Silver-Russell Syndrome - 11p15 Imprinting Growth Restriction

A 4-year-old girl is referred to pediatrics with severe growth restriction (weight and height both <3rd centile despite adequate nutrition), relative macrocephaly with a triangular face, body asymmetry (left leg 2 cm shorter than right), and feeding difficulties. Her parents are of normal stature with no family history of growth disorders. Molecular testing reveals loss of methylation at the imprinting control region (IC1) on chromosome 11p15. The clinical and molecular findings shown in the diagram at **A** are consistent with Silver-Russell Syndrome. Which of the following best explains the mechanism of growth restriction in this patient's condition?