Beckwith-Wiedemann syndrome (BWS) is a congenital growth disorder, which means it’s present at birth. BWS has various signs and symptoms, including a large body size at birth and taller-than-average height during childhood, a large tongue, and hypoglycemia (low blood sugar). In some children with BWS, parts of the body, such as the ears, may grow abnormally large, leading to an asymmetric or uneven appearance. This unusual growth, known as hemihyperplasia, usually begins to slow by age 8. BWS can also lead to an increased risk of certain childhood cancers, most commonly Wilms tumor (kidney tumor) and hepatoblastoma (liver tumor).