Genomic Imprinting

Some genes are methylated according to parent of origin. Only one allele is expressed.

“The goal is not to methylate everything. The goal is to regulate the right genes, in the right tissues, at the right time, at the right intensity.”

IGF2 / H19 (11p15.5)

Maternal

IGF2

SILENCED (methylated)

Paternal

IGF2

EXPRESSED (active)

Methylation on the paternal ICR1 silences H19 and lets IGF2 be expressed only from the father's allele.

Imprinting is like a 'tag' that says which copy of the gene should work — dad's or mom's. When the tag is lost, very specific diseases appear.