What Is the Clinical Utility of Repeat SNP Array Testing in the Follow-up of Myeloid Neoplasms?: A Retrospective Analysis of 44 Patients With Serial SNP Arrays.

Objectives: Single-nucleotide polymorphism (SNP) arrays have been shown to identify cytogenetic abnormalities in myeloid neoplasms that may be missed by metaphase cytogenetics alone at initial diagnosis. This study examines the utility of serial SNP arrays in follow-up testing of myeloid neoplasms.

Methods: We retrospectively reviewed results of SNP array testing in 44 patients with myeloid neoplasms and more than one SNP array study (n = 133 SNP arrays total; median, three per patient; range, two to eight per patient).

Results: Baseline abnormalities were identified by SNP array in 35 (79%) of 44 (79%) compared with 18 (50%) of 36 by metaphase karyotype. In follow-up studies, clonal evolution was found by both SNP array and karyotyping in seven (15.9%), by metaphase karyotyping alone in six (13.6%), and SNP arrays alone in two (4.5%). Overall survival was not significantly different between patients with or without clonal evolution detected by SNP array.

Conclusions: This study, the first systematic examination of serial SNP arrays in myeloid neoplasms, confirms the clinical utility of SNP arrays at initial diagnosis but shows that clonal evolution of the karyotype can be detected by metaphase cytogenetics alone in most patients. Follow-up SNP array testing is not required in routine clinical use in most cases.