Ph-positive CML in blastic phase with monosomy 7 in a Down syndrome patient. Monitoring by interphase cytogenetics and demonstration of maternal allelic loss

Chronic myeloid leukaemia with pulmonary leucostasis in a young Down syndrome patient

We reported a rare case of chronic myeloid leukaemia (CML) complicated with pulmonary leucostasis in an 11-year-old Down syndrome (DS) patient who presented with respiratory distress. His peripheral blood investigation showed features of CML with 17% circulating blast, with immunophenotyping showing positivity towards myeloid markers. Peripheral blood polymerase chain reaction for BCR–ABL fusion transcripts was positive, and cytogenetic studies showed Ph chromosome with trisomy 21. Despite cytoreduction therapy with hydroxyurea and leukapheresis, the patient succumbed due to shock, with multiple organ failure. Our case highlights the need for early detection and rapid referral for aggressive treatment in DS patients with CML, as the combination is associated with a poor outcome.

Shwachman syndrome as mutator phenotype responsible for myeloid dysplasia/neoplasia through karyotype instability and chromosomes 7 and 20 anomalies

An investigation of 14 patients with Shwachman syndrome (SS), using standard and molecular cytogenetic methods and molecular genetic techniques, showed that (1) the i(7)(q10) is not, or not always, an isochromosome but may arise from a more complex mechanism, retaining part of the short arm; (2) the i(7)(q10) has no preferential parental origin; (3) clonal chromosome changes, such as chromosome 7 anomalies and del(20)(q11), may be present in the bone marrow (BM) for a long time without progressing to myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML); (4) the del(20)(q11) involves the minimal region of deletion typical of MDS/AML; (5) the rate of chromosome breaks is not significantly higher than in controls, from which it is concluded that SS should not be considered a breakage syndrome; (6) a specific kind of karyotype instability is present in SS, with chromosome changes possibly found in single cells or small clones, often affecting chromosomes 7 and 20, in the BM. Hence, we have confirmed our previous hypothesis that the SS mutation itself implies a mutator effect that is responsible for MDS/AML through these specific chromosome anomalies. This conclusion supports the practice of including cytogenetic monitoring in the follow-up of SS patients.

Familial myelodysplastic syndromes, monosomy 7/trisomy 8, and mutator effects

A family is reported, in which two sisters presented with myelodysplastic syndrome (MDS), namely refractory anemia with excess of blasts in transformation (RAEB-t), and refractory anemia (RA). Bone marrow chromosome changes were present in both: trisomy and tetrasomy 8 (with a pericentric inversion of one chromosome 8) in the older sister, and monosomy 7 (with clones with additional trisomies 19 and 21) in the younger one. Molecular data were obtained on the parental chromosome involved in these numerical anomalies, which proved to be of paternal origin in these cases. The observations of this family, and a review of familial cases of MDS/acute myeloid leukemia (AML), led us to consider that they may be divided into two groups: those which arise on the basis of a Mendelian predisposing disorder exerting a mutator effect, often with the acquisition of monosomy 7, and those in which no specific Mendelian predisposing disease is recognized, as the familial monosomy 7 cases and the one reported here. We postulate that in these families an inherited mutator effect is present and that it causes a karyotype instability, which leads to MDS/AML, often through the acquisition of monosomy 7 and trisomy 8.

Familial platelet disorder with propensity to acute myelogenous leukemia: Genetic heterogeneity and progression to leukemia via acquisition of clonal chromosome anomalies

Familial platelet disorder with propensity to acute myelogenous leukemia, or FPD/AML (OMIM #601399), is a rare autosomal dominant condition, with only 12 families reported. It is characterized by qualitative and quantitative platelet defects and predisposition to the development of myeloid malignancies. Causal mutations have been identified in the RUNX1 gene (also known as AML1, CBFA2) in the 11 families so far analyzed. RUNX1 is a gene frequently involved in the pathogenesis of sporadic leukemia and myelodysplastic syndromes, through acquired chromosome rearrangements and point mutations. We report an Italian family with three members affected with FPD/AML, two sibs and their father, who developed myelodysplastic syndromes (which in one subsequently evolved into AML). Direct sequencing and polymorphisms haplotype analysis of the region of chromosome 21 where RUNX1 is mapped demonstrated that FPD/AML in this family was not caused by any mutation of the RUNX1 gene, thus providing evidence for the genetic heterogeneity of this disorder. Cytogenetic studies showed monosomy 7 in the marrow of all the three affected subjects, as well as an independent clone with trisomy 8 in the father. The importance of mutator effects in the pathogenesis of familial myeloid malignancies characterized by relevant chromosome changes, in the presence or absence of an underlying Mendelian disorder, has already been suggested. Our results and a review of the cytogenetic literature led us to postulate that mutations also causing FPD/AML may have a mutator effect that could give origin to myelodysplastic syndromes and acute myeloid leukemias through acquired chromosome changes.

Paternal isodisomy 7q secondary to monosomy 7 at recurrence in a Down syndrome child with acute myelogenous leukemia

We report a boy with Down syndrome and leukemia who acquired uniparental isodisomy of chromosome 7q as a secondary chromosomal change during recurrence of the disease. His karyotype before therapy was 46,XY,der(1)t(1;1)(p36;q32),-7,+21c/46,idem,del(9)(p22), whereas at recurrence it was 46,XY,der(1)t(1;1)(p36;q32,-7,der(7)(qter-->p22 through pter::q10-->qter),del(9)(p22),+21c/47,XY,+21c. By using polymerase chain reaction amplification of D7S493 and D7S527 markers, we identified the loss of the maternal chromosome 7 with a consequent paternal isodisomy in the clone with dup7q. This rearrangement could be implicated in the progression of the disease by causing (1) nullisomy for a gene or genes located on 7p22-->pter, (2) functional double doses of exclusively paternal expressed genes, and (3) restoration of the effects produced by haploinsufficiency of biparental expressed genes.

Pattern of malignant disorders in individuals with Down's syndrome

The pattern of occurrence of malignant disorders in people with Down's syndrome (DS) is unique and may serve as a model in the search for leukaemogenic genes and tumour suppressor genes on chromosome 21, since the risk of leukaemia is higher in individuals with DS than in non-DS individuals. Acute lymphoblastic leukaemia in DS shares many of the clinical characteristics of the same malignancy in other patients, and with current intensive therapy the long-term survival is similar. Myelodysplastic syndrome and acute myeloid leukaemia have unique clinical characteristics in these patients and are best described as a single disorder, termed myeloid leukaemia of DS. When these patients are treated intensively, they show better survival rates than patients without DS. This may be related to increased expression of genes on chromosome 21 contributing to increased chemosensitivity. Chronic myeloid leukaemia and chronic lymphocytic leukaemia occur less often than expected. With the exception of an increased risk of retinoblastoma, germ-cell tumours, and perhaps lymphomas, the risk of developing solid tumours is lower in both children and adults. Breast cancer is almost absent, and the risk of a second malignant disease after treatment for leukaemia also appears to be decreased. Increased susceptibility to apoptosis in DS may result in cell death rather than malignant transformation after major cell injuries. This hypothesis would explain the decreased risk of both solid tumours and secondary cancers.

Familial partial monosomy 7 and myelodysplasia: different parental origin of the monosomy 7 suggests action of a mutator gene

Two sisters are reported, both with a myelodysplastic syndrome (MDS) associated with partial monosomy 7. A trisomy 8 was also present in one of them, who later developed an acute myeloid leukemia (AML) of the M0 FAB-type and died, whereas the other died with no evolution into AML. Besides FISH studies, microsatellite analysis was performed on both sisters to gather information on the parental origin of the chromosome 7 involved in partial monosomy and of the extra chromosome 8. The chromosomes 7 involved were of different parental origin in the two sisters, thus confirming that familial monosomy 7 is not explained by a germ-line mutation of a putative tumor-suppressor gene. Similar results were obtained in two other families out of the 12 reported in the literature. Noteworthy is the association with a mendelian disease in 3 out of 12 monosomy 7 families, which suggest that a mutator gene, capable of inducing both karyotype instability and a mendelian disorder, might act to induce chromosome 7 anomalies in the marrow. We postulate that, in fact, an inherited mutation in any of a group of mutator genes causes familial monosomy 7 also in the absence of a recognized mendelian disease, and that marrow chromosome 7 anomalies, in turn, lead to MDS/AML.

A novel BCR-ABL transcript e2a2 in a chronic myelogenous leukaemia patient with a duplicated Ph-chromosome and monosomy 7

A novel BCR-ABL transcript was detected by multiplex RT-PCR in a patient with Philadelphia chromosome (Ph) positive chronic myelogenous leukaemia (CML) in accelerated phase. Sequencing of the aberrant transcript revealed an in-frame e2a2 fusion that included a 9 basepairs insertion. Cytogenetic analysis showed t(9;22), an additional Ph chromosome and monosomy 7. The clinical course was dismal: therapy was poorly tolerated, and the patient died in blast crisis 10 months after diagnosis. These data support the association of additional Ph and monosomy 7 with poor prognosis and suggest that the novel e2a2 BCR-ABL transcript may be related to an aggressive clinical course.

Transient monosomy 7: a case series in children and review of the literature

BACKGROUND

Monosomy 7 and deletions of the long arm of chromosome 7 [del (7q)] are recurrent, nonrandom chromosomal abnormalities associated with both de novo and therapy-related myelodysplastic syndromes (MDS). The overall prognosis for children and adults with these chromosomal abnormalities is poor. In the current report, the authors present five children with MDS associated with monosomy 7/del(7q) who achieved spontaneous hematologic disease remission as well as a review of the literature.

METHODS

Five children with either de novo or treatment-related MDS who achieved spontaneous hematologic disease remission are presented. Relevant clinical, cytogenetic, and fluorescent in situ hybridization data are included.

RESULTS

All patients were boys. Three had de novo MDS whereas two others previously had received chemotherapy for another malignancy. Four patients achieved spontaneous and durable hematologic disease remission that was associated with cytogenetic disease remission in all three patients tested. The fifth patient developed a disease recurrence and died with evidence of clonal evolution after a long interval of hematologic and cytogenetic remission.

CONCLUSIONS

A subset of children who develop MDS associated with monosomy 7 or del(7q) achieve spontaneous hematologic and cytogenetic improvement. Although this appears to be uncommon, further data are needed to determine the percentage of patients who improve without therapy and to define clinical characteristics that may predict this clinical outcome. These findings suggest that monosomy 7/del(7q) is insufficient to produce full leukemic transformation.