Question

Unbearable Cuteness is a condition that results from mutations in the gene CuteEnough (an imprinted gene). The promoter of the maternal allele of CuteEnough becomes methylated during gametogenesis while that of the paternal allele remains unmethylated. Can Unbearable Cuteness be caused by mutations in the coding region of the maternal allele of CuteEnough? How about mutations in the coding region of the paternal allele? Provide an explanation for your answer.

Answer 1

DNA methylation is a biological process where methyl groups are added at DNA bases, particularly at CpG island of DNA. DNA methylation at the promoter generally cause repression of a gene. Promoter, if remain methylated, RNA polymerase and other transcription factors cannot bind to the promoter region and therefore the gene remain turned off. So if mother's cute enough gene promoter became methylated, mutation in the coding region probably do not cause Unbearable Cuteness phenotype as cuteEnough gene will not be transcribed. As the paternal Cute Enough gene promoter is not methylated, particular mutation in the coding region may transform Cute Enough gene into Unbearable Cuteness phenotype.