Cleft palate as an isolated malformation behaves as an entity distinct from cleft lip with or without cleft palate (see 119530). Dominantly inherited cleft soft palate in 4 generations has been reported (Jenkins and Stady, 1980); see 119570.

Spinocerebellar ataxia-29 (SCA29) is an autosomal dominant neurologic disorder characterized by onset in infancy of delayed motor development and mild cognitive delay. Affected individuals develop a very slowly progressive or nonprogressive gait and limb ataxia associated with cerebellar atrophy on brain imaging. Additional variable features include nystagmus, dysarthria, and tremor (summary by Huang et al., 2012). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).

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. The characteristic craniofacial features are 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-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.

Amelogenesis imperfecta is an inherited defect of dental enamel formation that shows both clinical and genetic heterogeneity. In the hypoplastic type of AI, the enamel is of normal hardness but does not develop to normal thickness. The thinness of the enamel makes the teeth appear small. Radiographically, enamel contrasts normally from dentin. The surface of the enamel can vary, showing smooth, rough, pitted, or local forms (Witkop, 1988).

HIVEP2-related intellectual disability is a neurological disorder characterized by moderate to severe developmental delay and intellectual disability and mild physical abnormalities (dysmorphic features). Early symptoms of the condition include weak muscle tone (hypotonia) and delayed development of motor skills, such as sitting, standing, and walking. After learning to walk, many affected individuals continue to have difficulty with this activity; their walking style (gait) is often unbalanced and wide-based. Speech is also delayed, and some people with this condition never learn to talk. Most people with HIVEP2-related intellectual disability also have unusual physical features, such as widely spaced eyes (hypertelorism), a broad nasal bridge, or fingers with tapered ends, although there is no characteristic pattern of such features among affected individuals. Many people with the condition exhibit neurodevelopmental disorders, such as hyperactivity, attention deficit disorder, aggression, anxiety, and autism spectrum disorder, which is a group of developmental disorders characterized by impaired communication and social interaction.\n\nOther features of HIVEP2-related intellectual disability include mild abnormalities in the structure of the brain and an abnormally small brain and head size (microcephaly). Less common health problems include seizures; recurrent ear infections; and eye disorders, such as eyes that do not look in the same direction (strabismus), "lazy eye" (amblyopia), and farsightedness (hyperopia). Some people with HIVEP2-related intellectual disability have gastrointestinal problems, which can include backflow of acidic stomach contents into the esophagus (gastroesophageal reflux) and constipation.

Branchiootorenal spectrum disorder (BORSD) is characterized by malformations of the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment, branchial fistulae and cysts, and renal malformations ranging from mild renal hypoplasia to bilateral renal agenesis. Some individuals progress to end-stage renal disease (ESRD) later in life. Extreme variability can be observed in the presence, severity, and type of branchial arch, otologic, audiologic, and renal abnormality from right side to left side in an affected individual and also among individuals in the same family.

CATIFA syndrome is characterized by global developmental delay and impaired intellectual development ranging from mild to severe, with most patients exhibiting attention-deficit hyperactivity disorder (ADHD). Patients show an elongated face with long philtrum and small ears. Ocular anomalies include congenital cataracts, strabismus, and amblyopia, which may be associated with reduced vision; other anomalies include cleft lip and/or palate and misaligned teeth with extensive caries (Unlu et al., 2020).

Carey-Fineman-Ziter syndrome-2 (CFZS2) is an autosomal recessive disorder characterized by weakness of the facial musculature, hypomimic facies, increased overbite, micrognathia, and facial dysmorphism. Other features may include failure to thrive, axial hypotonia, and progressive scoliosis (Ramirez-Martinez et al., 2022). For a discussion of genetic heterogeneity of Carey-Fineman-Ziter syndrome, see CFZS1 (254940).

Autosomal dominant intellectual developmental disorder-73 (MRD73) is a highly variable neurodevelopmental disorder characterized by impaired intellectual development that ranges from mild to severe, speech delay, behavioral abnormalities, and nonspecific dysmorphic facial features (Janssen et al., 2022).

Neuroocular syndrome-1 (NOC1) encompasses a broad spectrum of overlapping anomalies, with developmental delay or impaired intellectual development as a consistent finding. Eye abnormalities show marked variability in the type and severity of defects, and include anophthalmia, microphthalmia, and coloboma. Other common systemic features include congenital heart and kidney defects, hypotonia, failure to thrive, and microcephaly (summary by Chowdhury et al., 2021). Genetic Heterogeneity of Neuroocular Syndrome See also NOC2 (168885), caused by mutation in the DAGLA gene (614015) on chromosome 11q12.