What is the primary mechanism involved in imprinting disorders?

Imprinting disorders primarily arise from abnormal genetic expression patterns that occur when certain genes are expressed in a parent-of-origin-specific manner. This means that only the allele (gene variant) inherited from either the mother or the father is expressed, while the other allele is silenced. DNA methylation is a key regulatory mechanism that contributes to this silencing effect.

In imprinting, specific genes are marked by methylation during gamete formation, and these methylation patterns are maintained after fertilization. If there are errors in this process—such as improper methylation, which can occur through mutations or environmental factors—then an imprinting disorder can develop. These disorders include conditions like Prader-Willi syndrome and Angelman syndrome, which result from the lack of expression of imprinted genes from one parent due to altered methylation patterns.

Given the mechanism of imprinting disorders relies heavily on the epigenetic modifications of DNA, particularly DNA methylation, this is the correct answer.