JABL: Increased birth weight with excessive growth during the first four years of life, macrocephaly, characteristic facial features, nonprogressive cerebral disorder and mental retardation.,NCI: A rare genetic syndrome caused by mutations in the NSD1 gene. It is characterized by excessive physical growth early in life, mild mental retardation, and delayed cognitive and social development. Children affected by this syndrome are tall with larger than normal heads.,MSH: Congenital or postnatal overgrowth syndrome most often in height and occipitofrontal circumference with variable delayed motor and cognitive development. Other associated features include advanced bone age, seizures, NEONATAL JAUNDICE; HYPOTONIA; and SCOLIOSIS. It is also associated with increased risk of developing neoplasms in adulthood. Mutations in the NSD1 protein and its HAPLOINSUFFICIENCY are associated with the syndrome.