-threatening bone marrow failure (BMF) that results in peripheral blood cytopenia and reduced bone marrow hematopoietic cell proliferation. The symptoms are similar to myelofibrosis, myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) making diagnosis of AA complicated. The pathogenesis of AA is complex and its mechanism needs to be deciphered on an individualized basis. This review summarizes several contributions made in trying to understand AA pathogenesis in recent years which may be helpful for the development of personalized therapies for AA.

Aplasia medular grave adquirida: evolución histórica de los resultados obtenidos con trasplante de progenitores hematopoyéticos de donante familiar. Estudio del Grupo Español para el Trasplante de Médula Ósea en Niños (GETMON) / Severe acquired aplastic anemia: historical outcome of patients treated by allogeneic bone marrow transplantation from matched sibling donors. A study by the Spanish Group for Bone Marrow Transplantation in Children (GETMON)

Introducción: El trasplante de progenitores hematopoyéticos (TPH) de donante familiar compatible es el tratamiento de elección en la aplasia medular adquirida (AMA) grave en la infancia. Se presenta la experiencia de Grupo Español para el Trasplante de Médula Ósea en Niños en esta enfermedad a lo largo del período cronológico 1982-2004. Pacientes y métodos: Recibieron un trasplante 62 pacientes con una mediana de edad de 10 años. En el período 1982-1990 lo recibieron 18 pacientes y en el período 1991-2004, 44. El régimen de acondicionamiento varió según el período cronológico; en el primero se utilizó preferentemente la asociación de radioterapia y ciclofosfamida (72 % de los casos) y en el segundo ciclofosfamida con o sin globulina antitimocitaria (62 %). La profilaxis de enfermedad injerto contra huésped más utilizada fue la ciclosporina (57/62 pacientes). Resultados: Un total de 51 pacientes están vivos y en remisión completa de su aplasia con períodos de observación de entre 24 y 289 meses (mediana de 127 meses). La probabilidad de supervivencia actuarial libre de eventos a 5 años es del 82 %. Dicha supervivencia se incrementó del 61 al 90 % entre los dos períodos analizados. Un total de 11 pacientes fallecieron por fracaso o pérdida del injerto (3), enfermedad injerto contra huésped aguda o crónica asociada a infecciones (4) o fallo multiorgánico (4). El análisis univariante evidenció dos factores con valor predictivo para la supervivencia: el intervalo diagnóstico/trasplante y el período cronológico en que se efectuó (en ambos, p = 0,03). Conclusiones: Esta experiencia confirma que el trasplante de progenitores hematopoyéticos de donante familiar compatible es el tratamiento de elección para la aplasia medular grave adquirida, con un porcentaje de supervivencia libre de episodios del 90 % en la actualidad (AU)

Allogeneic haematopoietic stem-cell transplantation is the treatment of choice for acquired aplastic anaemia in children. Experience with this approach from Spanish Working Party for Bone Marrow Transplantation in Children in two sequential time periods (1982-1990 and 1991-2004) is reported. Patients and methods: Sixty two consecutive patients with a median age of 10 years were transplanted; 18 in the 1982-1990 period and 44 in the 1991-2004 period. Conditioning regimen consisted mainly of irradiation and cyclophosphamide in the first period (72 % of patients) and cyclophosphamide ± anti-thymocyte globulin (62 %) in the second. Graft versus host disease prophylaxis consisted of cyclosporine in most patients (57/62). Results: Fifty one patients are alive and disease-free at a median follow-up of 127 months. Five years probability of event-free survival is 82 %. The survival increased from 61 % to 91 % during the two time periods. Eleven patients died from graft failure or rejection (3), acute or chronic graft versus host disease and infection (4) or multi-organ failure (4). Univariate analysis identified two significant prognostic factors: interval diagnostic/transplant and time period of transplant (for both p = 0.03). Conclusions: This experience corroborates that allogeneic haematopoietic stem-cell transplantation is the best treatment for severe acquired aplastic anaemia, with a current disease - free survival of 90 % of patients (AU)

Congenital amegakaryocytic thrombocytopenia in three siblings: molecular analysis of atypical clinical presentation.

OBJECTIVE: An 11-year-old girl, presenting with fatigue and bruising, was found to be profoundly pancytopenic. Bone marrow exam and clinical evaluation were consistent with aplastic anemia. Family members were studied as potential stem cell donors, revealing that both younger siblings displayed significant thrombocytopenia, whereas both parents had normal blood counts. We evaluated this pedigree to understand the unusually late presentation of congenital amegakaryocytic thrombocytopenia (CAMT). MATERIALS AND METHODS: The coding region and the intron/exon junctions of MPL were sequenced from each family member. Vectors representing each of the mutations were constructed and tested for the ability to support growth of Baf3/Mpl(mutant) cells. RESULTS: All three siblings had elevated thrombopoietin levels. Analysis of genomic DNA demonstrated that each parent had mutations/polymorphisms in a single MPL allele and that each child was a compound heterozygote, having inherited both abnormal alleles. The maternal allele encoded a mutation of the donor splice-junction at the exon-3/intron-3 boundary. A mini-gene construct encoding normal vs mutant versions of the intron-3 donor-site demonstrated that physiologic splicing was significantly reduced in the mutant construct. CONCLUSIONS: Mutations that incompletely eliminate Mpl expression/function may result in delayed diagnosis of CAMT and confusion with aplastic anemia.

Congenital aplastic anemia caused by mutations in the SBDS gene: a rare presentation of Shwachman-Diamond syndrome.

CLINICAL FINDINGS: Aplastic anemia was diagnosed at birth for a first child from healthy nonconsanguineous parents. The girl had hypoglycemia, which normalized within 2 months. Cow milk allergy was suspected initially, because of skin lesions and diarrhea, followed by severe growth retardation. Clinical and radiologic symptoms gradually became typical for Shwachman-Diamond syndrome. Two common mutations in the SBDS gene (183-184TA-->CT [K62X] and IVS2(258)+2T--> C [C84fs]) were found. RESULTS: Bone marrow transplantation from a matched unrelated donor was unsuccessful. The genetic information from the deceased patient enabled us to perform prenatal molecular studies during the subsequent pregnancy, successfully predicting a nonaffected child. CONCLUSIONS: This report describes for the first time the hematologic abnormalities of congenital aplastic anemia and prolonged neonatal hypoglycemia as the presenting symptoms of Shwachman-Diamond syndrome. The finding of common mutations in the presence of these symptoms at birth suggests the lack of a clear phenotype-genotype relationship in this syndrome.

Chromosomal transformation in donor cells following allogeneic bone marrow transplantation.

We report here a monosomy 7 transformation of donor cells following matched-unrelated, same sex, allogeneic bone marrow transplantation in a patient with severe congenital aplastic anemia. A PCR technique was employed to amplify microsatellite markers on chromosome 7 to confirm donor/recipient identity. We found that the transformation of monosomy 7 occurred in previously genetically normal donor cells. This study suggests that the microenvironment of the bone marrow of our patient with severe congenital aplastic anemia may have played a critical role in the development of monosomy 7 of normal donor cells and we conclude that chromosomal microsatellite marker analysis can be a valuable tool for precise donor/recipient differentiation in engraftment monitoring.

Telomere length variation and telomerase activity expression in patients with congenital and acquired aplastic anemia.

Telomeres represent the nucleoprotein tails of chromosomes that get shortened with each cell division. When the telomere length reaches a critical point, cell senescence and death occur. Telomerase is a reverse transcriptase that counteracts telomere loss by adding telomeric sequences. In patients with acquired aplastic anemia, the mean telomere length (TRF) of peripheral blood leukocytes is generally short when compared to normal controls, without it being clear whether a relationship between TRF and disease severity exists. Additionally, increased telomerase activity (TA) is found in the bone marrow mononuclear cell population (MNCs) of aplastic anemia patients, especially in the chronic form of the disease. Fanconi anemia (FA) patients generally demonstrate increased TA and short telomeres in peripheral blood MNCs, a fact attributed to the high turnover of hematopoietic progenitor cells in combination with direct breakages at telomeric sequences. Furthermore, a strong correlation has been shown between TRF and the severity of aplastic anemia, but not with FA evolution towards myelodysplastic syndrome or acute myeloblastic leukemia. In respect of dyskeratosis congenita (DC), a disease of either X-linked or autosomal dominant/recessive inheritance which is characterized by premature ageing of highly regenerative tissues, studies have been carried out in order to elucidate whether the X-linked DC is caused by a defect in ribosomal RNA processing and/or telomere maintenance. Finally, the direct genetic link established between DC pathogenesis and short telomeres may lead to the development of new therapeutic protocols for diseases characterized by short telomere length and subsequent genomic instability.

Asplenia in a patient with Fanconi's anemia-like congenital aplastic anemia.

Fanconi's anemia (FA) is an autosomal recessive disease manifested by pancytopenia resulting from bone marrow failure, variable physical anomalies and cancer susceptibility. A seven-year-old girl with Fanconi's anemia-like congenital aplastic anemia and concurrent asplenia without the congenital heart defects or the abdominal heterotaxia is reported. Asplenia was indicated using denatured red cells labelled with 51Cr, abdominal ultrasonography and computerized tomography. Immunological studies showed immunoglobulins (IgG, IgA, IgM), C3 and C4 levels within normal limits and the percentage of CD3, and C4 cells and the CD4/CD8 ratio decreased. The patient had not been exposed to recurrent pneumococcal infections. We think that isolated asplenia may occur in patients with Fanconi's anemia-like congenital aplastic anemia without the congenital heart diseases or abdominal heterotaxia.

Allogeneic hematopoietic stem cell transplantation: current issues and future prospects.

Major developments have occurred in the field of hematopoietic stem cell transplantation since the first successful transplants from HLA-identical siblings in the late 60's. The formally experimental procedure has become established therapy for a number of congenital or acquired disorders of the hematopoietic system and for chemotherapy-sensitive malignancies. Reduced transplant-related mortality has led to a widening of indications. The present review summarizes current issues and future prospects in allogeneic stem cell transplantation. These issues and prospects will include; stem cell sources, alternative donors, graft-versus-host disease, indications and long-term survival following allogeneic stem cell transplantation.

[The use of GnRH agonists in severe uterine hemorrhages in adolescence caused by congenital aplastic and hypoplastic anemias]. / Izpolzuvane na GnRH-agonisti pri tezhki matochni kruvotecheniia v adolestsentnata vuzrast, prichineni ot vrodeni aplastichni i khipoplastichni anemii.

GnRH agonists, applied for a long period of time or as depot forms, lead to blocking of gonadotropin and ovarian steroid synthesis. We used their property to induce amenorrhea for treating menorrhagic and menometrorrhagic bleeding in adolescence caused by inborn aplastic and hypoplastic anaemia. In patients with uterine bleeding during the first regular menstrual period or recurring during menstrual periods Zoladex (depot GnRH agonist) has been applied, resulting in stop of bleeding in 2 to 4 days. The drug-induced amenorrhea provides the possibility for physiologic restoring of hemoglobin levels, improvement of therapeutic results from adjuvant antianaemic therapy. Thus a more favourable basis for treating of the main disorder is being created. When surgery is indicated, GnRH agonists provide the opportunity for planning of operating management or for laser ablation of endometrium.

Analysis of 65 Turkish patients with congenital aplastic anemia (Fanconi anemia and non-Fanconi anemia): Hacettepe experience.

During the last 14 years, 65 unrelated patients were diagnosed as having constitutional aplastic anemia (CAA). In 52 of 65 patients the diepoxybutane (DEB) test was positive. Comparison of several hematological and clinical parameters in Fanconi anemia (FA) (DEB+) and non-Fanconi anemia (non-FA)(DEB ) patients disclosed no statistically significant differences. The study indicated that in Turkey there were no peculiarities in associated congenital abnormalities in FA and non-FA. The rate of consanguinity was 78% in FA and 46% in non-FA, suggesting that also among the non-FA group recessively inherited disorders are hidden. The mean age at diagnosis in FA was 7.7+/-4.4 (1.8-12) and in non-FA 7.8+/-3.8 (2-15) years. Nine out of 52 FA and five out of 13 non-FA patients died during the follow-up period. Five of the 52 FA patients developed malignancies, three of them had acute myeloblastic leukemia (AML), one a squamous cell carcinoma of the gingiva, and another a hepatocellular carcinoma. Peliosis hepatica occurred in three of the FA and one of the non-FA patients. A total of seven patients stayed in remission without any medication. The remaining 58 patients were given 2-5 mg/kg of oxymetholone and 5 mg prednisolone treatment. Because of sustained remission, oxymetholone therapy was terminated in four of the 45 FA and two of the 13 non-FA patients. Detailed examination of the pedigrees of all of patients indicated the presence of multiple congenital anomalies. In seven of 52 FA and one of 13 non-FA patients there was increased risk for AML and/or other cancers among family members.

[Allogenic bone marrow transplantation for Fanconi's anemia with leukemic transformation from an HLA identical father].

We report a case of a 19-year-old male with congenital aplastic anemia and multiple abnormalities; short stature, hypoplastic thumb, skin pigmentation and mental retardation. He was admitted to our hospital because of severe pancytopenia. Bone marrow aspiration showed markedly hypocellular marrow with 42% myeloblasts. He was diagnosed as AML (M2) transformed from Fanconi's anemia and underwent allo-BMT from an HLA-identical father. The conditioning regimen consisted of high dose Ara-C, high dose etoposide and 12Gy fractionated total body irradiation. Severe toxicity associated with the conditioning regimen was not observed. Cyclosporin A and short-term methotrexate were administered for prophylaxis of acute GVHD. Neither acute nor chronic GVHD were observed. He is well and free of disease for 15 months since BMT. Very few cases of Fanconi's anemia with leukemic transformation treated by BMT have been reported. Long-term observation will be necessary to evaluate our conditioning regimen for Fanconi's anemia with leukemic transformation.

Aase-Smith syndrome: report of a new case with unusual features.

A new case of Aase-Smith syndrome has been reported with additional findings, including microcephaly, axial rotation of the kidneys, preaxial polydactyly and leukopenia. The patient had almost complete clinical remission with corticosteroid treatment. The findings in this case suggest that it is very difficult to differentiate Aase-Smith syndrome from Blackfan-Diamond and Fanconi's anemias as well as from those cases reported by Murphy and Lubin, and Jones and Thompson.

Severe idiopathic congenital aplastic anemia: role of hematopoietic growth factors.

A baby boy with constitutional aplastic anemia refractory to treatment with hematopoietic growth factors underwent BMT from an unrelated HLA-compatible donor. The BM failed to engraft but the combination of a conditioning regimen, immunosuppression and hematopoietic growth factors resulted in a recovery of the patient's own BM and a good outcome.

Aase syndrome: novel radiographic features.

We report on a female with hypoplastic anemia and abnormally digitalized thumbs who presented with growth failure and novel osseous radiologic abnormalities. In addition to thumb anomalies, abnormalities of the clavicles, ilia, distal sacrum, and coccyx and described.

Diamond-Blackfan syndrome and neutropenia.

Neutropenia is a rare complication of Diamond-Blackfan syndrome (congenital hypoplastic anaemia). Three patients are reported: all had neutropenia as well as anaemia, and to investigate the cause of the neutropenia culture of bone marrow for granulocyte-macrophage colony forming cells (GMCFCs) was performed. Two cases had a low incidence of GMCFCs, but the third case had a high incidence. These findings suggest that myeloid precursors can be abnormal in Diamond-Blackfan syndrome and that the mechanism of neutropenia may, like that of anaemia, vary from patient to patient.