GRB10 and fetal growth restriction: As described for IUGR, PNGR in case of GRB10 duplications might also be explained by an increase of GRB10 dosage [23], but due to its biallelic expression in many human tissues this explanation might not be apply for the molecular disturbances which silence the paternal allele (upd(7)mat, deletion or GOM of GRB10).