Congenital hypotrichosis with juvenile macular dystrophy (HJMD) is an autosomal recessive disorder characterized by hair loss followed by progressive macular degeneration and early blindness. Scalp hair is lost during the first months of life, with onset of retinal degeneration and vision loss a few years to 2 decades later (summary by Sprecher et al., 2001 and Indelman et al., 2002).

Any retinitis pigmentosa in which the cause of the disease is a mutation in the NRL gene.

There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body.\n\nThe first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus).\n\nCone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.

Cone dystrophy with supernormal rod responses (CDSRR) is characterized by onset in the first or second decade of life of very marked photophobia, myopia, reduced color vision along the red-green axis with relatively preserved tritan discrimination, and central scotomata with peripheral widespread sensitivity loss predominating in the superior visual field. Nyctalopia is a later feature of the disorder. There is often retinal pigment epithelium disturbance at the macula with a normal retinal periphery. Autofluorescence (AF) imaging shows either a perifoveal ring or a central macular area of relative increased AF (summary by Michaelides et al., 2005).

Spondylometaphyseal dysplasia with cone-rod dystrophy (SMDCRD) is characterized by postnatal growth deficiency resulting in profound short stature, rhizomelia with bowing of the lower extremities, platyspondyly with anterior vertebral protrusions, progressive metaphyseal irregularity and cupping with shortened tubular bones, and early-onset progressive visual impairment associated with a pigmentary maculopathy and electroretinographic evidence of cone-rod dysfunction (summary by Hoover-Fong et al., 2014). Yamamoto et al. (2014) reviewed 16 reported cases of SMDCRD, noting that all affected individuals presented uniform skeletal findings, with rhizomelia and bowed lower limbs observed in the first year of life, whereas retinal dystrophy had a more variable age of onset. There was severe disproportionate short stature, with a final height of less than 100 cm; scoliosis was usually mild. Visual loss was progressive, with stabilization in adolescence.

Early-onset neurodegeneration in the human retina can lead to Leber congenital amaurosis (LCA), the most severe human form of inherited photoreceptor-neuron degeneration resulting in congenital blindness, with an incidence of approximately 1 in 80,000 (summary by Koenekoop et al., 2012). NMNAT1 mutations have been observed to cause severe and rapidly progressive macular degeneration, leading to severe central atrophy with an appearance of congenital macular coloboma in the neonatal period, as well as an unusual early-onset atrophy of the optic nerve (Perrault et al., 2012). Some patients present with later onset and milder phenotype than typical LCA (Kumaran et al., 2021). For a general discussion of the phenotypic and genetic heterogeneity in Leber congenital amaurosis, see LCA1 (204000).

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of retinal dystrophies characterized by a progressive degeneration of photoreceptors, eventually resulting in severe visual impairment. For a discussion of genetic heterogeneity of RP, see 268000.

Stargardt disease-3 (STGD3) is an autosomal dominant juvenile macular dystrophy with onset most commonly in the second decade of life. Fundus examination reveals macular pigmentary changes and yellow flecks. Fluorescein angiography shows macular retinal pigment epithelium (RPE) defects (Bernstein et al., 2001; Maugeri et al., 2004).

Adult-onset foveomacular vitelliform dystrophy, also known as adult vitelliform macular dystrophy, adult-type foveomacular dystrophy, adult vitelliform macular degeneration, pseudovitelliform macular degeneration, and adult-onset foveomacular pigment epithelial dystrophy, is characterized by a solitary, oval, slightly elevated yellowish subretinal lesion of the fovea that is similar in appearance to the vitelliform or egg-yolk stage of Best disease (153700). Initially the yellow lesion may be present in only one eye. The size is generally one-third to one disc diameter, and small yellow flecks are seen in the paracentral lesion. Patients usually become symptomatic in the fourth or fifth decade of life with a protracted decrease of visual acuity and mild metamorphopsia. Electrooculographic testing reveals a normal or only slightly reduced Arden ratio, which is intensely abnormal in Best disease. The prognosis is optimistic, as most patients retain reading vision throughout life (Felbor et al., 1997; Yamaguchi et al., 2001). For a discussion of genetic heterogeneity of vitelliform macular dystrophy, see VMD1 (153840).

With the current widespread use of multigene panels and comprehensive genomic testing, it has become apparent that the phenotypic spectrum of EPG5-related disorder represents a continuum. At the most severe end of the spectrum is classic Vici syndrome (defined as a neurodevelopmental disorder with multisystem involvement characterized by the combination of agenesis of the corpus callosum, cataracts, hypopigmentation, cardiomyopathy, combined immunodeficiency, microcephaly, and failure to thrive); at the milder end of the spectrum are attenuated neurodevelopmental phenotypes with variable multisystem involvement. Median survival in classic Vici syndrome appears to be 24 months, with only 10% of children surviving longer than age five years; the most common causes of death are respiratory infections as a result of primary immunodeficiency and/or cardiac insufficiency resulting from progressive cardiac failure. No data are available on life span in individuals at the milder end of the spectrum.

Autosomal recessive childhood-onset severe retinal dystrophy is a heterogeneous group of disorders affecting rod and cone photoreceptors simultaneously. The most severe cases are termed Leber congenital amaurosis (LCA), whereas the less aggressive forms are usually considered juvenile retinitis pigmentosa (Gu et al., 1997). Various intermediate phenotypes between LCA and retinitis pigmentosa are known and are sometimes described as 'early-onset severe rod-cone dystrophy' or 'early-onset retinal degeneration' (Booij et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of Leber congenital amaurosis, see LCA1 (204000); for retinitis pigmentosa, see 268000; for cone-rod dystrophy, see 120970.

Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.\n\nThe first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus).\n\nThere are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body.

Colobomatous macrophthalmia with microcornea (MACOM) is an autosomal dominant eye malformation characterized by microcornea with increased axial length, coloboma of the iris and optic disc, and severe myopia (summary by Beleggia et al., 2015).

Progressive cone dystrophy usually presents in childhood or early adult life, with many patients developing rod photoreceptor involvement in later life, thereby leading to considerable overlap between progressive cone dystrophy and cone-rod dystrophy. Both progressive cone dystrophy and cone-rod dystrophy have been associated with mutation in the GUCA1A gene (Michaelides et al., 2006). Intrafamilial variability in GUCA1A-associated macular disease ranges from mild photoreceptor degeneration to central areolar choroidal dystrophy (CACD), a form of retinal degeneration that primarily involves the macula and is characterized by a well-defined atrophic region of retinal pigment epithelium and choriocapillaris in the latest stage (Chen et al., 2017).

There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body.\n\nThe first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus).\n\nCone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.

Autosomal dominant retinitis pigmentosa (ADRP) is characterized by a typical fundus appearance, narrowed retinal vessels, and changes in the electrophysiological responses of the eye. Early signs are night blindness and constriction of the visual fields with a variable ages of onset (summary by Jay et al., 1992).

Gaucher disease (GD) encompasses a continuum of clinical findings from a perinatal lethal disorder to an asymptomatic type. The identification of three major clinical types (1, 2, and 3) and two other subtypes (perinatal-lethal and cardiovascular) is useful in determining prognosis and management. GD type 1 is characterized by the presence of clinical or radiographic evidence of bone disease (osteopenia, focal lytic or sclerotic lesions, and osteonecrosis), hepatosplenomegaly, anemia and thrombocytopenia, lung disease, and the absence of primary central nervous system disease. GD types 2 and 3 are characterized by the presence of primary neurologic disease; in the past, they were distinguished by age of onset and rate of disease progression, but these distinctions are not absolute. Disease with onset before age two years, limited psychomotor development, and a rapidly progressive course with death by age two to four years is classified as GD type 2. Individuals with GD type 3 may have onset before age two years, but often have a more slowly progressive course, with survival into the third or fourth decade. The perinatal-lethal form is associated with ichthyosiform or collodion skin abnormalities or with nonimmune hydrops fetalis. The cardiovascular form is characterized by calcification of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supranuclear ophthalmoplegia. Cardiopulmonary complications have been described with all the clinical subtypes, although varying in frequency and severity.

Syndrome with characteristics of progressive pigmentary retinal degeneration (with nyctalopia and visual field restriction), cystic macular degeneration and angle closure glaucoma. It has been described in seven members of one family. Patients also have hyperopia and nanophthalmos. The mode of transmission is autosomal recessive.

CSNB1D is an autosomal recessive form of congenital stationary night blindness that is characterized by a Riggs type of electroretinogram (proportionally reduced a- and b-waves). Patients with Riggs-type CSNB have visual acuity within the normal range and no symptoms of myopia and/or nystagmus (summary by Riazuddin et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of congenital stationary night blindness, see CSNB1A (310500).

Retinitis pigmentosa (RP) describes a group of disorders with progressive degeneration of rod and cone photoreceptors in a rod-cone pattern of dysfunction. RP has a prevalence of 1 in 3,500, and is genetically and phenotypically heterogeneous (summary by Mackay et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of retinitis pigmentosa, see 268000.

Cone-rod dystrophy (CORD) and retinitis pigmentosa (RP) are clinically and genetically overlapping heterogeneous retinal dystrophies. RP is characterized initially by rod photoreceptor dysfunction, giving rise to night blindness, which is followed by progressive rod and cone photoreceptor dystrophy, resulting in midperipheral vision loss, tunnel vision, and sometimes blindness. In contrast to RP, CORD is characterized by a primary loss of cone photoreceptors and subsequent or simultaneous loss of rod photoreceptors. The disease in most cases becomes apparent during primary-school years, and symptoms include photoaversion, decrease in visual acuity with or without nystagmus, color vision defects, and decreased sensitivity of the central visual field. Because rods are also involved, night blindness and peripheral vision loss can occur. The diagnosis of CORD is mainly based on electroretinogram (ERG) recordings, in which cone responses are more severely reduced than, or equally as reduced as rod responses (summary by Estrada-Cuzcano et al., 2012).

Jalili syndrome is an autosomal recessive disorder consisting of cone-rod dystrophy and amelogenesis imperfecta. Significant visual impairment with nystagmus and photophobia is present from infancy or early childhood and progresses with age. Enamel of primary and secondary dentitions is grossly abnormal and prone to rapid posteruptive failure, in part reflecting hypomineralization (summary by Parry et al., 2009).

X-linked congenital retinoschisis (XLRS) is characterized by symmetric bilateral macular involvement with onset in the first decade of life, in some cases as early as age three months. Fundus examination shows areas of schisis (splitting of the nerve fiber layer of the retina) in the macula, sometimes giving the impression of a spoke wheel pattern. Schisis of the peripheral retina, predominantly inferotemporally, occurs in approximately 50% of individuals. Affected males typically have 20/60 to 20/120 vision. Visual acuity often deteriorates during the first and second decades of life but then remains relatively stable until the fifth or sixth decade.

Bardet-Biedl syndrome-17 (BBS17) is an autosomal recessive ciliopathy characterized by retinitis pigmentosa, cognitive impairment, obesity, renal dysfunction, and hypogenitalism. Polydactyly, most often postaxial, is also a primary feature of BBS; in BBS17, mesoaxial polydactyly, with fused or Y-shaped metacarpals, is a distinct manifestation (Deffert et al., 2007; Schaefer et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of Bardet-Biedl syndrome, see BBS1 (209900).

BBS5 is a ciliopathy associated with severe and early-onset retinal dystrophy, postaxial polydactyly, obesity, renal dysfunction, hypogonadism, and learning difficulties (summary by Scheidecker et al., 2015). Patients described by Young et al. (1999) and Moore et al. (2005) with mutations in the BBS5 gene did not have polydactyly. The contribution of BBS5 mutations to all cases of BBS has been estimated at 2% (Li et al., 2004) and 0.40% (Zaghloul and Katsanis, 2009). For a general phenotypic description and a discussion of genetic heterogeneity of Bardet-Biedl syndrome, see BBS1 (209900).

Microcephaly and chorioretinopathy-2 is an autosomal recessive developmental disorder characterized by delayed psychomotor development, visual impairment, and short stature (summary by Martin et al., 2014). For a discussion of genetic heterogeneity of microcephaly and chorioretinopathy, see MCCRP1 (251270).

Any cone-rod dystrophy in which the cause of the disease is a mutation in the DRAM2 gene.

Achromatopsia is characterized by reduced visual acuity, pendular nystagmus, increased sensitivity to light (photophobia), a small central scotoma, eccentric fixation, and reduced or complete loss of color discrimination. All individuals with achromatopsia (achromats) have impaired color discrimination along all three axes of color vision corresponding to the three cone classes: the protan or long-wavelength-sensitive cone axis (red), the deutan or middle-wavelength-sensitive cone axis (green), and the tritan or short-wavelength-sensitive cone axis (blue). Most individuals have complete achromatopsia, with total lack of function of all three types of cones. Rarely, individuals have incomplete achromatopsia, in which one or more cone types may be partially functioning. The manifestations are similar to those of individuals with complete achromatopsia, but generally less severe. Hyperopia is common in achromatopsia. Nystagmus develops during the first few weeks after birth followed by increased sensitivity to bright light. Best visual acuity varies with severity of the disease; it is 20/200 or less in complete achromatopsia and may be as high as 20/80 in incomplete achromatopsia. Visual acuity is usually stable over time; both nystagmus and sensitivity to bright light may improve slightly. Although the fundus is usually normal, macular changes (which may show early signs of progression) and vessel narrowing may be present in some affected individuals. Defects in the macula are visible on optical coherence tomography.

Any Senior-Loken syndrome in which the cause of the disease is a mutation in the WDR19 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.

Patterned macular dystrophy-3 (MDPT3), also called Martinique crinkled retinal pigment epitheliopathy, appears in the fourth or fifth decade of life and is characterized by a 'dry desert land' pattern of the fundus, involving the posterior pole initially and progressing from the temporal fovea to the periphery of the retina. Polypoid choroidal vasculopathy, choroidal neovascularization, or atrophic fibrous macular scarring can cause reduced visual acuity after age 50. Late-stage MDPT3 consists of a retinitis pigmentosa (RP; see 268000)-like phenotype due to death of retinal pigment epithelium (RPE) and photoreceptor cells. The dry desert land pattern observed on fundus examination corresponds to an irregular thickness of the Bruch membrane and the RPE, with a scalloped elevation ('crinkling') of the RPE observed on optical coherence tomography (OCT). Full-field electroretinography may be normal at preclinical and early stages of the dystrophy, but later cone and rod responses are severely reduced, consistent with progressive photoreceptor cell dysfunction and death at the final state (summary by Meunier et al., 2016). For a general phenotypic description and discussion of genetic heterogeneity of patterned macular dystrophy, see MDPT1 (169150).

Retinitis pigmentosa-82 with or without situs inversus (RP82) is an autosomal recessive form of retinal degeneration characterized by initial loss of rod photoreceptors, resulting in impaired night vision followed by progressive visual field constriction as both rod and cone photoreceptors die. Some affected individuals have situs inversus (Davidson et al., 2013; Audo et al., 2017). Male patients with infertility due to reduced or absent sperm motility have been reported; female fertility appears to be unaffected (Moye et al., 2019).

Hypotaurinemic retinal degeneration and cardiomyopathy (HTRDC) is an autosomal recessive disorder characterized by low plasma taurine, childhood-onset progressive retinal degeneration, and cardiomyopathy (Ansar et al., 2020).

SHILCA is characterized by early-onset retinal degeneration in association with sensorineural hearing loss, short stature, vertebral anomalies, and epiphyseal dysplasia, as well as motor and intellectual delay. Delayed myelination, leukoencephalopathy, and hypoplasia of the corpus callosum and cerebellum have been observed on brain MRI (Bedoni et al., 2020).

Infantile-onset multisystem neurologic, endocrine, and pancreatic disease-2 (IMNEPD2) is an autosomal recessive multisystemic disorder characterized by cholestatic hepatitis, poor feeding associated with poor overall growth, and hypoglycemia apparent from infancy. Most, but not all, patients have variable global developmental delay. Additional common features include sensorineural deafness, retinal abnormalities with visual defects, and hypotonia. Some patients have endocrine abnormalities, including hyperinsulinemic hypoglycemia, pancreatic dysfunction, hypothyroidism, and primary amenorrhea. Additional features may include hypertriglyceridemia, anemia, proteinuria, increased lactate, and recurrent infections. Brain imaging often shows dysmyelination, thin corpus callosum, cerebral atrophy, and white matter abnormalities. Although the clinical manifestations and severity of the disorder are highly variable, death in early childhood may occur (summary by Williams et al., 2019 and Zeiad et al., 2021). For a discussion of genetic heterogeneity of IMNEPD, see IMNEPD1 (616263).

Cone-rod dystrophy-24 (CORD24) is characterized by night blindness, defective color vision, and reduced visual acuity. Macular atrophy, macular pigmentation deposits, and drusen-like deposits in the macula have been observed. Age at onset varies widely, from the first to the sixth decades of live (Kobayashi et al., 2000; Huang et al., 2013; Zenteno et al., 2023). For a general phenotypic description and discussion of genetic heterogeneity of CORD, see CORD2 (120970).