Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

[Q]: Context: Rapa Nui (Easter Island), located in the easternmost corner of the Polynesian Triangle, is one of the most isolated locations on the planet inhabited by humans. Archaeological and genetic evidence suggests that the island was first colonized by Polynesians around AD 1200, during their eastward expansion. Although it remains contentious whether Polynesians reached South America, suggestive evidence has been brought forward supporting the possibility of Native American contact prior to the European "discovery" of the island in AD 1722.', 'We generated genome-wide data for 27 Rapanui. We found a mostly Polynesian ancestry among Rapanui and detected genome-wide patterns consistent with Native American and European admixture. By considering the distribution of local ancestry tracts of eight unrelated Rapanui, we found statistical support for Native American admixture dating to AD 1280-1495 and European admixture dating to AD 1850-1895.
Answer: These genetic results can be explained by one or more pre-European trans-Pacific contacts.
[A]: Do genome-wide ancestry patterns in Rapanui suggest pre-European admixture with Native Americans?


[Q]: Context: DNA methylation at CpG dinucleotides is modified in tumorigenesis with potential impact on transcriptional activity.', 'We used the Illumina 450 K platform to evaluate DNA methylation patterns of 50 metastatic melanoma tumors, with matched gene expression data.', 'We identified three different methylation groups and validated the groups in independent data from The Cancer Genome Atlas. One group displayed hypermethylation of a developmental promoter set, genome-wide demethylation, increased proliferation and activity of the SWI/SNF complex. A second group had a methylation pattern resembling stromal and leukocyte cells, over-expressed an immune signature and had improved survival rates in metastatic tumors (p < 0.05). A third group had intermediate methylation levels and expressed both proliferative and immune signatures. The methylation groups corresponded to some degree with previously identified gene expression phenotypes.
Answer: Melanoma consists of divergent methylation groups that are distinguished by promoter methylation, proliferation and content of immunological cells.
[A]: Are dNA methylation subgroups in melanoma associated with proliferative and immunological processes?


[Q]: Context: The atherosclerotic process progresses more dynamically in hemodialysis (HD) patients than in the general population. In HD patients, lower magnesium levels were reported to be associated with increased atherosclerosis of the common carotid artery. We tested the hypotheses that magnesium supplementation helps to improve carotid intima media thickness (IMT) in HD patients.', 'A total of 47 patients on HD were included in the study. Patients were randomly divided into two groups: group A (Mg group), in which patients were given magnesium citrate orally at a dosage of 610 mg every other day for 2 months and group B (control group), in which patients received only calcium acetate therapy as a phosphate binder. At baseline and 2 months later, all patients underwent a carotid artery ultrasound scan to measure carotid IMT.', 'At the end of 2 months, mean serum calcium, phosphorus, and calcium x phosphorus product were not changed in both groups. As expected, mean serum Mg level significantly increased in the Mg group at the end of 2 months. In addition, serum parathyroid hormone (PTH) level significantly decreased in the Mg group at the end of 2 months (P = 0.003). Baseline carotid IMT was similar between the groups. Bilateral carotid IMT was significantly improved in patients treated with magnesium citrate compared to initial values (P = 0.001 for left, P = 0.002 for right).
Answer: Based on the present data, magnesium may play an important protective role in the progression of atherosclerosis in patients on dialysis. Further studies are needed to assess more accurately the role of magnesium in atherosclerotic regression in dialysis patients.
[A]:
Does magnesium supplementation help to improve carotid intima media thickness in patients on hemodialysis?