Searching Polymorphic Markers Associated with the Genetic Predisposition To Develop Therapy-Related Myelodysplastic Syndromes and Acute Myelogenous Leukemia T-(MDS/AML) after Myeloablative Chemotherapy.

INTRODUCTION: Therapy-related MDS/AML constitutes the most frequent secondary neoplasia and his incidence is increasing in the last years. This incidence is especially high when myeloablative chemotherapy is used before autologous stem cell transplantation (ASCT). Since for similar treatments only a percentage of the patients ends up by developing a secondary leukemia, it has been proposed the existence of some type of genetic predisposition associated to this syndrome.

OBJETIVE: To search single nucleotide polymorphisms (SNPs) associated with the genetic predisposition to develop a t-MDS/AML by means of SNP genome screening using high density microarrays.

MATERIAL AND METHODS: Two groups of individuals were genotyped: Group A, composed by 16 patients with t-MDS/AML post-ASCT (10 NHL, 4 HD, 2 multiple myeloma) and Group B (control), formed by 16 patients submitted to ASCT and that after a period of more than 10 years have not developed t-MDS/AML(14 NHL, 2 HD). For each individual more than 10.000 SNPs were genotyped by means of the use of microarrays of high density (Mapping 10K, Affymetrix®). Those SNPs are distributed along the whole genome and have a high average heterocigosity (0,37). The alele frequencies for each SNP between two groups were compared.

RESULTS: We found a group of 4 SNPs located in the q23.3 band of the chromosome 5 in which the differences of alele frequency between the groups A and B were superior to 50 %. These SNPs are located in a region that comprises the only gene, CSS3 (chondroitin sulphate synthetase 3), being the difference of alele frequency of 57 % in the intronic SNP of this gene.

CONCLUSIONS: The results suggest that the CSS3 gene is a candidate for being studied by its possible relation with the genetic predisposition to develop LMAt/SMDt, although its putative functional implication with the disease must still be elucidated. There is known that a counterpart of CSS3, CSS1, plays a key role in the proliferation and apoptosis of myeloma cells. Thus, it is possible that CSS3 could be somehow related with the hematopoyesis pathways and implied in the development of t-MDS/AML. Financed by FIS G03/008.