Genome Wide Analysis of 41 Mycosis Fungoides Tumor Stage Using Array Comparative Genomic Hybridization Technology.

Introduction: Primary cutaneous T cell lymphomas (CTCL) represent 70% of all cutaneous lymphomas. The most frequent is mycosis fungoides/Sézary syndrome (MF/ SS). In this entity, few high resolution cytogenetic studies have been performed. Our aim was to analyze chromosomal abnormalities in MF tumoral stage by array comparative genomic hybridization (ArrayCGH) and to describe potential candidate genes related to this disease.

Patients and methods: Forty-one patients (22 males/19 females) with MF tumor stage were included from centres collaborating in the EORTC Cutaneous Lymphoma Group. DNA was extracted from frozen tissues containing more than 70% of tumor cells. ArrayCGH tecnhology was performed to detect genomic imbalances (gains/losses) using the Humane Genome CGH Microarray Kit 44B (Agilent Techologies). This array consists on 44.000 oligo probes of 60 bp covering all the human genome with a mean resolution of 50–100 Kb. CGH-Analytics 3.2.25 and InSilicoArray CGH (http://isacgh.bioinfo.cipf.es) was used for array analysis and to define SORIs (Smallest Overlapping Region of Imbalance).

Results: Genomic abnormalities were observed in thirty-two cases (76%). Losses (62.36%) were more frequently detected than gains (37.64%). The mean chromosomal imbalances per case were 3.5 gains (0–14) and 5.6 losses (0–30). The minimal common regions altered were gains of 7q33.3 (55%), 17q21.1q21.3 (42.5%) and 8q24.21. Regarding to the losses, 9p21.3 (42,5%), 17p13.1 (42,5%) and 10p11.22 (17,5%) were the most frequent detected. SORIs and potential candidates genes from the most frequently altered regions are summarized in the following table.

Conclusions: Our results have shown high recurrent chromosomal abnormalities. Moreover, arrayCGH technology has allowed us to define in detail new common regions and to describe potential candidate genes in MF tumor stage as STAT5A/STA5B (17q21.2), BRAF (7q33) and TCF8 (10p11.22). Our findings are similar to those recently published by Vermeer et al in Sézary Syndrome, which lead to confirm the relationship between these two entities. Deletion of 9p21.3 (CDKN2A, CDKN2B, MTAP genes) and 17p13.1 (TP53) are concordance to previous studies.