Beckwith-Wiedemann syndrome (BWS) is a growth disorder variably characterized by macroglossia, hemihyperplasia, omphalocele, neonatal hypoglycemia, macrosomia, embryonal tumors (e.g., Wilms tumor, hepatoblastoma, neuroblastoma, and rhabdomyosarcoma), visceromegaly, adrenocortical cytomegaly, kidney abnormalities (e.g., medullary dysplasia, nephrocalcinosis, and medullary sponge kidney), and ear creases / posterior helical ear pits. BWS is considered a clinical spectrum, in which affected individuals may have many or only one or two of the characteristic clinical features. Although most individuals with BWS show rapid growth in late fetal development and early childhood, growth rate usually slows by age seven to eight years. Adult heights are typically within the normal range. Hemihyperplasia (also known as lateralized overgrowth) is often appreciated at birth and may become more or less evident over time. Hemihyperplasia may affect segmental regions of the body or selected organs and tissues. Hemihyperplasia may be limited to one side of the body (ipsilateral) or involve opposite sides of the body (contralateral). Macroglossia is generally present at birth and can obstruct breathing or interfere with feeding in infants. Neonatal hypoglycemia occurs in approximately 50% of infants with BWS; most episodes are mild and transient. However, in some cases, persistent hypoglycemia due to hyperinsulinism may require consultation with an endocrinologist for therapeutic intervention. With respect to the increased risk for embryonal tumor development, the risk for Wilms tumor appears to be concentrated in the first seven years of life, whereas the risk for developing hepatoblastoma is concentrated in the first three to four years of life. Cognitive and neurobehavioral development is usually normal. After childhood, prognosis is generally favorable, although some adults experience issues requiring medical management (e.g., for renal or skeletal concerns).

Simpson-Golabi-Behmel syndrome type 1 (SGBS1) is characterized by pre- and postnatal macrosomia; distinctive craniofacial features (including macrocephaly, coarse facial features, macrostomia, macroglossia, and palate abnormalities); and, commonly, mild-to-severe intellectual disability with or without structural brain anomalies. Other variable findings include supernumerary nipples, diastasis recti / umbilical hernia, congenital heart defects, diaphragmatic hernia, genitourinary defects, and gastrointestinal issues. Skeletal anomalies can include vertebral fusion, scoliosis, rib anomalies, and congenital hip dislocation. Hand anomalies can include large hands and postaxial polydactyly. Affected individuals are at increased risk for embryonal tumors including Wilms tumor, hepatoblastoma, adrenal neuroblastoma, gonadoblastoma, hepatocellular carcinoma, and medulloblastoma.

Rubinstein-Taybi syndrome (RSTS) is characterized by distinctive facial features, broad and often angulated thumbs and halluces, short stature, and moderate-to-severe intellectual disability. Characteristic craniofacial features include downslanted palpebral fissures, low-hanging columella, high palate, grimacing smile, and talon cusps. Prenatal growth is often normal, then height, weight, and head circumference percentiles rapidly drop in the first few months of life. Short stature is typical in adulthood. Obesity may develop in childhood or adolescence. Average IQ ranges between 35 and 50; however, developmental outcome varies considerably. Some individuals with EP300-related RSTS have normal intellect. Additional features include ocular abnormalities, hearing loss, respiratory difficulties, congenital heart defects, renal abnormalities, cryptorchidism, feeding problems, recurrent infections, and severe constipation.

Developmental and epileptic encephalopathy-114 (DEE114) is characterized by moderately to severely impaired intellectual development, onset of epilepsy within the first 18 months of life, and a choreiform, dystonic, or dyskinetic movement disorder (Platzer et al., 2022). For general phenotypic information and a discussion of genetic heterogeneity of DEE, see 308350.