Norrie disease (ND) is an X-linked recessive disorder characterized by very early childhood blindness due to degenerative and proliferative changes of the neuroretina. Approximately 50% of patients show some form of progressive mental disorder, often with psychotic features, and about one-third of patients develop sensorineural deafness in the second decade. In addition, some patients have more complex phenotypes, including growth failure and seizures (Berger et al., 1992). Warburg (1966) noted confusion of the terms 'pseudoglioma' and microphthalmia with Norrie disease in the literature. 'Pseudoglioma' is a nonspecific term for any condition resembling retinoblastoma and can have diverse causes, including inflammation, hemorrhage, trauma, neoplasia, or congenital malformation, and often shows unilateral involvement. Thus, 'pseudoglioma' is not an acceptable clinical or pathologic diagnosis (see Duke, 1958).

Microcephaly with or without chorioretinopathy, lymphedema, or impaired intellectual development (MCLMR) is an autosomal dominant disorder that involves an overlapping but variable spectrum of central nervous system and ocular developmental anomalies. Microcephaly ranges from mild to severe and is often associated with mild to moderate developmental delay and a characteristic facial phenotype with upslanting palpebral fissures, broad nose with rounded tip, long philtrum with thin upper lip, prominent chin, and prominent ears. Chorioretinopathy is the most common eye abnormality, but retinal folds, microphthalmia, and myopic and hypermetropic astigmatism have also been reported, and some individuals have no overt ocular phenotype. Congenital lymphedema, when present, is typically confined to the dorsa of the feet, and lymphoscintigraphy reveals the absence of radioactive isotope uptake from the webspaces between the toes (summary by Ostergaard et al., 2012). Robitaille et al. (2014) found that MCLMR includes a broader spectrum of ocular disease, including retinal detachment with avascularity of the peripheral retina, and noted phenotypic overlap with familial exudative vitreoretinopathy (FEVR; see EVR1, 133780). Birtel et al. (2017) observed intrafamilial and intraindividual variability in retinal phenotype, and noted that syndromic manifestations in some patients are too subtle to be detected during a routine ophthalmologic evaluation. Variable expressivity and reduced penetrance have also been observed in some families (Jones et al., 2014; Li et al., 2016). Autosomal recessive forms of microcephaly with chorioretinopathy have been reported (see 251270). See also Mirhosseini-Holmes-Walton syndrome (autosomal recessive microcephaly with pigmentary retinopathy and impaired intellectual development; 268050).

Familial exudative vitreoretinopathy (FEVR) is an inherited disorder characterized by the incomplete development of the retinal vasculature. Its clinical appearance varies considerably, even within families, with severely affected patients often registered as blind during infancy, whereas mildly affected patients with few or no visual problems may have such a small area of avascularity in their peripheral retina that it is visible only by fluorescein angiography. It is believed that this peripheral avascularity is the primary anomaly in FEVR and results from defective retinal angiogenesis. The sight-threatening features of the FEVR phenotype are considered secondary to retinal avascularity and develop because of the resulting retinal ischemia; they include the development of hyperpermeable blood vessels, neovascularization, vitreoretinal traction, retinal folds, and retinal detachments (summary by Poulter et al., 2010). For a discussion of genetic heterogeneity of FEVR, see EVR1 (133780).

Familial exudative vitreoretinopathy (FEVR) is an inherited disorder characterized by the incomplete development of the retinal vasculature. Its clinical appearance varies considerably, even within families, with severely affected patients often registered as blind during infancy, whereas mildly affected patients with few or no visual problems may have such a small area of avascularity in their peripheral retina that it is visible only by fluorescein angiography. It is believed that this peripheral avascularity is the primary anomaly in FEVR and results from defective retinal angiogenesis. The sight-threatening features of the FEVR phenotype are considered secondary to retinal avascularity and develop because of the resulting retinal ischemia; they include the development of hyperpermeable blood vessels, neovascularization, vitreoretinal traction, retinal folds, and retinal detachments (summary by Poulter et al., 2010). For a discussion of genetic heterogeneity of familial exudative vitreoretinopathy, see EVR1 (133780).

Distal arthrogryposis type 5 is distinguished from other forms of DA by the presence of ocular abnormalities, typically ptosis, ophthalmoplegia, and/or strabismus, in addition to contractures of the skeletal muscles. Some cases have been reported to have pulmonary hypertension as a result of restrictive lung disease (summary by Bamshad et al., 2009). There are 2 syndromes with features overlapping those of DA5 that are also caused by heterozygous mutation in PIEZO2: distal arthrogryposis type 3 (DA3, or Gordon syndrome; 114300) and Marden-Walker syndrome (MWKS; 248700), which are distinguished by the presence of cleft palate and mental retardation, respectively. McMillin et al. (2014) suggested that the 3 disorders might represent variable expressivity of the same condition. For a general phenotypic description and a discussion of genetic heterogeneity of distal arthrogryposis, see DA1A (108120). Genetic Heterogeneity of Distal Arthrogryposis 5 A subtype of DA5 due to mutation in the ECEL1 gene (605896) on chromosome 2q36 has been designated DA5D (615065). See NOMENCLATURE.

Persistent hyperplastic primary vitreous (PHPV), also termed 'persistent fetal vasculature,' is a developmental malformation of the eye in which the primary vitreous fails to regress in utero, resulting in the presence of a retrolental fibrovascular membrane with persistence of the posterior portion of the tunica vasculosa lentis and hyaloid artery. This abnormality is usually unilateral and associated with microphthalmia, cataract, glaucoma, and congenital retinal nonattachment (see Haddad et al., 1978; Khaliq et al., 2001; Prasov et al., 2012). PHPV shares phenotypic overlap with Norrie disease (310600). Genetic Heterogeneity of Persistent Hyperplastic Primary Vitreous A dominant form of PHPV has been described (PHPVAD; 611308).

Autosomal recessive isolated posterior microphthalmos defines a rare distinct phenotype restricted to the posterior segment of the eye. In adults, it is clinically characterized by extreme hyperopia (from +7.5 to +21 diopters) due to short axial length (14 mm to 20 mm; normal is greater than 21 mm). Other features include an essentially normal anterior segment, steep corneal curvatures, shallow anterior chamber, thick lenses, and thickened scleral wall. The palpebral fissures appear narrow because of relatively deep-set eyes, visual acuity is mildly to moderately reduced, and anisometropic or strabismic amblyopia is common. The fundus of the eye shows crowded optical discs, tortuous vessels, and an abnormal foveal avascular zone; in addition, papillomacular folds are often reported. Morphometric features of the small eyes predispose to complications such as narrow-angle glaucoma and uveal effusion (summary by Gal et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of isolated microphthalmia, see MCOP1 (251600).

Microcephaly and chorioretinopathy is an autosomal recessive developmental disorder characterized by delayed psychomotor development and visual impairment, often accompanied by short stature (summary by Martin et al., 2014). Genetic Heterogeneity of Microcephaly and Chorioretinopathy See also MCCRP2 (616171), caused by mutation in the PLK4 gene (605031) on chromosome 4q27, and MCCRP3 (616335), caused by mutation in the TUBGCP4 gene (609610) on chromosome 15q15. An autosomal dominant form of microcephaly with or without chorioretinopathy, lymphedema, or impaired intellectual development is caused by heterozygous mutation in the KIF11 gene (148760) on chromosome 10q23. See also Mirhosseini-Holmes-Walton syndrome (autosomal recessive pigmentary retinopathy and mental retardation; 268050).