For 10 points, name this dosage compensation effect in mammals that results in the formation of a Barr body.
Proximity to CTCF binding sites is thought to correlate with escape from this effect, as in the case of Jarid1C. In mammals, all variants of the modified histone macro-H2A participate in this process. Models to explain this process frequently invoke blocking factors, competence factors, and/or counting factors. In Drosophila, which lacks this phenomenon, the male-specific lethal gene product upregulates transcription of a certain subset of genes, while in mammals, this process requires the expression of a cis-acting namesake "specific transcript" which coats chromatin. This process begins at the two- or four-cell stage in mammals, and the randomness of this phenomenon is responsible for coat color in calico cats. For 10 points, name this dosage compensation effect in mammals that results in the formation of a Barr body.
Proximity to CTCF binding sites is thought to correlate with escape from this effect, as in the case of Jarid1C.
{X chromosome inactivation} [accept word forms; accept {lyonization;} accept {Barr body formation} or {condensation} or equivalents before Barr bodies are mentioned; accept {X chromosome condensation}]