Congenital oculomotor apraxia, first reported by Cogan (1952), is characterized by (1) defective or absent horizontal voluntary eye movements, and (2) defective or absent horizontal ocular attraction movements. Oculomotor apraxia occurs in ataxia-telangiectasia (208900). Also see ataxia-oculomotor apraxia syndrome (208920; 606002). Oculomotor apraxia has been observed in the neuronopathic form of Gaucher disease (type III; 231000) (Erikson and Wahlberg, 1985; Gross-Tsur et al., 1989).

Senior-Loken syndrome is an autosomal recessive disorder with the main features of nephronophthisis (NPHP; see 256100) and Leber congenital amaurosis (LCA; see 204000). For a general phenotypic description and a discussion of genetic heterogeneity of Senior-Loken syndrome, see 266900.

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.

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.

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.

Senior-Loken syndrome-4 (SLSN4) is an autosomal recessive disorder characterized by the association of the cystic renal disorder nephronophthisis with early-onset retinitis pigmentosa (Polak et al., 1983; Schuermann et al., 2002; Otto et al., 2002). For a general phenotypic description and a discussion of genetic heterogeneity of Senior-Loken syndrome, see 266900.

Senior-Løken syndrome is a rare disorder characterized by the combination of two specific features: a kidney condition called nephronophthisis and an eye condition known as Leber congenital amaurosis.\n\nNephronophthisis causes fluid-filled cysts to develop in the kidneys beginning in childhood. These cysts impair kidney function, initially causing increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). Nephronophthisis leads to end-stage renal disease (ESRD) later in childhood or in adolescence. ESRD is a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively.\n\nLeber congenital amaurosis primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color. This condition causes vision problems, including an increased sensitivity to light (photophobia), involuntary movements of the eyes (nystagmus), and extreme farsightedness (hyperopia). Some people with Senior-Løken syndrome develop the signs of Leber congenital amaurosis within the first few years of life, while others do not develop vision problems until later in childhood.

Nephronophthisis-4 (NPHP4) is characterized by juvenile-onset renal failure, with end-stage renal disease sometimes occurring as early as the first decade of life. Oculomotor apraxia has also been observed in some affected individuals (Mollet et al., 2002; Otto et al., 2002). For a general phenotypic description and a discussion of genetic heterogeneity of nephronophthisis, see NPHP1 (256100).

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).

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.

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.

Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease that leads to renal failure in childhood or adolescence. It is the most frequent genetic cause of renal failure in children. NPHP may be combined with extrarenal manifestations, such as liver fibrosis, situs inversus, or cardiac malformations. When nephronophthisis is combined with retinitis pigmentosa, the disorder is known as Senior-Loken syndrome (SLSN1; 266900); when it is combined with cerebellar vermis hypoplasia, the disorder is known as Joubert syndrome (JBTS1; 213300); and when it is combined with multiple developmental and neurologic abnormalities, the disorder is often known as Meckel-Gruber syndrome (MKS1; 249000). Because most NPHP gene products localize to the cilium or its associated structures, nephronophthisis and the related syndromes have been termed 'ciliopathies' (summary by Hoff et al., 2013). Clinical features of familial juvenile nephronophthisis include anemia, polyuria, polydipsia, isosthenuria, and death in uremia. Simms et al. (2009) provided a detailed review of nephronophthisis, including a discussion of clinical features and molecular genetics. Stokman et al. (2021) provided a review of NPHP, including clinical features, pathophysiology, and therapeutic approaches. Genetic Heterogeneity of Nephronophthisis NPHP2 (602088) is caused by mutation in the INVS gene (243305) on chromosome 9q31; NPHP3 (604387) is caused by mutation in the NPHP3 gene (608002) on chromosome 3q22; NPHP4 (606966) is caused by mutation in the NPHP4 gene (607215) on chromosome 1p36; NPHP7 (611498) is caused by mutation in the GLIS2 gene (608539) on chromosome 16p13; NPHP9 (613824) is caused by mutation in the NEK8 gene (609799) on chromosome 17q11; NPHP11 (613550) is caused by mutation in the TMEM67 gene (609884) on chromosome 8q22; NPHP12 (613820) is caused by mutation in the TTC21B gene (612014) on chromosome 2q24; NPHP13 (614377) is caused by mutation in the WDR19 gene (608151) on chromosome 4p14; NPHP14 (614844) is caused by mutation in the ZNF423 gene (604557) on chromosome 16; NPHP15 (614845) is caused by mutation in the CEP164 gene (614848) on chromosome 11q; NPHP16 (615382) is caused by mutation in the ANKS6 gene (615370) on chromosome 9q22; NPHP18 (615862) is caused by mutation in the CEP83 gene (615847) on chromosome 12q22; NPHP19 (616217) is caused by mutation in the DCDC2 gene (605755) on chromosome 6p22; and NPHP20 (617271) is caused by mutation in the MAPKBP1 gene (616786) on chromosome 15q13. Two disorders have been phenotypically described as 'NPHP-like' due to variable unique features: NPHPL1 (613159), caused by mutation in the XPNPEP3 gene (613553) on chromosome 22q13, and NPHPL2 (619468), caused by mutation in the SLC41A1 gene (610801) on chromosome 1q32.

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.

Nephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.\n\nAbout 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).\n\nNephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).\n\nNephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.

RHYNS syndrome is characterized by gaze palsy, retinitis pigmentosa, sensorineural hearing loss, hypopituitarism, nephronophthisis, and mild skeletal dysplasia (Di Rocco et al., 1997).

Nephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.\n\nNephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).\n\nAbout 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).\n\nNephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.

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.

Nephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.\n\nAbout 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).\n\nNephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).\n\nNephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.

Nephronophthisis-like nephropathy-1 (NPHPL1) is an autosomal recessive cystic kidney disease characterized by the onset of progressive renal insufficiency in childhood. End-stage renal disease occurs in the first 3 decades of life. The disorder may be associated with extrarenal manifestations, including hepatic and central nervous system involvement (summary by O'Toole et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of nephronophthisis, see NPHP1 (256100).

Nephronophthisis-11 (NPHP11) is an autosomal recessive kidney disease characterized histologically by renal interstitial infiltration with fibrosis, tubular atrophy with basement membrane disruption, and cyst development at the corticomedullary border. Hepatic fibrosis is also present. The clinical presentation includes polyuria, polydipsia, anemia, and growth retardation. End-stage renal disease develops in the first or second decade of life (Otto et al., 2009). For a general phenotypic description and a discussion of genetic heterogeneity of NPHP, see NPHP1 (256100).

Senior-Løken syndrome is a rare disorder characterized by the combination of two specific features: a kidney condition called nephronophthisis and an eye condition known as Leber congenital amaurosis.\n\nNephronophthisis causes fluid-filled cysts to develop in the kidneys beginning in childhood. These cysts impair kidney function, initially causing increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). Nephronophthisis leads to end-stage renal disease (ESRD) later in childhood or in adolescence. ESRD is a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively.\n\nLeber congenital amaurosis primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color. This condition causes vision problems, including an increased sensitivity to light (photophobia), involuntary movements of the eyes (nystagmus), and extreme farsightedness (hyperopia). Some people with Senior-Løken syndrome develop the signs of Leber congenital amaurosis within the first few years of life, while others do not develop vision problems until later in childhood.

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.

Nephronophthisis (NPHP) is an autosomal recessive kidney disease that leads to kidney cyst formation and progressive renal failure. NPHP is the most frequent genetic cause of end-stage renal failure in the first 3 decades of life (summary by Otto et al., 2008). For a general description and a discussion of genetic heterogeneity of NPHP, see NPHP1 (256100).

Cranioectodermal dysplasia (CED) is a ciliopathy with skeletal involvement (narrow thorax, shortened proximal limbs, syndactyly, polydactyly, brachydactyly), ectodermal features (widely spaced hypoplastic teeth, hypodontia, sparse hair, skin laxity, abnormal nails), joint laxity, growth deficiency, and characteristic facial features (frontal bossing, low-set simple ears, high forehead, telecanthus, epicanthal folds, full cheeks, everted lower lip). Most affected children develop nephronophthisis that often leads to end-stage kidney disease in infancy or childhood, a major cause of morbidity and mortality. Hepatic fibrosis and retinal dystrophy are also observed. Dolichocephaly, often secondary to sagittal craniosynostosis, is a primary manifestation that distinguishes CED from most other ciliopathies. Brain malformations and developmental delay may also occur.

A nephronophthisis that has material basis in homozygous or compound heterozygous mutation in the WDR19 gene on chromosome 4p14.

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.

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.

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.

Nephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.\n\nNephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).\n\nAbout 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).\n\nNephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.

Karyomegalic tubulointerstitial nephritis (KMIN) is a rare kidney disease characterized clinically by onset in the third decade of progressive renal failure. Renal biopsy shows chronic tubulointerstitial nephritis and interstitial fibrosis associated with enlarged and atypical tubular epithelial cell nuclei (summary by Baba et al., 2006).

Nephronophthisis can occur as part of separate syndromes that affect other areas of the body; these are often referred to as nephronophthisis-associated ciliopathies. For example, Senior-Løken syndrome is characterized by the combination of nephronophthisis and a breakdown of the light-sensitive tissue at the back of the eye (retinal degeneration); Joubert syndrome affects many parts of the body, causing neurological problems and other features, which can include nephronophthisis.\n\nAbout 85 percent of all cases of nephronophthisis are isolated, which means they occur without other signs and symptoms. Some people with nephronophthisis have additional features, which can include liver fibrosis, heart abnormalities, or mirror image reversal of the position of one or more organs inside the body (situs inversus).\n\nNephronophthisis eventually leads to end-stage renal disease (ESRD), a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively. Nephronophthisis can be classified by the approximate age at which ESRD begins: around age 1 (infantile), around age 13 (juvenile), and around age 19 (adolescent).\n\nNephronophthisis is a disorder that affects the kidneys. It is characterized by inflammation and scarring (fibrosis) that impairs kidney function. These abnormalities lead to increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). In addition, affected individuals develop fluid-filled cysts in the kidneys, usually in an area known as the corticomedullary region. Another feature of nephronophthisis is a shortage of red blood cells, a condition known as anemia.

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).

Nephronophthisis-18 is an autosomal recessive disorder characterized by chronic tubulointerstitial nephritis resulting in end-stage renal disease in early childhood. Extrarenal manifestations, including intellectual disability or liver changes, may occur in some patients (summary by Failler et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of nephronophthisis, see NPHP1 (256100).

Any nephronophthisis in which the cause of the disease is a mutation in the DCDC2 gene.

Senior-Loken syndrome-9 is an autosomal recessive disorder characterized by early-onset nephronophthisis and pigmentary retinopathy. Additional more variable features can include liver defects, skeletal anomalies, and obesity (summary by Bizet et al., 2015). For a phenotypic description and a discussion of genetic heterogeneity of Senior-Loken syndrome, see 266900.

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

Nephronophthisis-20 (NPHP20) is an autosomal recessive tubulointerstitial nephritis characterized by progressive renal fibrosis resulting in end-stage renal failure. The age at onset is relatively late compared to other forms of NPHP, and patients develop end-stage renal disease in the second or third decades. Unlike most other forms of NPHP, NPHP20 does not have features of a ciliopathy and patients do not appear to have extrarenal manifestations (summary by Macia et al., 2017). For a general phenotypic description and a discussion of genetic heterogeneity of nephronophthisis, see NPHP1 (256100).

Leber congenital amaurosis primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color. This condition causes vision problems, including an increased sensitivity to light (photophobia), involuntary movements of the eyes (nystagmus), and extreme farsightedness (hyperopia). Some people with Senior-Løken syndrome develop the signs of Leber congenital amaurosis within the first few years of life, while others do not develop vision problems until later in childhood.\n\nNephronophthisis causes fluid-filled cysts to develop in the kidneys beginning in childhood. These cysts impair kidney function, initially causing increased urine production (polyuria), excessive thirst (polydipsia), general weakness, and extreme tiredness (fatigue). Nephronophthisis leads to end-stage renal disease (ESRD) later in childhood or in adolescence. ESRD is a life-threatening failure of kidney function that occurs when the kidneys are no longer able to filter fluids and waste products from the body effectively.\n\nSenior-Løken syndrome is a rare disorder characterized by the combination of two specific features: a kidney condition called nephronophthisis and an eye condition known as Leber congenital amaurosis.

Any COACH syndrome in which the cause of the disease is a variation in the TMEM67 gene.

COACH syndrome is classically defined as Cerebellar vermis hypoplasia, Oligophrenia, Ataxia, Colobomas, and Hepatic fibrosis (Verloes and Lambotte, 1989). Brain MRI demonstrates the molar tooth sign, which is a feature of Joubert syndrome. The disorder has been described as a Joubert syndrome-related disorder with liver disease (summary by Doherty et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of COACH syndrome, see 216360.

Odontochondrodysplasia-1 (ODCD1) is characterized by mesomelic shortening of tubular bones, ligamentous laxity, and scoliosis, in association with dentinogenesis imperfecta involving both primary and secondary dentition. Affected individuals show variable severity. Radiologic features include trident pelvis, posteriorly flattened vertebrae, and brachydactyly with cone-shaped epiphyses (Maroteaux et al., 1996). Clinical variability and extraskeletal manifestations have been observed (Wehrle et al., 2019). Genetic Heterogeneity of Odontochondrodysplasia Odontochondrodysplasia-2 with hearing loss and diabetes (ODCD2; 619269) is caused by mutation in the TANGO1 gene (MIA3; 613455) on chromosome 1q41.

Polycystic kidney disease-8 (PKD8) is an autosomal dominant disorder characterized by enlarged kidneys, arterial hypertension, and kidney failure (Claus et al., 2023).