Trichorhinophalangeal syndrome (TRPS) comprises TRPS I (caused by a heterozygous pathogenic variant in TRPS1) and TRPS II (caused by contiguous gene deletion of TRPS1, RAD21, and EXT1). Both types of TRPS are characterized by distinctive facial features; ectodermal features (fine, sparse, depigmented, and slow growing hair; dystrophic nails; and small breasts); and skeletal findings (short stature; short feet; brachydactyly with ulnar or radial deviation of the fingers; and early, marked hip dysplasia). TRPS II is characterized by multiple osteochondromas (typically first observed clinically on the scapulae and around the elbows and knees between ages 1 month and 6 years) and an increased risk of mild-to-moderate intellectual disability.

Adult Refsum disease (ARD is associated with elevated plasma phytanic acid levels, late childhood-onset (or later) retinitis pigmentosa, and variable combinations of anosmia, polyneuropathy, deafness, ataxia, and ichthyosis. Onset of symptoms ranges from age seven months to older than age 50 years. Cardiac arrhythmia and heart failure caused by cardiomyopathy are potentially severe health problems that develop later in life.

An autosomal recessive subtype of cerebrooculofacioskeletal syndrome caused by mutation(s) in the ERCC6 gene, encoding DNA excision repair protein ERCC-6.

Aromatic L-amino acid decarboxylase deficiency (AADCD) is an autosomal recessive inborn error in neurotransmitter metabolism that leads to combined serotonin and catecholamine deficiency (Abeling et al., 2000). The disorder is clinically characterized by vegetative symptoms, oculogyric crises, dystonia, and severe neurologic dysfunction, usually beginning in infancy or childhood (summary by Brun et al., 2010).

Inherited congenital microcoria, also referred to as congenital miosis, is characterized by bilateral small pupils (diameter less than 2 mm) that result from an underdevelopment of the dilator pupillae muscle of the iris (Holth and Berner, 1923; Simpson and Parsons, 1989). Iris transillumination defects are a constant feature. The pupil dilates poorly or not at all in response to topically administered mydriatic drugs. The disorder is transmitted as an autosomal dominant trait with complete penetrance and is associated with goniodysgenesis and glaucoma (Tawara and Inomata, 1983; Mazzeo et al., 1986; Toulemont et al., 1995).

Total ophthalmoplegia involves total paralysis of all extra- and intraocular muscles. If one or more of the external muscles, including the levator palpebrae, is not affected, the condition is known as incomplete or partial ophthalmoplegia. If only 1 nerve is affected, the palsy is named after that nerve (see, e.g., abducens palsy, 100200) (Waardenburg, 1963).

Stormorken syndrome is an autosomal dominant disorder characterized by mild bleeding tendency due to platelet dysfunction, thrombocytopenia, anemia, asplenia, tubular aggregate myopathy, congenital miosis, and ichthyosis. Additional features may include headache or recurrent stroke-like episodes (summary by Misceo et al., 2014).

The Headache Classification Committee of the International Headache Society (1988) listed the following criteria for cluster headache (CH): at least 5 attacks of severe unilateral orbital, supraorbital, and/or temporal pain, lasting 15 to 180 minutes, associated with at least 1 of 8 local autonomic signs, and occurring once every other day to 8 per day. Approximately 85% of CH patients have the episodic subtype, in which the headaches occur in cluster periods lasting from 7 days to 1 year and separated by attack-free intervals of 1 month or more. The remainder of patients have the chronic subtype, in which attacks recur for greater than 1 year without remission or with remissions lasting less than 1 month (Lipton et al., 2004).

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).

Neuronal intranuclear inclusion disease (NIID) is an autosomal dominant, slowly progressive neurodegenerative disorder characterized by a wide range of clinical manifestations, including pyramidal and extrapyramidal symptoms, cerebellar ataxia, cognitive decline and dementia, peripheral neuropathy, and autonomic dysfunction. The age at onset varies, but most individuals present as adults between about 30 and 70 years of age. Pathologic investigation shows eosinophilic intranuclear inclusions in almost all cell types, including neurons, skin cells, fibroblasts, and skeletal muscle. Brain imaging shows a characteristic leukoencephalopathy with high intensity signals in the corticomedullary junction on diffusion-weighted imaging (DWI), as well as white matter abnormalities in subcortical and brainstem regions. Skin biopsy combined with brain imaging is useful for diagnosis (summary by Sone et al., 2016). The phenotype in some cases is suggestive of Parkinson disease (see 168600) and/or Alzheimer disease (see 104300), consistent with an evolving phenotypic spectrum of adult-onset NIID (summary by Tian et al., 2019).

RAB18 deficiency is the molecular deficit underlying both Warburg micro syndrome (characterized by eye, nervous system, and endocrine abnormalities) and Martsolf syndrome (characterized by similar – but milder – findings). To date Warburg micro syndrome comprises >96% of reported individuals with genetically defined RAB18 deficiency. The hallmark ophthalmologic findings are bilateral congenital cataracts, usually accompanied by microphthalmia, microcornea (diameter <10), and small atonic pupils. Poor vision despite early cataract surgery likely results from progressive optic atrophy and cortical visual impairment. Individuals with Warburg micro syndrome have severe to profound intellectual disability (ID); those with Martsolf syndrome have mild to moderate ID. Some individuals with RAB18 deficiency also have epilepsy. In Warburg micro syndrome, a progressive ascending spastic paraplegia typically begins with spastic diplegia and contractures during the first year, followed by upper-limb involvement leading to spastic quadriplegia after about age five years, often eventually causing breathing difficulties. In Martsolf syndrome infantile hypotonia is followed primarily by slowly progressive lower-limb spasticity. Hypogonadism – when present – manifests in both syndromes, in males as micropenis and/or cryptorchidism and in females as hypoplastic labia minora, clitoral hypoplasia, and small introitus.

Any tubular aggregate myopathy in which the cause of the disease is a mutation in the ORAI1 gene.

A rare genetic eye disease with characteristics of optic disc anomalies (bilateral colobomatous optic discs, retinal vessels arising from the peripheral optic disc) and macular atrophy. Peripapillary chorioretinal atrophy and chorioretinal and iris coloboma have also been described. Patients present with horizontal nystagmus and poor visual acuity.

Isolated congenital megalocornea is a genetic, non-syndromic developmental defect of the anterior eye segment. The disease has characteristics of bilateral enlargement of the corneal diameter and a deep anterior eye chamber, without an elevation in intraocular pressure. It can manifest with mild to moderate myopia as well as photophobia and iridodonesis (due to iris hypoplasia). Associated complications include lens dislocation, retinal detachment, presenile cataract development and secondary glaucoma. There is evidence this disease is caused by mutation in the CHRDL1 gene on chromosome Xq23.

Cataract-48 (CTRCT48) is characterized by infantile or early-childhood cataracts and visual impairment (Ansar et al., 2018).

Oculopharyngodistal myopathy-3 (OPDM3) is a neuromyodegenerative disease characterized by progressive muscle weakness with ocular, facial, pharyngeal, and distal limb involvement, resulting in dysarthria and gait difficulties. The onset of the disorder is usually in adulthood, although childhood onset has rarely been reported. Additional features include hyporeflexia, proximal muscle weakness, neck muscle weakness, dysarthria, dysphagia, and ptosis. Some patients may develop pigmentary retinopathy, peripheral neuropathy, or hearing loss. Cognition is usually not affected, but there may be deficits or psychiatric manifestations. Brain imaging tends to show a leukoencephalopathy, often with a characteristic linear signal along the corticomedullary junction on brain imaging. Skin and muscle biopsy show intranuclear inclusions and rimmed vacuoles. Many of the clinical features are reminiscent of NIID, suggesting that these disorders likely fall within a broad phenotypic spectrum of diseases with neuromyodegenerative features associated with abnormal repeat expansions in this gene (summary by Ogasawara et al., 2020 and Yu et al., 2021). For a discussion of genetic heterogeneity of OPDM, see OPDM1 (164310).