Patients with mutations in the receptor for insulin-like growth factor I exhibit intrauterine growth retardation, postnatal growth failure, short stature, and microcephaly. Additional features may include delayed bone age, developmental delay, and dysmorphic features. Insulin-like growth factor I deficiency (IGF1D) is characterized by severe pre- and postnatal growth failure, sensorineural deafness, and impaired motor and intellectual development. This disorder is also marked by increased plasma IGF1 levels. It is an autosomal recessive condition that presents with growth retardation, sensorineural deafness, and intellectual disability.