Acquired CN-LOH of chromosome 1p in patients with MPN and high MPL-mutant allele burden. (Upper panel, A) Analysis of the two telomeric SNPs rs760567 and rs2073025 mapping on chromosome 1p36.32 and 1p34.3, respectively; the two centromeric SNPs rs2297634 and rs1801574 located at 1p22.1; and the intronic SNP rs839995 in 8 MPN patients with an MPL mutation burden >75%. Black circles indicate chromosome 1pLOH in granulocytes as detected by the corresponding polymorphic marker, white circles indicate the absence of 1pLOH, and gray circles indicate noninformative loci. Vertical lines represent individual patients. This analysis showed 1pLOH, always involving the location of MPL in 1p34, in 7 of the 8 patients studied; the remaining patient (09_191, second patient from left) was not informative. With respect to chromosome 1p34, telomeric sequences were involved in 1pLOH in all informative patients, although centromeric sequences were involved in only a subset of patients. (Lower panel, B) Evaluation of number of copies of MPL in patients with 1pLOH. Data are shown in a box plot depicting the lower and upper adjacent values (lowest and highest horizontal line, respectively), lower and upper quartile with median value (box) and outliers (dots). No significant difference in MPL copy number was found between granulocytes (gran) and T lymphocytes from patients with 1pLOH (P = .54), as well as between patients and healthy participants (P = .12), although significant differences were found with respect to the SRY gene (P < .001).