Myelodysplastic Syndrome in Children Charlotte M. Niemeyer

Contents

7.1 Introduction . . . . 81

7.2 Classification of Childhood MDS . . . . . 81

7.3 Cytogenetics . . . . 82

7.4 Primary MDS . . . . 83

7.4.1 Primary MDS Without Increase in Blast Count (Refractory Cytopenia [RC]) . . 83

7.4.2 Primary MDS with Increased Blasts (RAEB and RAEBt) . . . . 84

7.5 Secondary MDS . . . . 85

7.5.1 MDS in Congenital Bone Marrow Failure . . . . 85

7.5.2 MDS After Acquired Aplastic Anemia 85 7.5.3 Familial MDS . . . . 86

7.5.4 Therapy-related MDS . . . . 86

Summary . . . . 86

References . . . . 86

7.1 Introduction

Myelodysplastic syndrome (MDS) is much rarer in chil- dren than in adults, accounting for less than 5% of hem- atopoietic neoplasia in childhood. Population-based data suggest an annual incidence of 1±2/million (Hasle et al.

1995, 1999b; Passmore et al. 2003). There are significant differences in presentation, underlying cytogenetic ab- normalities, and classification between MDS in children and adults. The therapeutic aim in children with MDS is a

cure, and therapeutic efforts concentrate on hematopoie- tic stem cell transplantation (HSCT) rather than on novel therapeutics such as anti-angiogenic therapy, farnesyl transferase, or DNA methylation inhibitors.

7.2 Classification of Childhood MDS

MDS in childhood is a very heterogeneous group of dis- orders associated with a variety of different clinical con- ditions. This diversity hampered a generally accepted classification in the past. Although some investigators have argued that childhood MDS can be classified ac- cording to the French-American-British (FAB) nomen- clature in the same subgroups as adult cases (Brandwein et al. 1990; Hasle et al. 1995, 1999b; Passmore et al.

2003), others pointed out the system was rarely used in practice (Bader-Meunier et al. 1996; Luna-Fineman et al. 1999). In addition, an infantile monosomy 7 syn- drome characterized by male predominance, hepato- splenomegaly, and leukocytosis had been included as a separate entity in the classification of childhood MDS (Passmore et al. 1995). Because complete loss of chromosome 7 occurs in all morphologic MDS sub- groups (Hasle et al. 1999a) and there is no evidence that monosomy 7 represents a discrete entity, it should no longer be referred to as the monosomy 7 syndrome (Hasle et al. 1999a; Woods et al. 2002).

Similar to the FAB classification, the recent World Health Organization (WHO) classification of neoplastic diseases of the hematopoietic and lymphoid tissues (Jaffe et al. 2001) is based on a review of adult cases.

It recognizes juvenile myelomonocytic leukemia

(JMML) as a distinct entity, but the subdivision of

Charlotte M. Niemeyer

MDS does not reflect the hematological and clinical pic- ture of MDS in childhood. To account for the special features of MDS in children, an international consensus on a pediatric modification of the WHO classification has been proposed (Table 7.1) (Hasle et al. 2003). Myelo- dysplastic and myeloproliferative disorders in children are separated into three main groups: JMML, MDS, and Down syndrome. JMML is a unique disorder of in- fancy characterized by a hyperactive RAS signaling pathway due to molecular aberrations in the genes en- coding for SHP-2, RAS, or neurofibromatosis type 1.

MDS in Down syndrome in the first 5 years of life is not biologically different from AML in these patients.

The unifying term ªmyeloid leukemia of Down Syn- dromeº is proposed for this disorder, and patients should be excluded from MDS series.

Childhood MDS, arising de novo or secondary to a predisposing condition, is subdivided into refractory cytopenia (RC), refractory anemia with excess blasts (RAEB), and refractory anemia with excess blasts in transformation (RAEBt) (Hasle et al. 2003). The term ªRCº rather than ªrefractory anemia (RA)º was chosen because thrombocytopenia and neutropenia are more frequently observed than anemia (Kardos et al. 2003).

In childhood MDS, RC with ringed sideroblasts is infre- quently found, the unique 5q± syndrome has not been described, and the importance of multilineage dysplasia

in RA is unknown. Consequently, these adult subtypes were omitted from the pediatric WHO modification.

For the definition of MDS, the WHO classification eliminated RAEBt (Jaffe et al. 2001). Because there are no data indicating whether a blast threshold of 20% is better than the traditional 30% to distinguish MDS from de novo AML in children, the International Consortium suggested retaining the subtype of RAEBt with 20±30%

blasts in the bone marrow until more data are available.

It should be emphasized, however, that the blast count is insufficient to differentiate de novo AML from MDS (see below).

MDS after prior chemo- or radiation therapy, prior acquired aplastic anemia, in congenital bone marrow failure disorders, and in familial disease are classified as secondary MDS (Hasle et al. 2003). All other cases are named primary MDS, although it is reasonable to assume that most of these disorders are secondary to some yet unknown genetic predisposition. These pre- sumed underlying genetic changes may also give rise to subtle phenotypic abnormalities observed in many children with primary MDS.

The Toronto group suggested a descriptive CCC classification schema in which the first C stands for ªcat- egory of underlying disease,º the second C for ªcytol- ogy,º and the third C for ªcytogeneticsº (Mandel et al.

2002). Cytology is used to subdivide both RC and RAEB into three subgroups based upon level of dysplasia. The CCC classification emphasizes the importance of under- lying pathogenetic factors because they may determine treatment preferences. However, due to an infinite num- ber of possible subgroups, the CCC system will be diffi- cult to use in clinical practice. Although there is no per- fect system for classifying pediatric MDS, lumping as proposed in the modified WHO approach may be more appropriate for classification and clinical studies than splitting as proposed in the CCC system.

7.3 Cytogenetics

The frequency of an abnormal karyotype in hemato- poietic cells varies among subtypes of MDS in child- hood (Table 7.2). In advanced primary MDS, about 60% of children have chromosomal aberrations (Groupe Francais de Cytogenetique Hematologique 1997; Luna-Fineman et al. 1999). In contrast to AML, nu- merical abnormalities dominate; structural abnormali- ties are frequently part of a complex karyotype with nu- 82

Table 7.1. Classification of MDS and myelodysplastic//

myeloproliferative disorders of childhood I. Myelodysplastic/myeloproliferative disease

Juvenile myelomonocytic leukemia (JMML)

Chronic myelomonocytic leukemia (CMML) (secondary only)

BCR-ABL-negative chronic myeloid leukemia (Ph-CML) II. Down syndrome disease

Transient abnormal myelopoiesis (TAM) Myeloid leukemia of Down syndrome III. Myelodysplastic syndrome (MDS)

Refractory cytopenia (RC) (PB blasts <2% and BM blasts

<5%)

Refractory anemia with excess blasts (RAEB) (PB blasts 2±19% or BM blasts 5±19%)

RAEB in transformation (RAEBt) (PB or BM blasts

20±29%)

meric aberrations. Monosomy 7 is the most common cytogenetic abnormality being identified in approxi- mately 25% of cases. In the absence of standard banding cytogenetics, in situ hybridization (FISH) for identifica- tion in monosomy 7 is helpful (Ketterling et al. 2002), although the importance of small clones (<30%) of monosomy 7 cells remains unknown. Constitutional trisomy 8 mosaicism may remain unrecognized and should be tested for when trisomy 8 is found in the bone marrow.

Monosomy 7 is associated with a shorter time to progression in RC of childhood (Kardos et al. 2003).

In advanced MDS, monosomy 7 as the sole cytogenetic aberration has not been an unfavorable feature in most studies (Hasle et al. 1999a; Woods et al. 2002), in con- trast to findings in adults. Favorable cytogenetic aberra- tions, ±Y, 20q± and 5q±, have been reported in adults, but these aberrations are so infrequent in children that they are of no practical importance. AML-specific trans- locations, including t(8;21)(q22;q22), t(15;17)(q22;q12), or inv(16)(p13q22), may occur in cases of de novo AML with a low blast cell count. Their response to ther- apy is favorable, and they should not be considered MDS (Chan et al. 1997). In an ongoing prospective trial of the European Working Group of MDS in Childhood (EWOG-MDS) (Rogge and Niemeyer 2000), the distri- bution of karyotypes in advanced MDS shows normal cytogenetics in hematopoietic cells in 40% of patients, while 9% have three or more aberrations (complex kar- yotype) (Table 7.2). In contrast, only 18% of children with MDS secondary to chemo- or radiation therapy display a normal karyotype, while a complex karyotype is noted in 36%.

7.4 Primary MDS

In primary MDS the main diagnostic challenges are to differentiate low-grade MDS from aplastic anemia or congenital bone marrow failure syndromes, and high- grade MDS from AML.

7.4.1 Primary MDS Without Increase in Blast Count (Refractory Cytopenia [RC])

MDS with less than 5% blasts in the bone marrow is particularly difficult to diagnose because dysplasia of hematopoietic cells occurs frequently in children with a variety of disease states. In the absence of a cytoge- netic marker, the clinical course will have to be carefully evaluated before a diagnosis of RC can be established.

Minimal diagnostic criteria for pediatric MDS have been proposed by an International Consortium (Hasle et al. 2003). At least two of the following criteria must be fulfilled: sustained unexplained cytopenia, at least bi- lineage morphologic dysplasia, acquired clonal cytoge- netic abnormality, and increased myeloblasts (³5% in bone marrow) (Hasle et al. 2003). RC is the most com- mon subtype of childhood MDS, accounting for about half of the cases (Passmore et al. 2003).

As in adults, MDS without increase in blast count in children and adolescents can present with cytopenia and a hyperplastic bone marrow. However, in a retro- spective study on RC in childhood, about half of the cases had decreased marrow cell content (Kardos et al.

2003). In the ongoing prospective EWOG-MDS trial (Rogge and Niemeyer 2000), the percentage of hypocel- lular RC was 76% (Fig. 7.1). Compared with normo- or

Table 7.2. Results of cytogenetics of patients with primary MDS and with MDS secondary to chemo- or radiation therapy.

Interim analysis of Study EWOG-MDS 98

Karyotype Primary MDS (%) MDS secondary to

chemo- or radiation therapy (%) ( therapy (%) (nn=44) =44) All

((nn=199) =199)

RC ((nn=105) =105)

RAEB/RAEBt ((nn=94) =94)

Complex (³3 abnormalities) 6 3 9 36

Monosomy 7 24 17 32 23

Trisomy 8 4 3 5 0

Other abnormalities 9 5 14 23

Normal karyotype 57 72 40 18

hypercellular bone marrows, the percentage of patients with monosomy 7 was 11% in hypocellular marrows, while the percentage of children with normal karyo- types was 64% (Fig. 7.1). This observation, together with a low rate of leukemic transformation, raises the ques- tion whether some of the children with hypocellular RC and a normal karyotype have an unrecognized con- genital disorder with dysplasia and marrow failure rather than acquired MDS. In addition, the separation of RC from acquired severe aplastic anemia (SAA) can

be difficult. Differences in cytogenetic composition or response to immunosuppressive therapy among MDS and SAA study populations may depend at least in part on patient selection.

Karyotype is the most important factor for progres- sion of RC to advanced MDS and shortened survival (Kardos et al. 2003) (Fig. 7.2). The median time to pro- gression for children with RC and monosomy 7 is less than 2 years. In contrast to patients with monosomy 7, patients with trisomy 8 and other karyotypes may ex- perience a long stable course of their disease.

HSCT from a human leukocyte antigen (HLA)-com- patible related or unrelated donor early in the course of their disease is the treatment of choice for patients with RC and monosomy 7 (Anderson et al. 1996; Kardos et al.

2003). For children with normal karyotypes or chromo- somal abnormalities other than monosomy 7 and ab- sence of transfusion dependence or neutropenia, a watch and wait strategy can be appropriate. If cytopenia necessitates treatment, current therapeutic options in- clude HSCT with either myeloablative or reduced-inten- sity (Strahm et al. 2003) preparative therapies. Some pa- tients will respond to immunosuppressive therapy with cyclosporine and anti-lymphocyte/thymocyte globulin (Peters et al. 2003). Whether immunosuppression can result in sustained responses in a substantial number of children with RC is currently unknown. Therapy with hematopoietic growth factors, differentiating agents, or hypomethylating agents is generally felt not to be indi- cated in children and adolescents with RA because none of these approaches has been shown to prolong survival.

7.4.2 Primary MDS with Increased Blasts (RAEB and RAEBt)

There is consensus that the relationship between MDS and de novo AML is better defined by biological and clinical behavior than by myeloblast count. Conse- quently, myeloid disease with low blast count and cyto- genetic abnormalities typically associated with de novo AML is classified as AML. Because monosomy 7 is the only chromosomal abnormality strongly suggestive of MDS, children presenting with a low blast count and other chromosomal aberrations or normal karyotype have to be observed closely before a diagnosis of MDS can be established. Disease with rapid increase in mar- row blasts or organ infiltration should be considered de novo AML, which is by far the more common disorder.

84

Fig. 7.1. Cellularity and karyotype in 158 children with refractory cytopenia. Increased or normal cellularity for age was noted in 40 patients (24%) while 118 (76%) had decreased cellularity. Interim analysis of study EWOG-MDS 98 (November 2004)

Fig. 7.2. Cumulative incidence of progression to advanced MDS for patients with refractory cytopenia and either monosomy 7, trisomy 7or normal karyotype at the time of diagnosis. Patients who un- derwent stem cell transplantation were censored at the time of transplantation (adjusted from [12])

no information normal karyotype

To allow for the interface between MDS and de novo AML, RAEBt was retained in the pediatric classification until new data become available (Hasle et al. 2003).

The most appropriate therapy for childrenwith RAEB or RAEBt is unknown (Niemeyer et al. 2004; Webb et al.

2002; Woods et al. 2001). Although most investigators agree that HSCT can improve survival and is the treat- ment of choice, the importance of cytoreductive therapy prior to grafting remains controversial (Niemeyer et al.

2004; Webb et al. 2002). Data from the EWOG-MDS study indicate that intensive chemotherapy prior to HSCT will not improve survival (Niemeyer et al. 2004). In this study of advanced primary MDS, 88 patients with advanced MDS were given an unmanipulated graft after a prepara- tive regimen with busulfan (16 mg/kg), cyclophospha- mide (120 mg/kg), and melphalan (140 mg/m

). Thirty- eight patients were transplanted from HLA-identical/

1 antigen mismatched family donors, while 50 children received transplants from HLA-compatible/1 Ag mis- matched unrelated donors. The event-free survival at 5 years was 68% and 46% for HSCT from matched family and unrelated donors, respectively (Fig. 7.3). While the highest FAB type prior to SCT predicted relapse, with cumulative incidence rates increasing from RAEB to RAEBt and myelodysplasia-related AML, the use of in- tensive chemotherapy prior to SCT or blast percentage at SCT did not. Hopefully, well-controlled international clinical trials will resolve the issues on pre-HSCT remis- sion induction therapy, optimal preparative regimen, and stem cell source in the future.

7.5 Secondary MDS

7.5.1 MDS in Congenital Bone Marrow Failure Among the congenital bone marrow failure disorders, Fanconi anemia is the one most frequently evolving to hematopoietic neoplasia. MDS or AML develop in as many as 50% of patients with Fanconi anemia before the age of 40 years (Kutler et al. 2003). Because most pa- tients with Fanconi anemia have a dysplastic bone mar- row and the definition of clonality is problematic, it is difficult to diagnose MDS in Fanconi anemia in the ab- sence of an increased blast count. Because the natural history and therapy differ between MDS in Fanconi ane- mia and other patients, therapy results should be re- ported separately. For patients with severe congenital neutropenia (Kostmann syndrome), an incidence of MDS/AML of about 13% after 8 years of granulocyte- colony stimulating factor (G-CSF) treatment has been reported (Dale et al. 2003). In most Kostmann patients with MDS/AML, acquired mutations in the G-CSF re- ceptor are noted, and partial or complete loss of chro- mosome 7 is found in more than half (Kalra et al.

1995; Tidow et al. 1997). MDS may occur in as many as one third of patients with Shwachman-Diamond syn- drome (Smith 2002), but has less frequently been de- scribed in patients with Diamond-Blackfan anemia (Hansen and Martin 1982; Janov et al. 1996; Martin et al. 1981). It is noteworthy that not all bone marrow fail- ure syndromes predispose to the development of MDS, e.g., patients with dyskeratosis congenita develop bone marrow failure (aplastic anemia) in 95% of the cases but MDS is rare (Dokal 2000).

7.5.2 MDS After Acquired Aplastic Anemia MDS develops in 10±15% of children with aplastic ane- mia not treated with HSCT (Ascensao et al. 1976; Kojima et al. 2002; Locasciulli et al. 2001; Rosenfeld et al. 1985;

Tichelli et al. 1988). Most cases of MDS in children are diagnosed within the first 3 years from presentation with aplastic anemia. The fast progression to MDS raises the question whether at least some of the patients had MDS from the beginning. One might also speculate that there is a biological overlap between aplastic ane- mia and hypoplastic RC.

Fig. 7.3. Event-free survival of 88 patients with primary advanced MDS transplanted after a preparative regimen with busulfan 16 mg/

kg, cyclophosphamid 120 mg/kg and melphalan 140 mg/m

from an HLA-identical/1 Ag mismatched family donor (MFD) (N=38) or an HLA-compatible/1 Ag mismatched unrelated donors (UD) (N=50) (Niemeyer et al. 2004)

ProbabilityofEvent-freeSurvival

7.5.3 Familial MDS

Familial occurrence of MDS, especially with ±7/7q-, has been reported in a number of cases (Anasetti et al. 1987;

Hasle and Olsen 1997; Shannon et al. 1989; Singer et al.

1983; Storb et al. 1983; Thomas et al. 1984). Some fami- lies show discordance for ±7; therefore, it is uncertain whether ±7 per se increases the risk for familiar cases.

The inherited predisposing locus in familial MDS or AML with ±7/7q- may not be located on chromosome 7 (Gao et al. 2000). Familial MDS does also occur with- out ±7/7q- (Press et al. 1986).

7.5.4 Therapy-related MDS

New intensive treatment protocols for various disorders may lead to an increased risk of therapy-related diseases (Barnard et al. 2002). Children with MDS secondary to chemo- or radiation therapy generally have a poor sur- vival (Sasaki et al. 2001). Even if remission can be achieved with AML-type therapy, only very few patients remain disease-free, and only HSCT offer cure in about a third of the patients (Badger and Bernstein 1983; L'Es- perance et al. 1975).

Summary

The proposal of the pediatric modification of the WHO classification of MDS reflects our current state of knowl- edge. With additional information on the underlying biological processes concepts and therapies will change.

In children with refractory cytopenia a watch and wait strategy or immunosuppressive therapy can be appro- priate in the absence of monosomy 7. In all other cases, HSCT is the treatment of choice. With the possibility to cure at least half of the children with MDS, there is very little room for palliative therapy approaches.

References

Anasetti C, Martin PJ, Morishita Y, Ledbetter JA, Hansen JA (1987) En- hancement of cytolytic activity by bridging the CD2 sheep eryth- rocyte binding protein and the CD16 Fc-receptor. In: McMichael AJ (ed) Leukocyte typing III. Oxford University Press, Oxford, pp 131±133

Anderson JE, Appelbaum FR, Schoch G, Gooley T, Anasetti C, Bensinger WI, Bryant E, Buckner CD, Chauncey TR, Clift RA, Doney K, Flowers

M, Hansen JA, Martin PJ, Matthews DC, Sanders JE, Shulman H, Sullivan KM, Witherspoon RP, Storb R (1996) Allogeneic marrow transplantation for refractory anemia: a comparison of two pre- parative regimens and analysis of prognostic factors. Blood 87:51±58

Ascensao J, Pahwa R, Kagan W, Hansen J, Moore M, Good R (1976) Aplastic anaemia: evidence for an immunological mechanism.

Lancet 1:669±671

Bader-Meunier B, Mielot F, Tchernia G, Buisine J, Delsol G, Duchayne E, Lemerle S, Leverger G, de Lumley L, Manel AM (1996) Myelodys- plastic syndromes in childhood: report of 49 patients from a French multicentre study. Br J Haematol 92:344±350

Badger CC, Bernstein ID (1983) Prospects for antibody therapy of leu- kemia: experimental studies in murine leukemia. In: Langman RE, Trowbridge IS, Dulbecco R (eds) Monoclonal antibodies and can- cer, proceedings of the 4th Armand Hammer Cancer Symposium.

Academic Press, pp 63±72

Barnard DR, Lange B, Alonzo TA, Buckley J, Kobrinsky JN, Gold S, Neu- dorf S, Sanders J, Burden L, Woods WG (2002) Acute myeloid leu- kemia and myelodysplastic syndrome in children treated for can- cer: comparison with primary presentation. Blood 100:427±434 Brandwein JM, Horsman DE, Eaves AC, Eaves CJ, Massing BG, Wads-

worth LD, Rogers PC, Kalousek DK (1990) Childhood myelodyspla- sia: suggested classification as myelodysplastic syndromes based on laboratory and clinical findings. Am J Ped Hematol Onc 12:63±

70

Chan GCF, Wang WC, Raimondi SC, Behm FG, Krance RA, Chen G, Frei- berg A, Ingram L, Butler D, Head DR (1997) Myelodysplastic syn- drome in children: differentiation from acute myeloid leukemia with a low blast count (Review). Leukemia 11:206±211 Dale DC, Cottle TE, Fier CJ, Bolyard AA, Bonilla MA, Boxer LA, Cham B,

Freedman MH, Kannourakis G, Kinsey SE, Davis R, Scarlata D, Schwinzer B, Zeidler C, Welte K (2003) Severe chronic neutropenia:

treatment and follow-up of patients in the Severe Chronic Neutro- penia International Registry (Review). Am J Hematol 72:82±93 Dokal I (2000) Dyskeratosis congenita in all its forms (Review). Br J

Haematol 110:768±779

Gao Q, Horwitz M, Roulston D, Hagos F, Zhao N, Freireich EJ, Golomb HM, Olopade OI (2000) Susceptibility gene for familial acute mye- loid leukemia associated with loss of 5q and/or 7q is not localized on the commonly deleted portion of 5q. Genes Chromosomes Cancer 28:164±172

Groupe Francais de Cytogenetique Hematologique (1997) Forty-four cases of childhood myelodysplasia with cytogenetics, documen- ted by the Groupe Francais de Cytogenetique Hematologique.

Leukemia 11:1478±1485

Hansen JA, Martin PJ (1982) Human T cell differentiation antigens. In:

Mitchell MS, Oettgen HF (eds) Hybridomas in cancer diagnosis and treatment. Progress in cancer research and therapy. Raven Press, New York, pp 75±88

Hasle H, Olsen JH (1997) Cancer in relatives of children with myelodys- plastic syndrome, acute and chronic myeloid leukaemia. Br J Haematol 97:127±131

Hasle H, Kerndrup G, Jacobsen BB (1995) Childhood myelodysplastic syndrome in Denmark: incidence and predisposing conditions.

Leukemia 9:1569±1572

Hasle H, Arico M, Basso G, Biondi A, Cantu Rajnoldi A, Creutzig U, Fenu

S, Fonatsch C, Haas OA, Harbott J, Kardos G, Kerndrup G, Mann G,

86

Niemeyer CM, Ptoszkova H, Ritter J, Slater R, Stary J, Stollmann- Gibbels B, Testi AM, van Wering ER, Zimmermann M (1999a) Mye- lodysplastic syndrome, juvenile myelomonocytic leukemia, and acute myeloid leukemia associated with complete or partial monosomy 7. Leukemia 13:376±385

Hasle H, Wadsworth LD, Massing BG, McBride M, Schultz KR (1999b) A population-based study of childhood myelodysplastic syndrome in British Columbia, Canada. Br J Haematol 106:1027±1032 Hasle H, Niemeyer CM, Chessells JM, Baumann I, Bennett JM, Kerndrup

G, Head DR (2003) A pediatric approach to the WHO classification of myelodysplastic and myeloproliferative diseases (Review). Leu- kemia 17:277±282

Jaffe ES, Harris NL, Stein H, Vardiman JW (ed) (2001) World Health Or- ganization classification of tumours. Pathology & genetics: tu- mours of hematopoietic and lymphoid tissues. IARCPress, Wash- ington, DC

Janov AJ, Leong T, Nathan DG, Guinan EC (1996) Diamond-Blackfan anemia. Natural history and sequelae of treatment. Medicine 75:77±78

Kalra R, Dale D, Freedman M, Bonilla MA, Weinblatt M, Ganser A, Bow- man P, Abish S, Priest J, Oseas RS (1995) Monosomy 7and activat- ing RAS mutations accompany malignant transformation in pa- tients with congenital neutropenia. Blood 86:4579±4586 Kardos G, Baumann I, Passmore SJ, Locatelli F, Hasle H, Schultz KR, Stary

J, Schmitt-Graeff A, Fischer A, Harbott J, Chessells JM, Hann I, Fenu S, Rajnoldi AC, Kerndrup G, Van Wering E, Rogge T, Nollke P, Nie- meyer CM (2003) Refractory anemia in childhood: a retrospective analysis of 67patients with particular reference to monosomy 7.

Blood 102:1997±2003

Ketterling RP, Wyatt WA, VanWier SA, Law M, Hodnefield JM, Hanson CA, Dewald GW (2002) Primary myelodysplastic syndrome with normal cytogenetics: utility of 'FISH panel testing' and M-FISH.

Leuk Res 26:235±240

Kojima S, Ohara A, Tsuchida M, Kudoh T, Hanada R, Okimoto Y, Kaneko T, Takano T, Ikuta K, Tsukimoto I (2002) Risk factors for evolution of acquired aplastic anemia into myelodysplastic syndrome and acute myeloid leukemia after immunosuppressive therapy in chil- dren. Blood 100:786±790

Kutler DI, Singh B, Satagopan J, Batish SD, Berwick M, Giampietro PF, Hanenberg H, Auerbach AD (2003) A 20-year perspective on the International Fanconi Anemia Registry (IFAR). Blood 101:1249±

1256

L'Esperance P, Hansen JA, Jersild C, O'Reilly R, Good RA, Thomsen M, Nielsen LS, Svejgaard A, Dupont B (1975) Bone-marrow donor se- lection among unrelated four-locus identical individuals. Trans- plant Proc [Suppl 1]:823±831

Locasciulli A, Arcese W, Locatelli F, Di Bona E, Bacigalupo A (2001) Treatment of aplastic anaemia with granulocyte-colony stimulat- ing factor and risk of malignancy. Lancet 357:43±44

Luna-Fineman S, Shannon KM, Atwater SK, Davis J, Masterson M, Or- tega J, Sanders J, Steinherz P, Weinberg V, Lange BJ (1999) Mye- lodysplastic and myeloproliferative disorders of childhood: a study of 167patients. Blood 93:459±466

Mandel K, Dror Y, Poon A, Freedman MH (2002) A practical, compre- hensive classification for pediatric myelodysplastic syndromes:

the CCC system [republished from J Pediatr Hematol Oncol 2002 24:343±352]. J Pediatr Hematol Oncol 24:596±605

Martin PJ, Hansen JA, Siadak AW, Nowinski RC (1981) Monoclonal anti- bodies recognizing normal human T lymphocytes and malignant human B lymphocytes: a comparative study. J Immunol 127:1920±

1923

Niemeyer CM, Zecca M, Korthoff E, Duffner U, Zintl F, Ebell W, Stary J, Dilloo D, Peters C, Schmugge M, Sedlacek P, Messina C, van Heuvel M, Bergstraesser E, Trebo M, Noelke P, Locatelli F (2004) Allogeneic stem cell transplantation for children with advanced primary MDS:

results from the EWOG-MDS Study Group employing a pre-trans- plant preparative regimen with busulfan, cyclophosphamide and melphalan (Abstract). Blood 104:632 a

Passmore SJ, Hann IM, Stiller CA, Ramani P, Swansbury GJ, Gibbons B, Reeves BR, Chessells JM (1995) Pediatric myelodysplasia: a study of 68 children and a new prognostic scoring system. Blood 85:1742±1750

Passmore SJ, Chessells JM, Kempski H, Hann IM, Brownbill PA, Stiller CA (2003) Paediatric myelodysplastic syndromes and juvenile myelo- monocytic leukaemia in the UK: a population-based study of in- cidence and survival. Br J Haematol 121:758±767

Peters AMJ, Baumann I, Strahm B, Gerecke A, Bergstraesser E, Burdach S, Dilloo D, Fenu S, Holter W, Klingebiel T, Koscielniak E, Welte K, Fischer A, Fuehrer M, Niemeyer CM (2003) Immunosuppressive therapy for children with refractory anemia (Abstract). Bone Mar- row Transplant 31[Suppl 1]: S183, #P670

Press OW, Vitetta ES, Martin PJ (1986) A simplified microassay for in- hibition of protein synthesis in reticulocyte lysates by immunotox- ins. Immunol Lett 14:37±41

Rogge T, Niemeyer CM (2000) Myelodysplastic syndromes in child- hood. Onkologie 23:18±24

Rosenfeld M, Bowen-Pope DF, Singer JW, Ross R (1985) Responsiveness of the in vitro hematopoietic microenvironment to platelet-de- rived growth factor. Leuk Res 9:427±434

Sasaki H, Manabe A, Kojima S, Tsuchida M, Hayashi Y, Ikuta K, Okamura I, Koike K, Ohara A, Ishii E, Komada Y, Hibi S, Nakahata T, MDS Com- mittee of the Japanese Society of Pediatric Hematology J (2001) Myelodysplastic syndrome in childhood: a retrospective study of 189 patients in Japan. Leukemia 15:1713±1720

Shannon KM, Turhan AG, Chang SS, Bowcock AM, Rogers PC, Carroll WL, Cowan MJ, Glader BE, Eaves CJ, Eaves AC (1989) Familial bone marrow monosomy 7. Evidence that the predisposing locus is not on the long arm of chromosome 7. J Clin Invest 84:984±989 Singer JW, Keating A, Ramberg R, McGuffin R, Sanders JE, Sale G, Fial-

kow PJ, Thomas ED (1983) Long-term stable hematopoietic chim- erism following marrow transplantation for acute lymphoblastic leukemia: a case report with in vitro marrow culture studies. Blood 62:869±872

Smith OP (2002) Shwachman-Diamond syndrome (Review). Semin Hematol 39:95±102

Storb R, Deeg HJ, Thomas ED, Buckner CD, Clift RA, Flournoy N, Ken- nedy MS, Doney K, Appelbaum FR, Sanders JE, Stewart P, Shulman H, Sullivan KM, Witherspoon RP (1983) Preliminary results of pro- spective randomized trials comparing methotrexate and cyclo- sporine for prophylaxis of graft-vs.-host-disease after HLA-identi- cal marrow transplantation. Transplant Proc 15:2620±2623 Strahm B, Greil J, Kremens B, Peters C, Stary J, Vormoor J, Zintl F, Rogge

T, Locatelli F, Niemeyer CM (2003) A new conditioning regimen for

patients with refractory anemia and congenital disorders (Ab-

stract). Bone Marrow Transplant 31[Suppl 1]: S26, #198

Thomas ED, Clift RA, Storb R (1984) Indications for marrow transplan- tation. Annu Rev Med 35:1±9

Tichelli A, Gratwohl A, Wursch A, Nissen C, Speck B (1988) Late haema- tological complications in severe aplastic anaemia. Br J Haematol 69:413±418

Tidow N, Pilz C, Teichmann B, Muller-Brechlin A, Germeshausen M, Kas- per B, Rauprich P, Sykora KW, Welte K (1997) Clinical relevance of point mutations in the cytoplasmic domain of the granulocyte colony-stimulating factor receptor gene in patients with severe congenital neutropenia. Blood 89:2369±2375

Webb DK, Passmore SJ, Hann IM, Harrison G, Wheatley K, Chessells JM (2002) Results of treatment of children with refractory anaemia

with excess blasts (RAEB) and RAEB in transformation (RAEBt) in Great Britain 1990-1999 (Review). Br J Haematol 117:33±39 Woods WG, Neudorf S, Gold S, Sanders J, Buckley JD, Barnard DR, Du-

senbery K, DeSwarte J, Arthur DC, Lange BJ, Kobrinsky NL (2001) A comparison of allogeneic bone marrow transplantation, autolo- gous bone marrow transplantation, and aggressive chemother- apy in children with acute myeloid leukemia in remission: a report from the Children's Cancer Group. Blood 97:56±62

Woods WG, Barnard DR, Alonzo TA, Buckley JD, Kobrinsky N, Arthur DC, Sanders J, Neudorf S, Gold S, Lange BJ (2002) Prospective study of 90 children requiring treatment for juvenile myelomonocytic leu- kemia or myelodysplastic syndrome: a report from the Children's Cancer Group. J Clin Oncol 20:434±440

88