The Klinefelter Syndrome (XXY) Reference Material can be used to develop a new test, validate an assay, monitor routine performance, troubleshoot problems across the entire workflow and ensure overall proficiency with the same sustainable product. Matched (or related) maternal-fetal XXY sample compatible with a broad range of NIPT assay methods. Proprietary method maintains native cfDNA size profile of ~170 bp size distribution and natural maternal-fetal size difference offered in a plasma format capable of assessing the entire workflow from extraction through analysis (identical to clinical samples). Fetal fraction levels confirmed to be moderate-high positive to help establish initial baseline (can be customized to lower levels).