Volumen: 12 # Number : 3
Publication Date : Septiembre - Diciembre Year: 2008
Authors: Fernando Luiz Lopes
Abstract: The myelodysplastic syndromes (MDS) are a
group of clonal stem cell disorders characterized by
cytopenia, ineffective hematopoiesis and hypercellular
bone marrow.
Overall, MDS is the most common hematological
malignancy in the elderly. In children the incidence
is lower but effective treatment of both adults and
children in the advanced stages of the disease is problematic.
Some patients show a prolonged and stable
clinical course without treatment, but most cases will
eventually progress. Hematopoietic stem cell transplantation
(HSCT) is the treatment of choice, but the
outcome following HSCT is jeopardized if disease
progression has occurred.
The clinical course of MDS can be divided into several
distinct phases related to the percentage of
leukemic blasts in bone marrow. In the early, indolent
stage, affected individuals manifest only cytopenia.
Information on prognostic factors predicting progression
or death is important in the planning of
therapy. There have been few systematic attempts to
define a prognostic score in pediatric MDS. A prognostic
scoring system proposed by the British group1
assigned one point each to fetal hemoglobin (HbF),
platelet count, and two or more cytogenetic abnormalities
(FPC score). A significantly superior survival was found in children with an FPC score of zero. The
score has not been applied to other large series of
children with MDS mainly because HbF is not routinely
evaluated in MDS patients The International
Prognostic Scoring System (IPSS) was developed for
adult MDS and includes weighted data on BM blast
percentage, cytopenia, and cytogenetics, dividing
patients into four prognostic groups. The IPSS has
shown strong prognostic value in adults with MDS
but not the same application to children.
The development of an effective treatment for
MDS will require the characterization of the molecular
mechanism that underlies stage progression.
Many chromosomal abnormalities (e.g. 5q- and
monosomy 7) have been detected in adult MDS patients
and several studies of gene profile by cDNA
microarray have been conducted on hematopoietic
cells from adult MDS patients and the specific
changes identified are likely to be biologically important
markers for the various stages of this disorder.
Cytogenetic alterations are well documented in
pediatric MDS and chromosome 7 is frequently altered
(monosomy 7 or deletion 7q). Although some
of these alterations are associated to a poor prognosis,
the molecular alterations involved in the initiation
and evolution of the disease remain unknown
Key words:
Pages : 77
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