GLI3-related Pallister-Hall syndrome (GLI3-PHS) is characterized by a spectrum of anomalies ranging from polydactyly, asymptomatic bifid epiglottis, and hypothalamic hamartoma at the mild end to laryngotracheal cleft with neonatal lethality at the severe end. Individuals with mild GLI3-PHS may be incorrectly diagnosed as having isolated postaxial polydactyly type A. Individuals with GLI3-PHS can have pituitary insufficiency and may die as neonates from undiagnosed and untreated adrenal insufficiency.

MID1-related Opitz G/BBB syndrome (MID1-OS) is characterized by facial anomalies (hypertelorism, prominent forehead, widow's peak, broad nasal bridge, anteverted nares), genitourinary abnormalities (hypospadias, cryptorchidism, and hypoplastic/bifid scrotum), and laryngotracheoesophageal defects. Developmental delay and intellectual disability are observed in about 30% of affected males. Cleft lip and/or palate are present in approximately half of affected males. Other malformations (present in <50% of affected males) include congenital heart defects, imperforate or ectopic anus, and midline brain defects (Dandy-Walker malformation and agenesis or hypoplasia of the corpus callosum and/or cerebellar vermis). Wide clinical variability occurs even among members of the same family. Female heterozygotes usually manifest hypertelorism only.

Auriculocondylar syndrome (ARCND) is a rare craniofacial disorder involving first and second pharyngeal arch derivatives and includes the key features of micrognathia, temporomandibular joint and condyle anomalies, microstomia, prominent cheeks, and question mark ears (QMEs). QMEs consist of a defect between the lobe and the upper two-thirds of the pinna, ranging from a mild indentation in the helix to a complete cleft between the lobe and helix (summary by Gordon et al., 2013). For a general phenotypic description and discussion of genetic heterogeneity of auriculocondylar syndrome, see ARCND1 (602483).

Chung-Jansen syndrome (CHUJANS) is characterized by global developmental delay apparent from infancy, impaired intellectual development or learning difficulties, behavioral abnormalities, dysmorphic features, and obesity. The severity of the phenotype and additional features are variable (summary by Jansen et al., 2018).

Oculogastrointestinal neurodevelopmental syndrome (OGIN) is characterized by microphthalmia and/or coloboma in association with other congenital anomalies, including imperforate anus, horseshoe kidney, and structural cardiac defects. Hearing loss and severe developmental delay are also observed in most patients (Zha et al., 2020; Mor-Shaked et al., 2021).

Developmental delay, impaired speech, and behavioral abnormalities (DDISBA) is characterized by global developmental delay apparent from early childhood. Intellectual disability can range from mild to severe. Additional variable features may include dysmorphic facial features, seizures, hypotonia, motor abnormalities such as Tourette syndrome or dystonia, and hearing loss (summary by Cousin et al., 2021).

Developmental delay, hypotonia, and impaired language (DEDHIL) is a neurodevelopmental disorder characterized by variably impaired intellectual development usually with hypotonia, mild motor delay, and language difficulties. Affected individuals may also have nonspecific dysmorphic facial features, gastrointestinal problems, and abnormalities on brain imaging (Stephenson et al., 2022).