Preleukaemic states in children

Ecological variables for developing a global deep-ocean monitoring and conservation strategy

The deep sea (>200 m depth) encompasses >95% of the world's ocean volume and represents the largest and least explored biome on Earth (<0.0001% of ocean surface), yet is increasingly under threat from multiple direct and indirect anthropogenic pressures. Our ability to preserve both benthic and pelagic deep-sea ecosystems depends upon effective ecosystem-based management strategies and monitoring based on widely agreed deep-sea ecological variables. Here, we identify a set of deep-sea essential ecological variables among five scientific areas of the deep ocean: (1) biodiversity; (2) ecosystem functions; (3) impacts and risk assessment; (4) climate change, adaptation and evolution; and (5) ecosystem conservation. Conducting an expert elicitation (1,155 deep-sea scientists consulted and 112 respondents), our analysis indicates a wide consensus amongst deep-sea experts that monitoring should prioritize large organisms (that is, macro- and megafauna) living in deep waters and in benthic habitats, whereas monitoring of ecosystem functioning should focus on trophic structure and biomass production. Habitat degradation and recovery rates are identified as crucial features for monitoring deep-sea ecosystem health, while global climate change will likely shift bathymetric distributions and cause local extinction in deep-sea species. Finally, deep-sea conservation efforts should focus primarily on vulnerable marine ecosystems and habitat-forming species. Deep-sea observation efforts that prioritize these variables will help to support the implementation of effective management strategies on a global scale.

Retinoblastoma in association with the chromosome breakage syndromes Fanconi's anaemia and Bloom's syndrome: clinical and cytogenetic findings

Two children presenting with sporadic unilateral retinoblastoma and exhibiting a high degree of chromosome breakage were noted to have unusual facies, microcephaly and abnormal skin pigmentation. In the first child the pattern of both spontaneous and mitomycin-C-induced chromosome breakage was characteristic of Fanconi's anaemia although the degree of breakage was extreme. She also exhibited a striking increase in X-ray-induced chromosomal damage in G0 lymphocytes as measured by dicentric formation and increase in chromatid-type aberrations. She had a number of typical clinical features, including cafe-au-lait patches and abnormalities involving the kidney; however, she demonstrated neither the hypoplasia of radius and thumb nor the typical aplastic phase of this disorder. At age 22 months the child became anaemic with trilineage myelodysplasia, which was rapidly followed by the development of acute myeloblastic leukaemia. The early onset (at age 4 months) of retinoblastoma may have been associated with the underlying genomic instability. The second child exhibited a pattern of chromosome breakage characteristic of Bloom's syndrome, in addition to a moderate increase in damage induced by mytomycin-C. She had the typical stunted growth and malar hypoplasia of Bloom's syndrome although she did not demonstrate the frequently described erythematous 'butterfly rash' Although patients with Fanconi's anaemia and Bloom's syndrome are recognised to be at an increased risk of cancer, retinoblastoma has not previously been described in patients with either condition. We suggest that underlying recessive chromosome breakage syndromes may be underdiagnosed in paediatric cancer patients, with important implications for prognosis and genetic counselling.

Myelodysplastic syndromes in childhood: description of seven cases

Seven children with a primary myelodysplastic syndrome were seen at our center over a 9-year period. Two presented with refractory anemia, three with refractory anemia with excess of blasts, and two with refractory anemia with excess of blasts in transformation. All children received supportive therapy, including blood transfusions in five of them. Three patients developed acute myeloid leukemia and were treated with intensive chemotherapy, followed by allogeneic or autologous marrow transplantation in the two responders. All three died of either infection or progressive disease. The other four patients are still alive a median of 71 months (range 38-130) after diagnosis. These results confirm the difficulties in managing patients with myelodysplastic syndromes.

Primary myelodysplastic syndrome in children: the clinical experience in 33 cases

We describe the clinicomorphological features in 33 cases of primary myelodysplastic syndrome classified according to the FAB classification which presented to a single centre over a 12 year period. Presenting features were typically related to pancytopenia although hepatosplenomegaly and granulocytic sarcomas were far more prevalent than in the adult population. Morphological assessment of the peripheral blood and the bone marrow showed seven patients had refractory anaemia (RA), 13 patients had RA with excess of blasts (RAEB), nine patients had RAEB in transformation (RAEB-t) and four patients had chronic myelomonocytic leukaemia (CMML). The overall mean survival was short (9.9 months) in all the subgroups and the leukaemic transformation rate was high. None of the patients scored 0-1 according to the Bournemouth Scoring System; four patients scored 2 whereas 29 patients scored 3 to 4. We conclude that unlike adults, the myelodysplastic syndromes in children run an aggressive clinical course, irrespective of the FAB subtype, and the pathogenesis of these diseases in paediatric practice warrants scientific scrutiny. Intensive chemotherapy such as the one used in de novo-AML lead to complete remission in some children and these early results suggest that this should be the treatment of choice in paediatric MDS.

Myelodysplastic syndromes in childhood: a population based study of nine cases

Nine cases of de novo myelodysplastic syndromes (MDS) in childhood from a population based study are presented. The annual incidence of MDS was 3.4/1,000,000 in children less than 15 years old, corresponding to 8.7% of all haematological malignancies in childhood. Two patients had Down's syndrome. None of the remaining patients had constitutional anomalies. All patients were classified according to the FAB classification. Five patients presented with refractory anaemia (RA), only one of these did not progress, one showed clonal evolution, and the remaining three patients all progressed to refractory anaemia with excess of blasts (RAEB). Three patients presented with RAEB. Two progressed to overt leukaemia. The last patient was classified as chronic myelomonocytic leukaemia (CMML). Clonal cytogenetic abnormalities were detected in five patients, in three of them as monosomy 7. Five patients have died; two of progressive disease, two of infections, and one of haemorrhage, two of the latter three patients died during therapy induced cytopenia. Of the four patients still alive, one patient showed a complete remission after cyclosporine and later immunoglobulin therapy, one patient is a long-term survivor after allogeneic bone marrow transplantation, and one patient apparently obtained a spontaneous remission several months after chemotherapy.

Myelodysplastic syndrome with trisomy 8 in an adolescent with Fanconi anaemia and selective IgA deficiency

We describe a patient with growth failure and multiple congenital anomalies characteristic of Fanconi anaemia, but without the classical feature of progressive bone marrow hypoplasia. Following treatment with growth hormone for a period of 8 years, he presented with myelodysplastic syndrome and a karyotypically abnormal clone in the bone marrow (47,XY,+8). The diagnosis of Fanconi anaemia was supported by the induction of abnormally high levels of characteristic chromosome aberrations in peripheral lymphocytes following exposure in vitro to the bifunctional alkylating agent mitomycin C. Immune function studies also identified a selective IgA deficiency. The relative importance of interacting constitutional and exogenous factors involved in the development of preleukaemia in this patient is discussed.

Acute myelogenous leukaemia in children

Acute myelogenous leukaemia in childhood is considerably more resistant to chemotherapy than the acute lymphocytic leukaemias. Recently, more aggressive therapy has improved the outlook for children with this difficult form of leukaemia. Long-term disease-free survival of children achieving remission has been reported to be more than 40% in some studies. This paper reviews both the present concept of leukaemogenesis as well as some of the more recent therapeutic studies on childhood AML.

Preleukemic syndromes and other syndromes predisposing to leukemia

The myelodysplastic and myeloproliferative syndromes are syndromes in childhood that may precede leukemia. Clinical and biologic features are reviewed in this article. Although rare, they offer an unique opportunity to observe the evolution of leukemia and give clues that are helping us to understand the leukemogenic process.

Myelodysplastic syndromes: their history, evolution and relation to acute myeloid leukaemia

The myelodysplastic syndromes (MDS) constitute a heterogeneous group of clonal disorders arising from a multipotent haemopoietic progenitor which share a leukaemic propensity, 30% of cases culminating in acute myeloid leukaemia (AML). Their pathogenesis probably entails multiple steps, phenotypic progression being determined by either expansion or evolution of the abnormal clone. The clonal origin of certain cases of de novo AML is analogous to that of MDS and evidence that they share a common pathogenesis and distinct biological characteristics is beginning to emerge.