Bone marrow monosomy 7: hematologic and clinical manifestations in childhood and adolescence

An abnormal clone with monosomy 7 and trisomy 21 in the bone marrow of a child with congenital agranulocytosis (Kostmann disease) treated with granulocyte colony-stimulating factor. Evolution towards myelodysplastic syndrome and acute basophilic leukemia

Cytogenetic analysis of bone marrow cells revealed an abnormal clone with monosomy 7 and trisomy 21 in a 12-year-old child with Kostmann disease (KD). The patient presented with anemia, thrombocytopenia, and splenomegaly after 5 years of treatment with granulocyte colony-stimulating factor (G-CSF). The bone marrow morphology was consistent with the diagnosis of myelodysplastic syndrome (MDS). Administration of G-CSF was discontinued at this point. Bone marrow studies 2 and 5 months later showed persistence of both myelodysplasia and the abnormal clone with monosomy 7 and trisomy 21. Monosomy 7 was also confirmed by fluorescence in situ hybridization (FISH). After 2 months of follow-up, the patient presented with acute basophilic leukemia, a very rare variant of acute myeloid leukemia (AML), expressing the same bone marrow chromosome abnormalities as observed earlier. This is a rare case of KD with prolonged survival and a cytogenetically abnormal clone evolving to MDS and acute basophilic leukemia. The significance of monosomy 7 and trisomy 21 in KD treated with G-CSF is discussed.

Molecular evidence that childhood monosomy 7 syndrome is distinct from juvenile chronic myelogenous leukemia and other childhood myeloproliferative disorders

The observation that juvenile chronic myelogenous leukemia (JCML) and childhood bone marrow monosomy 7 syndrome (Mo 7) are similar in many clinical and epidemiologic respects suggests a shared pathogenic basis and raises the possibility that the bone marrows of patients with JCML might lose chromosome 7 alleles by mechanisms that do not result in detectable cytogenetic deletions. We used a series of polymorphic markers mapped to chromosome 7 to test this hypothesis in 22 children with MPS and MDS, including 19 with JCML. All MPS and MDS samples demonstrated allelic heterozygosity with at least one chromosome 7 marker; 16 were heterozygous with probes from both 7p and 7q. Furthermore, the percentage of patient bone marrow samples heterozygous at each locus tested was similar to the frequency observed in the normal population. Whereas these data demonstrate that submicroscopic loss of large segments of chromosome 7 alleles is uncommon in children with MPS and MDS who do not have Mo 7, they do not exclude small deletions around an uncharacterized tumor-suppressor locus. Our results suggest that a number of distinct molecular events contribute to leukemogenesis, and we propose a multistep model to explain the similarities and differences between the major subtypes of childhood MPS and MDS.

Platelet storage pool deficiency, leukemia, and myelodysplastic syndromes

Abnormalities in platelet dense granules, small intracellular organelles containing ATP, ADP, calcium, serotonin, and pyrophosphate, have frequently been reported in patients with leukemia and myeloproliferative disorders, particularly acute and chronic myelogenous leukemia. Recent studies of a family which includes several members with an autosomal dominant dense granule deficiency condition show an association between the presence of this form of dense granule deficiency and the development of acute myelogenous leukemia. Studies in two additional patients, one with the Monosomy 7 syndrome and the second with a myelodysplastic syndrome, revealed a defect in platelet dense granules. This defect appears to be due to an abnormality in the formation of these granules rather than the presence of empty vesicular structures or decreased contents due to activation associated secretion. The results suggest that the defect in platelet dense granules associated with leukemia or myelodysplastic syndromes may result from a chromosome alteration in the megakaryocyte cell line leading to decreased formation of dense granules. Studies in the family with an inherited bleeding disorder suggest that a gene coding for a protein important for the formation of dense granules is located adjacent to a gene which, when abnormal, may predispose to the development of leukemia.

Monosomy 7 syndrome. Clinical heterogeneity in children and adolescents

Bone marrow monosomy 7 is the most frequent karyotypic abnormality found in patients with chronic myeloproliferative disorders. To a review of 46 previously reported pediatric patients we add three additional cases. Clinical presentation is usually dependent upon which cell lines are most perturbed in this pluripotent stem cell disorder. Sixteen (35%) children presented by their first birthday and 35 (76%) by their sixth birthday. Distinctive differences in presentation exist between infants, children, and adolescents. Younger patients were more symptomatic and had greater degree of hepatosplenomegaly and leukocytosis. The prognosis is very poor and death usually occurs within two years from complications attributable to cytopenias, cellular dysfunction, or transformation to acute nonlymphocytic leukemia. Implications for therapy are discussed.

Clonal chromosomal abnormalities showing multiple-cell-lineage involvement in acute myeloid leukemia

To determine whether one or more hematopoietic-cell lineages are involved in acute myeloid leukemia (AML), we designed a technique that simultaneously identifies a cell as malignant and determines its lineage. We used numerical clonal chromosomal abnormalities, which are readily detected, to indicate neoplasia, and monoclonal antibodies in an alkaline phosphatase-antialkaline phosphatase detection procedure to identify lineages as granulocytic-monocytic, erythrocytic, or megakaryocytic. Examination of bone marrow from 12 patients with AML showed metaphases of granulocytic-monocytic lineage with abnormal karyotypes in all patients. In seven patients, we also detected abnormal karyotypes in the erythrocytic or megakaryocytic lineage. In all four patients with monosomy 7, both granulocytic-monocytic and erythrocytic cells were affected. Two of four patients with trisomy 8 also had evidence of multiple-lineage involvement, but in two the erythrocytic lineage had normal karyotypes, suggesting an origin at a progenitor-cell stage committed to granulocytic-monocytic development. Multiple-lineage involvement was found in AML both arising de novo (four of five analyzable cases) and following another cancer (three of four analyzable cases). These data demonstrate multiple-lineage involvement in a high proportion of cases of AML and suggest that many cases originate from the multipotent hematopoietic cell or from an earlier progenitor cell.

Childhood monosomy 7 revisited

Monosomy 7 is found in acute myeloid leukaemia (AML) and myelodysplasia and is characteristic of a rare chronic myeloproliferative disease (MPD) of young children. We have seen 16 children with monosomy 7. Their clinical features and response to treatment are discussed. Monosomy 7 diseases appear to have a particularly poor prognosis. The AML is often resistant to treatment and relapse is common. Children with chronic MPD die of bone marrow failure or evolve to AML or myelofibrosis. We have treated these children intensively with combination chemotherapy and allogeneic bone marrow transplantation. Four children with MPD received supportive care and low dose chemotherapy alone. They all died, surviving between 4 months and 4 years. Six children with MPD received intensive chemotherapy: three remitted, one relapsing after 9 months, the others remaining in remission at 18 months and 3 years. One child with MPD has undergone successful BMT and survives 7 1/2 years after presentation. Remission was achieved in three of four cases of AML. They all relapsed within 9 months. Bone marrow transplantation was successful in one child with myelofibrosis. Intensive chemotherapy and early bone marrow transplantation is likely to offer these children their best chance of survival.

Familial myelodysplasia: progressive disease associated with emergency of monosomy 7

Two brothers developed hypoplastic anaemia with the development in one of refractory anaemia with excess blasts (RAEB) accompanied by emergence of monosomy 7. Both brothers have a constitutional inversion of chromosome 1. Neither shows the increased chromosomal fragility of Fanconi's anaemia or its variants. This family is the third reported in which monosomy 7 has been found when leukaemic or preleukaemic transformation has occurred in patients with familial hypoplastic anaemia.

Simple monosomy 7 and myelodysplastic syndrome in thirteen patients without previous cytostatic treatment

Thirteen patients with simple monosomy 7 presented with pallor in 11, easy bruisability in five, splenomegaly in four, no infections, refractory anaemia in all, granulocytopenia in seven, monocytosis in three, leucocytosis in four and thrombocytopenia in eight. Peripheral blood and bone marrow findings were consistent with myelodysplastic syndrome (MDS) type I in three, type II in two, type III in two, type IV in three and acute myelofibrosis in three patients. Transformations to acute leukaemia in seven patients were M2 in one, M4 in four, megakaryoblastic in one and undifferentiated in one. Lack of chromosome 7 in 12-85% of analysed cells at initial presentation of MDS progressed to nearly 100% during blastic transformation. At that time an additional change in the long arm of chromosome 3 was seen in two patients and trisomy 8 in 6% of analysed cells in a third case. The median survival time was 12 months for MDS and 3 months for acute leukaemia. Simple monosomy 7 appears to be largely confined to young children and elderly people.

Chromosomal changes in secondary leukemias of childhood and young adulthood

The increasing success of antineoplastic therapy has resulted in a growing number of long-term survivors. These people are at risk for complications of the therapy itself. Among these induced acute nonlymphoid leukemia (ANLL) has been both common and often lethal. We reviewed 72 recently reported patients under 30 years of age at the time of initial diagnosis who developed a secondary, karyotypically defined leukemia. Fifty-eight patients contracted ANLL a mean of 4 1/2 years from the initial diagnosis. In 25 patients, this was preceded by a preleukemic phase characterized by a hypercellular bone marrow with abnormal precursors, often accompanied by peripheral pancytopenia, that lasted a mean of 6 months. Three additional patients died in this preleukemic phase. In all 61, the most common chromosomal abnormalities were numerical errors. Twenty-four patients had a hypodiploid karyotype, most often in those in whom the primary diagnosis was lymphoma (22 of 43). The most common chromosomes missing in whole or in part were number 7 (18 patients), number 5 (8 patients), number 17 (5 patients), and number 21 (4 patients). The anomalies were frequently multiple and complex. Monosomy 7 figured particularly strongly and may be similar to a karyotypically identical myeloproliferative disorder characterized by micromegakaryocytes, giant platelets, and abnormal granulocyte function arising de novo in children. These findings are similar to those in older patients with ANLL induced by environmental carcinogens or antineoplastic therapy. They are different from the karyotypic changes seen in de novo ANLL in children and young adults, suggesting a different etiology. Also, they reinforce the need to find less leukemogenic treatment programs.