Relationship between DNA Methylation within the YJEFN3 Gene and Cognitive Deficit in Schizophrenia Spectrum Disorders

The study investigated methylation of each cytosine within a fragment of the YJEFN3 gene located at one of the index loci of schizophrenia risk with the aim to determine whether methylation of this fragment is associated with the level of cognitive deficit in patients and to what extent it depends on the risk haplotype. Peripheral blood samples from 70 schizophrenia spectrum patients and 72 healthy subjects who underwent cognitive testing were examined using single-molecule real-time bisulfite sequencing. A negative correlation was found between methylation of the CpG site at chr19:19532203, hg38 (Illumina ID: cg08623644) and the cognitive index in patients. Methylation at cg08623644 was associated with the risk haplotype in the pooled sample and in healthy subjects. The patients showed a weakening of this association. The findings suggest that methylation at cg08623644 may be a peripheral marker of molecular processes associated with the severity of the disease, which deserves further investigation.