MedGen

Usher syndrome type I (USH1) is characterized by congenital, bilateral, profound sensorineural hearing loss, vestibular areflexia, and adolescent-onset retinitis pigmentosa (RP). Unless fitted with a cochlear implant, individuals do not typically develop speech. RP, a progressive, bilateral, symmetric degeneration of rod and cone functions of the retina, develops in adolescence, resulting in progressively constricted visual fields and impaired visual acuity. [from GeneReviews]

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). The hallmark of CLN3 is the ultrastructural pattern of lipopigment with a 'fingerprint' profile, which can have 3 different appearances: pure within a lysosomal residual body; in conjunction with curvilinear or rectilinear profiles; and as a small component within large membrane-bound lysosomal vacuoles. The combination of fingerprint profiles within lysosomal vacuoles is a regular feature of blood lymphocytes from patients with CLN3 (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730). [from OMIM]

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment pattern seen most often in CLN1 is referred to as granular osmiophilic deposits (GROD). The patterns most often observed in CLN2 and CLN3 are 'curvilinear' and 'fingerprint' profiles, respectively. CLN4, CLN5, CLN6, CLN7, and CLN8 show mixed combinations of granular, curvilinear, fingerprint, and rectilinear profiles. The clinical course includes progressive dementia, seizures, and progressive visual failure (Mole et al., 2005). Zeman and Dyken (1969) referred to these conditions as the 'neuronal ceroid lipofuscinoses.' Goebel (1995) provided a comprehensive review of the NCLs and noted that they are possibly the most common group of neurodegenerative diseases in children. Mole et al. (2005) provided a detailed clinical and genetic review of the neuronal ceroid lipofuscinoses. Genetic Heterogeneity of Neuronal Ceroid Lipofuscinosis See also CLN2 (204500), caused by mutation in the TPP1 gene (607998) on chromosome 11p15; CLN3 (204200), caused by mutation in the CLN3 gene (607042) on 16p12; CLN4 (162350), caused by mutation in the DNAJC5 gene (611203) on 20q13; CLN5 (256731), caused by mutation in the CLN5 gene (608102) on 13q22; CLN6A (601780) and CLN6B (204300), both caused by mutation in the CLN6 gene (606725) on 15q21; CLN7 (610951), caused by mutation in the MFSD8 gene (611124) on 4q28; CLN8 (600143) and the Northern epilepsy variant of CLN8 (610003), both caused by mutation in the CLN8 gene (607837) on 8p23; CLN10 (610127), caused by mutation in the CTSD gene (116840) on 11p15; CLN11 (614706), caused by mutation in the GRN gene (138945) on 17q21; CLN13 (615362), caused by mutation in the CTSF gene (603539) on 11q13; and CLN14 (611726), caused by mutation in the KCTD7 gene (611725) on 7q11. CLN9 (609055) has not been molecularly characterized. A disorder that was formerly designated neuronal ceroid lipofuscinosis-12 (CLN12) is now considered to be a variable form of Kufor-Rakeb syndrome (KRS; 606693). [from OMIM]

The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The clinical course includes progressive dementia, seizures, and progressive visual failure. The lipopigment pattern seen most often in CLN2 consists of 'curvilinear' profiles (Mole et al., 2005). For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730). [from OMIM]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the CRB1 gene. [from MONDO]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the EYS gene. [from MONDO]

Leber congenital amaurosis comprises a group of early-onset childhood retinal dystrophies characterized by vision loss, nystagmus, and severe retinal dysfunction. Patients usually present at birth with profound vision loss and pendular nystagmus. Electroretinogram (ERG) responses are usually nonrecordable. Other clinical findings may include high hypermetropia, photodysphoria, oculodigital sign, keratoconus, cataracts, and a variable appearance to the fundus (summary by Chung and Traboulsi, 2009). For a general description and a discussion of genetic heterogeneity of LCA, see 204000. [from OMIM]

Leber congenital amaurosis comprises a group of early-onset childhood retinal dystrophies characterized by vision loss, nystagmus, and severe retinal dysfunction. Patients usually present at birth with profound vision loss and pendular nystagmus. Electroretinogram (ERG) responses are usually nonrecordable. Other clinical findings may include high hypermetropia, photodysphoria, oculodigital sign, keratoconus, cataracts, and a variable appearance to the fundus (summary by Chung and Traboulsi, 2009). For a general description and a discussion of genetic heterogeneity of LCA, see 204000. [from OMIM]

Leber congenital amaurosis comprises a group of early-onset childhood retinal dystrophies characterized by vision loss, nystagmus, and severe retinal dysfunction. Patients usually present at birth with profound vision loss and pendular nystagmus. Electroretinogram (ERG) responses are usually nonrecordable. Other clinical findings may include high hypermetropia, photodysphoria, oculodigital sign, keratoconus, cataracts, and a variable appearance to the fundus (summary by Chung and Traboulsi, 2009). For a general description and a discussion of genetic heterogeneity of LCA, see 204000. [from OMIM]

Leber congenital amaurosis, also known as LCA, is an eye disorder that is present from birth (congenital). This condition primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color. People with this disorder typically have severe visual impairment beginning at birth or shortly afterward. The visual impairment tends to be severe and may worsen over time.

Leber congenital amaurosis is also associated with other vision problems, including an increased sensitivity to light (photophobia), involuntary movements of the eyes (nystagmus), and extreme farsightedness (hyperopia). The pupils, which usually expand and contract in response to the amount of light entering the eye, do not react normally to light. Instead, they expand and contract more slowly than normal, or they may not respond to light at all.

A specific behavior called Franceschetti's oculo-digital sign is characteristic of Leber congenital amaurosis. This sign consists of affected individuals poking, pressing, and rubbing their eyes with a knuckle or finger. Poking their eyes often results in the sensation of flashes of light called phosphenes. Researchers suspect that this behavior may contribute to deep-set eyes in affected children.

In very rare cases, delayed development and intellectual disability have been reported in people with the features of Leber congenital amaurosis. Because of the visual loss, affected children may become isolated. Providing children with opportunities to play, hear, touch, understand and other early educational interventions may prevent developmental delays in children with Leber congenital amaurosis.

At least 20 genetic types of Leber congenital amaurosis have been described. The types are distinguished by their genetic cause, patterns of vision loss, and related eye abnormalities. [from MedlinePlus Genetics]

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, whereas the less aggressive forms are usually considered juvenile retinitis pigmentosa (Gu et al., 1997). For a general phenotypic description and a discussion of genetic heterogeneity of Leber congenital amaurosis, see LCA1 (204000); for retinitis pigmentosa, see 268000. [from OMIM]

D-bifunctional protein deficiency is a disorder of peroxisomal fatty acid beta-oxidation. See also peroxisomal acyl-CoA oxidase deficiency (264470), caused by mutation in the ACOX1 gene (609751) on chromosome 17q25. The clinical manifestations of these 2 deficiencies are similar to those of disorders of peroxisomal assembly, including X-linked adrenoleukodystrophy (ALD; 300100), Zellweger cerebrohepatorenal syndrome (see 214100) and neonatal adrenoleukodystrophy (NALD; see 601539) (Watkins et al., 1995). DBP deficiency has been classified into 3 subtypes depending upon the deficient enzyme activity. Type I is a deficiency of both 2-enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase; type II is a deficiency of hydratase activity alone; and type III is a deficiency of dehydrogenase activity alone. Virtually all patients with types I, II, and III have a severe phenotype characterized by infantile-onset of hypotonia, seizures, and abnormal facial features, and most die before age 2 years. McMillan et al. (2012) proposed a type IV deficiency on the basis of less severe features; these patients have a phenotype reminiscent of Perrault syndrome (PRLTS1; 233400). Pierce et al. (2010) noted that Perrault syndrome and DBP deficiency overlap clinically and suggested that DBP deficiency may be underdiagnosed. [from OMIM]

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). [from OMIM]

Short-rib thoracic dysplasia (SRTD) with or without polydactyly refers to a group of autosomal recessive skeletal ciliopathies that are characterized by a constricted thoracic cage, short ribs, shortened tubular bones, and a 'trident' appearance of the acetabular roof. SRTD encompasses Ellis-van Creveld syndrome (EVC) and the disorders previously designated as Jeune syndrome or asphyxiating thoracic dystrophy (ATD), short rib-polydactyly syndrome (SRPS), and Mainzer-Saldino syndrome (MZSDS). Polydactyly is variably present, and there is phenotypic overlap in the various forms of SRTDs, which differ by visceral malformation and metaphyseal appearance. Nonskeletal involvement can include cleft lip/palate as well as anomalies of major organs such as the brain, eye, heart, kidneys, liver, pancreas, intestines, and genitalia. Some forms of SRTD are lethal in the neonatal period due to respiratory insufficiency secondary to a severely restricted thoracic cage, whereas others are compatible with life (summary by Huber and Cormier-Daire, 2012 and Schmidts et al., 2013). There is phenotypic overlap with the cranioectodermal dysplasias (Sensenbrenner syndrome; see CED1, 218330). For a discussion of genetic heterogeneity of short-rib thoracic dysplasia, see SRTD1 (208500). [from OMIM]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the TULP1 gene. [from MONDO]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the NRL gene. [from MONDO]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the PROM1 gene. [from MONDO]

An autosomal recessive retinopathy in which patients have increased sensitivity to blue light; perception of blue light is mediated by what is normally the least populous cone photoreceptor subtype, the S (short wavelength, blue) cones. Characteristics include visual loss, with night blindness occurring from early in life, varying degrees of L (long, red)- and M (middle, green)-cone vision, and retinal degeneration. [from MONDO]

Any retinitis pigmentosa in which the cause of the disease is a mutation in the PRCD gene. [from MONDO]

Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen. [from GeneReviews]