[Study on Differential DNA Methylation Profiles of Patients with High-Altitude Polycythemia]

To investigate the whole-genome differential methylation profile of patients with high-altitude polycythemia (HAPC).

In this study, a total of 20 adult male patients with HAPC were included, including 10 Tibetan and 10 Han patients. The control group consisted of 20 healthy adult males, including 10 Tibetan and 10 Han patients. Peripheral blood was collected from each group for DNA extraction and quality inspection, and DNA libraries were constructed. The differential methylation regions (DMRs) between groups were detected using reduced representation bisulfite sequencing, with enriched regions compared to those of the control group. The differential enrichment regions were selected, and the intersection of the enriched regions was associated with genes. The methylation enrichment regions that differed significantly between groups were filtered based on the number of enriched samples in the enriched regions between the groups. GO, KEGG functional, and pathway analysis were performed on the differentially associated gene sets to reveal significant differences between the patients and control groups at the functional and pathway levels.

In comparison with the control group, 17 152 sites with more than 25% difference and 15 558 sites with less than -25% difference were identified in Tibetan patients. The top 5 genes with the largest methylation differences between the two groups were MCCC2, RP3-399L15.3, ZNF621, RP11-394A14.2 and SLC39A10. The top significantly different pathways annotated in the differentially expressed genes pathway was serotonergic synapse. In comparison with the control group, 2 687 CpG sites with a greater than 25% difference and 2 602 CpG sites with a less than -25% difference were identified in Han patients. The top 5 genes with the largest methylation differences between the two groups were NAA25, CORO2B, PDC, ZNF853, and MLLT10. The top significantly different pathways annotated in the differentially expressed genes pathway were glutamatergic synapse, retrograde endocannabinoid signaling, Rap1 signaling pathway and cholinergic synapse. In comparison with the control group, 3 895 CpG sites with a greater than 25% difference and 3 969 CpG sites with a less than -25% difference were identified in HAPC patients. The maximum methylation difference between the two groups could reach 78.1%, while the minimum was -42.6%. The top 5 genes with the largest methylation differences between the two groups were MCCC2, ARSJ, CTNNA3, SLC39A10, and SWAP70. The top significantly different pathways annotated in the differentially expressed genes pathway was signaling pathways regulating pluripotency of stem cells.

The occurrence of HAPC may be related to abnormal changes in DNA methylation, and methylation sites may be helpful for the early diagnosis of HAPC.