DNTT and microcephaly: However, contrary to our expectation of a cortical overgrowth phenotype due to Cdkn1c loss of function, and RGP equipotency with G/R of 1, we observed a dramatic reduction of GFP+Cdkn1c−/− matUPD cells when compared to tdT+Cdkn1c+/+ patUPD (although with two copies of silenced Cdkn1c) and severe microcephaly (Fig. 3c–f).