Familial cutaneous collagenoma is a connective tissue nevus characterized by multiple, flesh-colored asymptomatic nodules distributed symmetrically on the trunk and upper arms (mainly on the upper two-thirds of the back), manifesting around adolescence. The skin biopsy reveals an accumulation of collagen fibers with reduction in the number of elastic fibers. Cardiac anomalies may be observed. Familial cutaneous collagenoma follows an autosomal dominant mode of transmission.

Osteoporosis-pseudoglioma syndrome is a rare condition characterized by severe thinning of the bones (osteoporosis) and eye abnormalities that lead to vision loss. In people with this condition, osteoporosis is usually recognized in early childhood. It is caused by a shortage of minerals, such as calcium, in bones (decreased bone mineral density), which makes the bones brittle and prone to fracture. Affected individuals often have multiple bone fractures, including in the bones that form the spine (vertebrae). Multiple fractures can cause collapse of the affected vertebrae (compressed vertebrae), abnormal side-to-side curvature of the spine (scoliosis), short stature, and limb deformities. Decreased bone mineral density can also cause softening or thinning of the skull (craniotabes).\n\nMost affected individuals have impaired vision at birth or by early infancy and are blind by young adulthood. Vision problems are usually caused by one of several eye conditions, grouped together as pseudoglioma, that affect the light-sensitive tissue at the back of the eye (the retina), although other eye conditions have been identified in affected individuals. Pseudogliomas are so named because, on examination, the conditions resemble an eye tumor known as a retinal glioma.\n\nRarely, people with osteoporosis-pseudoglioma syndrome have additional signs or symptoms such as mild intellectual disability, weak muscle tone (hypotonia), abnormally flexible joints, or seizures.

Traboulsi syndrome is characterized by dislocated crystalline lenses and anterior segment abnormalities in association with a distinctive facies involving flat cheeks and a beaked nose. Some affected individuals develop highly unusual nontraumatic conjunctival cysts (filtering blebs), presumably caused by abnormal thinning of the sclera (Patel et al., 2014).

A posterior polymorphous corneal dystrophy that has material basis in autosomal dominant inheritance of mutation in the OVOL2 gene on chromosome 20p11.23.

Multiple system atrophy (MSA) is a distinct clinicopathologic entity that manifests as a progressive adult-onset neurodegenerative disorder causing parkinsonism, cerebellar ataxia, and autonomic, urogenital, and pyramidal dysfunction in various combinations. Two main subtypes are recognized: 'subtype C,' characterized predominantly by cerebellar ataxia, and 'subtype P,' characterized predominantly by parkinsonism. MSA is characterized pathologically by the degeneration of striatonigral and olivopontocerebellar structures and glial cytoplasmic inclusions (GCIs) that consist of abnormally phosphorylated alpha-synuclein (SNCA; 163890) or tau (MAPT; 157140) (Gilman et al., 1998; Gilman et al., 2008; Scholz et al., 2009). 'Subtype C' of MSA has been reported to be more prevalent than 'subtype P' in the Japanese population (65-67% vs 33-35%), whereas 'subtype P' has been reported to be more prevalent than 'subtype C' in Europe (63% vs 34%) and North America (60% vs 13%, with 27% of cases unclassified) (summary by The Multiple-System Atrophy Research Collaboration, 2013). MSA is similar clinically and pathologically to Parkinson disease (PD; 168600) and Lewy body dementia (127750). See also PARK1 (168601), which is specifically caused by mutation in the SNCA gene. Pure autonomic failure manifests as orthostatic hypotension and other autonomic abnormalities without other neurologic involvement. Although there is some phenotypic overlap, the relationship of pure autonomic failure to MSA is unclear (Vanderhaeghen et al., 1970; Schatz, 1996).

Neurooculorenal syndrome (NORS) is an autosomal recessive developmental disorder with highly variable clinical manifestations involving several organ systems. Some affected individuals present in utero with renal agenesis and structural brain abnormalities incompatible with life, whereas others present in infancy with a neurodevelopmental disorder characterized by global developmental delay and dysmorphic facial features that may be associated with congenital anomalies of the kidney and urinary tract (CAKUT). Additional more variable features may include ocular anomalies, most commonly strabismus, congenital heart defects, and pituitary hormone deficiency. Brain imaging usually shows structural midline defects, including dysgenesis of the corpus callosum and hindbrain. There is variation in the severity, manifestations, and expressivity of the phenotype, even within families (Rasmussen et al., 2018; Munch et al., 2022).

Retinitis pigmentosa-97 (RP97) is characterized by onset of night blindness and visual field defects in the first decade of life, with later onset of reduced visual acuity (Kong et al., 2023). For a general phenotypic description and a discussion of genetic heterogeneity of RP, see 268000.