Overgrowth

Abstract

This chapter reviews information on disorders that cause large birth weight, macrosomia, and/or segmental overgrowth. The most common of these conditions is seen in infants of diabetic mothers. Abnormal dosage of growth regulating genes make chromosomal microarray abnormalities a relatively common cause of overgrowth. Particularly notable is the distinctive Pallister Killian syndrome (12p tetrasomy). Other common overgrowth syndromes include Beckwith-Wiedemann syndrome, Sotos, Malan, and Weaver syndromes. The RASopathy syndromes including Noonan syndrome* and Costello syndrome are also often large at birth. Segmental overgrowth syndromes including Proteus and Klippel Trenaunay as well as PIK3CA related overgrowth (PROS) are discussed as well as their somatic mosaic origin in affected tissues. Clinical guidelines for evaluation and surveillance are outlined. The clinical case presentation features an infant with Sotos syndrome.