Partial deletion of the short arm of chromosome 4 with severe psychomotor deficiency and abnormalities of the craniofacial structures, heart, kidneys, and other organs. The most common defects include asymmetric skull, microcephaly, high forehead, beaked nose, hypertelorism, epicanthal folds, and prominent glabella. The phenotype of proximal interstitial deletion (del4p15) differs from that in the Wolf-Hirschhorn syndrome and is characterized by distinct facies, multiple minor congenital anomalies, psychomotor retardation and normal growth. Deletion 4p15-16 is expressed in a different phenotype which includes long face, midface hypoplasia, upslanted palpebral fissures, epicanthal folds, large beaked nose, highly arched palate, thick lower lip, micrognathia, broad and short neck, broad hands and feet, tall and thin habitus, delayed growth and mental development, and hypotonia.