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Structural genomic variation analysis in patients with bone marrow failure using Illumina Infinium SNP Arrays [Illumina Quad610 Beadchip]

ABSTRACT: To better understand the natural history of bone marrow failure syndromes, we analyzed 124 single nucleotide polymorphism arrays (SNP-A) from a comprehensively characterized cohort of 91 patients who had SNP-A for clinical evaluation of BMFS. 67 samples from 51 patients were genotyped with the Quad610, and 57 samples from 54 patients were genotyped with the Omni1-Quad. This submission includes 67 samples from 51 patients that were genotyped with Illumina Quad610 Beadchip.

ORGANISM(S): Homo sapiens

PROVIDER: GSE48483 | GEO | 2014/01/01

SECONDARY ACCESSION(S): PRJNA210312

REPOSITORIES: GEO

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Project description:BACKGROUND: Measurement of genome-wide DNA methylation (DNAm) has become an important avenue for investigating potential physiologically-relevant epigenetic changes. Illumina Infinium (Illumina, San Diego, CA, USA) is a commercially available microarray suite used to measure DNAm at many sites throughout the genome. However, it has been suggested that a subset of array probes may give misleading results due to issues related to probe design. To facilitate biologically significant data interpretation, we set out to enhance probe annotation of the newest Infinium array, the HumanMethylation450 BeadChip (450 k), with >485,000 probes covering 99% of Reference Sequence (RefSeq) genes (National Center for Biotechnology Information (NCBI), Bethesda, MD, USA). Annotation that was added or expanded on includes: 1) documented SNPs in the probe target, 2) probe binding specificity, 3) CpG classification of target sites and 4) gene feature classification of target sites. RESULTS: Probes with documented SNPs at the target CpG (4.3% of probes) were associated with increased within-tissue variation in DNAm. An example of a probe with a SNP at the target CpG demonstrated how sample genotype can confound the measurement of DNAm. Additionally, 8.6% of probes mapped to multiple locations in silico. Measurements from these non-specific probes likely represent a combination of DNAm from multiple genomic sites. The expanded biological annotation demonstrated that based on DNAm, grouping probes by an alternative high-density and intermediate-density CpG island classification provided a distinctive pattern of DNAm. Finally, variable enrichment for differentially methylated probes was noted across CpG classes and gene feature groups, dependant on the tissues that were compared. CONCLUSION: DNAm arrays offer a high-throughput approach for which careful consideration of probe content should be utilized to better understand the biological processes affected. Probes containing SNPs and non-specific probes may affect the assessment of DNAm using the 450 k array. Additionally, probe classification by CpG enrichment classes and to a lesser extent gene feature groups resulted in distinct patterns of DNAm. Thus, we recommend that compromised probes be removed from analyses and that the genomic context of DNAm is considered in studies deciphering the biological meaning of Illumina 450 k array data.

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Structural genomic variation analysis in patients with bone marrow failure using Illumina Infinium SNP Arrays [Illumina Quad610 Beadchip]

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