Primary ciliary dyskinesia (PCD; CILD) is an autosomal recessive disorder resulting from loss of normal ciliary function. Kartagener (pronounced KART-agayner) syndrome is characterized by the combination of primary ciliary dyskinesia and situs inversus, and occurs in approximately half of patients with ciliary dyskinesia. Since normal nodal ciliary movement in the embryo is required for normal visceral asymmetry, absence of normal ciliary movement results in a lack of definitive patterning; thus, random chance alone appears to determine whether the viscera take up the normal or reversed left-right position during embryogenesis. This explains why approximately 50% of patients, even within the same family, have situs inversus (summary by Afzelius, 1976; El Zein et al., 2003). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia and the Kartagener syndrome, see CILD1 (244400).

Primary ciliary dyskinesia is a disorder characterized by chronic respiratory tract infections, abnormally positioned internal organs, and the inability to have children (infertility). The signs and symptoms of this condition are caused by abnormal cilia and flagella. Cilia are microscopic, finger-like projections that stick out from the surface of cells. They are found in the linings of the airway, the reproductive system, and other organs and tissues. Flagella are tail-like structures, similar to cilia, that propel sperm cells forward.\n\nIn the respiratory tract, cilia move back and forth in a coordinated way to move mucus towards the throat. This movement of mucus helps to eliminate fluid, bacteria, and particles from the lungs. Most babies with primary ciliary dyskinesia experience breathing problems at birth, which suggests that cilia play an important role in clearing fetal fluid from the lungs. Beginning in early childhood, affected individuals develop frequent respiratory tract infections. Without properly functioning cilia in the airway, bacteria remain in the respiratory tract and cause infection. People with primary ciliary dyskinesia also have year-round nasal congestion and a chronic cough. Chronic respiratory tract infections can result in a condition called bronchiectasis, which damages the passages, called bronchi, leading from the windpipe to the lungs and can cause life-threatening breathing problems.\n\nApproximately 12 percent of people with primary ciliary dyskinesia have a condition known as heterotaxy syndrome or situs ambiguus, which is characterized by abnormalities of the heart, liver, intestines, or spleen. These organs may be structurally abnormal or improperly positioned. In addition, affected individuals may lack a spleen (asplenia) or have multiple spleens (polysplenia). Heterotaxy syndrome results from problems establishing the left and right sides of the body during embryonic development. The severity of heterotaxy varies widely among affected individuals.\n\nSome individuals with primary ciliary dyskinesia have abnormally placed organs within their chest and abdomen. These abnormalities arise early in embryonic development when the differences between the left and right sides of the body are established. About 50 percent of people with primary ciliary dyskinesia have a mirror-image reversal of their internal organs (situs inversus totalis). For example, in these individuals the heart is on the right side of the body instead of on the left. Situs inversus totalis does not cause any apparent health problems. When someone with primary ciliary dyskinesia has situs inversus totalis, they are often said to have Kartagener syndrome.\n\nPrimary ciliary dyskinesia can also lead to infertility. Vigorous movements of the flagella are necessary to propel the sperm cells forward to the female egg cell. Because their sperm do not move properly, males with primary ciliary dyskinesia are usually unable to father children. Infertility occurs in some affected females and is likely due to abnormal cilia in the fallopian tubes.\n\nAnother feature of primary ciliary dyskinesia is recurrent ear infections (otitis media), especially in young children. Otitis media can lead to permanent hearing loss if untreated. The ear infections are likely related to abnormal cilia within the inner ear.\n\nRarely, individuals with primary ciliary dyskinesia have an accumulation of fluid in the brain (hydrocephalus), likely due to abnormal cilia in the brain.

Rarely, individuals with primary ciliary dyskinesia have an accumulation of fluid in the brain (hydrocephalus), likely due to abnormal cilia in the brain.\n\nAnother feature of primary ciliary dyskinesia is recurrent ear infections (otitis media), especially in young children. Otitis media can lead to permanent hearing loss if untreated. The ear infections are likely related to abnormal cilia within the inner ear.\n\nPrimary ciliary dyskinesia can also lead to infertility. Vigorous movements of the flagella are necessary to propel the sperm cells forward to the female egg cell. Because their sperm do not move properly, males with primary ciliary dyskinesia are usually unable to father children. Infertility occurs in some affected females and is likely due to abnormal cilia in the fallopian tubes.\n\nSome individuals with primary ciliary dyskinesia have abnormally placed organs within their chest and abdomen. These abnormalities arise early in embryonic development when the differences between the left and right sides of the body are established. About 50 percent of people with primary ciliary dyskinesia have a mirror-image reversal of their internal organs (situs inversus totalis). For example, in these individuals the heart is on the right side of the body instead of on the left. Situs inversus totalis does not cause any apparent health problems. When someone with primary ciliary dyskinesia has situs inversus totalis, they are often said to have Kartagener syndrome.\n\nApproximately 12 percent of people with primary ciliary dyskinesia have a condition known as heterotaxy syndrome or situs ambiguus, which is characterized by abnormalities of the heart, liver, intestines, or spleen. These organs may be structurally abnormal or improperly positioned. In addition, affected individuals may lack a spleen (asplenia) or have multiple spleens (polysplenia). Heterotaxy syndrome results from problems establishing the left and right sides of the body during embryonic development. The severity of heterotaxy varies widely among affected individuals.\n\nIn the respiratory tract, cilia move back and forth in a coordinated way to move mucus towards the throat. This movement of mucus helps to eliminate fluid, bacteria, and particles from the lungs. Most babies with primary ciliary dyskinesia experience breathing problems at birth, which suggests that cilia play an important role in clearing fetal fluid from the lungs. Beginning in early childhood, affected individuals develop frequent respiratory tract infections. Without properly functioning cilia in the airway, bacteria remain in the respiratory tract and cause infection. People with primary ciliary dyskinesia also have year-round nasal congestion and a chronic cough. Chronic respiratory tract infections can result in a condition called bronchiectasis, which damages the passages, called bronchi, leading from the windpipe to the lungs and can cause life-threatening breathing problems.\n\nPrimary ciliary dyskinesia is a disorder characterized by chronic respiratory tract infections, abnormally positioned internal organs, and the inability to have children (infertility). The signs and symptoms of this condition are caused by abnormal cilia and flagella. Cilia are microscopic, finger-like projections that stick out from the surface of cells. They are found in the linings of the airway, the reproductive system, and other organs and tissues. Flagella are tail-like structures, similar to cilia, that propel sperm cells forward.

Primary ciliary dyskinesia is an autosomal recessive disorder resulting from loss of normal ciliary function. Kartagener (pronounced KART-agayner) syndrome is characterized by the combination of primary ciliary dyskinesia and situs inversus, and occurs in approximately half of patients with ciliary dyskinesia. Since normal nodal ciliary movement in the embryo is required for normal visceral asymmetry, absence of normal ciliary movement results in a lack of definitive patterning; thus, random chance alone appears to determine whether the viscera take up the normal or reversed left-right position during embryogenesis. This explains why approximately 50% of patients, even within the same family, have situs inversus (Afzelius, 1976; El Zein et al., 2003). For a general description and a discussion of genetic heterogeneity of primary ciliary dyskinesia and Kartagener syndrome, see CILD1 (244400).

Primary ciliary dyskinesia is an autosomal recessive disorder resulting from loss of normal ciliary function. Kartagener (pronounced KART-agayner) syndrome is characterized by the combination of primary ciliary dyskinesia and situs inversus, and occurs in approximately half of patients with ciliary dyskinesia. Since normal nodal ciliary movement in the embryo is required for normal visceral asymmetry, absence of normal ciliary movement results in a lack of definitive patterning; thus, random chance alone appears to determine whether the viscera take up the normal or reversed left-right position during embryogenesis. This explains why approximately 50% of patients, even within the same family, have situs inversus (Afzelius, 1976; El Zein et al., 2003). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia and the Kartagener syndrome, see CILD1 (244400).

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.

Primary ciliary dyskinesia-18 is an autosomal recessive disorder characterized by early infantile onset of recurrent sinopulmonary infections due to ciliary dysfunction and impaired airway clearance. Males are infertile and about half of patients have situs inversus. Electron microscopy of cilia shows a defect of the outer and inner dynein arms and impaired ciliary function (summary by Horani et al., 2012).

Primary ciliary dyskinesia-21 (CILD21) is an autosomal recessive ciliopathy characterized by infantile onset of chronic sinopulmonary infections resulting from abnormal ciliary function. Electron microscopy of respiratory epithelial cells shows normal outer and inner dynein arms, but absence of nexin links and defects in the nexin-dynein regulatory complex (N-DRC). Video microscopy of patient cilia shows an increased beat frequency with decreased bending amplitude (summary by Wirschell et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-22 (CILD22) is an autosomal recessive disorder caused by defective structure and function of cilia or flagella. Ciliary dysfunction causes respiratory distress in term neonates, impaired mucociliary clearance, chronic cough, sinusitis, bronchiectasis, and male infertility. Defective motility of embryonic nodal cilia leads to situs abnormalities in about 50% of patients. CILD22 is characterized by defects of the inner and outer dynein arms (summary by Zariwala et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-24 is an autosomal recessive disorder resulting from defects of motile cilia. It is characterized clinically by sinopulmonary infection and subfertility; situs inversus is not observed. Ultrastructural examination of mutant cilia shows defects of the central microtubule complex and radial spokes (summary by Kott et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Primary ciliary dyskinesia-26 is an autosomal recessive disorder caused by defective ciliary movement. Affected individuals have neonatal respiratory distress, recurrent upper and lower airway disease, and bronchiectasis. About half of patients show laterality defects, including situs inversus totalis. Respiratory cilia from patients show defects in the inner and outer dynein arms (summary by Austin-Tse et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Primary ciliary dyskinesia-27 is an autosomal recessive disorder caused by defective ciliary movement. Affected individuals have neonatal respiratory distress, recurrent upper and lower airway disease, and bronchiectasis. Respiratory cilia from patients show defects in the inner dynein arms and nexin links. Situs inversus has not been reported in these patients (summary by Austin-Tse et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Primary ciliary dyskinesia-28 (CILD28) is an autosomal recessive disorder caused by defective ciliary movement. Affected individuals have recurrent upper and lower airway disease, bronchiectasis, and decreased fertility. About half of patients show laterality defects, including situs inversus. Respiratory cilia from patients show defects in both the inner and outer dynein arms (summary by Knowles et al., 2013). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-29 is an autosomal recessive disorder characterized by early childhood onset of recurrent respiratory infections due to defective mucociliary clearance. Patients do not have situs inversus (summary by Wallmeier et al., 2014). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Any primary ciliary dyskinesia in which the cause of the disease is a mutation in the CCDC151 gene.

Primary ciliary dyskinesia-32 is an autosomal recessive disorder caused by defective structure and function of cilia. Ciliary dysfunction causes respiratory distress in term neonates, impaired mucociliary clearance, chronic respiratory infections, bronchiectasis, and infertility. The ciliary defect affects the central pair complex and radial spokes of the 9+2 motile cilia; affected individuals do not have situs abnormalities (summary by Jeanson et al., 2015). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-35 (CILD35) is an autosomal recessive disorder characterized by recurrent upper and lower respiratory infections due to defective ciliary function. Examination of respiratory cilia shows lack of outer dynein arms (ODAs) and immotile cilia. Some patients may have laterality defects (summary by Wallmeier et al., 2016). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-34 (CILD34) is an autosomal recessive disorder characterized by childhood onset of recurrent sinopulmonary infections due to impaired ciliary function. Affected males are infertile due to impaired sperm function and viability. Laterality defects have not been observed in this type of CILD (summary by El Khouri et al., 2016). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

CILD36 is an X-linked recessive disorder characterized by chronic airway disease and recurrent sinopulmonary infections beginning in childhood and caused by defective ciliary function. Affected individuals also have infertility due to defective sperm flagella. About half of patients have laterality defects due to ciliary dysfunction at the embryonic node (summary by Paff et al., 2017). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

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).

Primary ciliary dyskinesia-38 is an autosomal recessive disorder characterized by chronic airway disease and recurrent sinopulmonary infections beginning in infancy and caused by defective ciliary function. Affected individuals often have neonatal respiratory distress and may later have infertility. About half of patients have laterality defects due to ciliary dysfunction in early embryonic development (summary by Fassad et al., 2018 and Hoben et al., 2018). For a general phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-39 (CILD39) is an autosomal recessive disorder characterized by chronic sinopulmonary infections beginning soon after birth and laterality defects in about 50% of patients. Although patient nasal ciliary samples have normal structure, detailed studies may show ciliary kinetic defects in some patients (summary by Bonnefoy et al., 2018). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see 244400.

Primary ciliary dyskinesia-40 (CILD40) is an autosomal recessive disorder with a relatively mild respiratory phenotype compared to other CILDs. Patients present in childhood with mild upper respiratory symptoms and infections, but typically do not develop serious lung disease. Nitric oxide levels are low-normal or normal. All reported patients have had situs inversus, including several with severe congenital cardiac malformations, but left-right body asymmetry is still theoretically random and would occur in 50% of patients (summary by Loges et al., 2018). For a discussion of genetic heterogeneity of primary ciliary dyskinesia and Kartagener syndrome, see CILD1 (244400).

Primary ciliary dyskinesia-42 (CILD42) is an autosomal recessive disorder characterized by a defect in motile cilia and ciliary clearance resulting in the onset of respiratory insufficiency soon after birth, and associated with recurrent upper and lower respiratory infections with chronic progressive lung disease. Other more variable features may include infertility and mild hydrocephalus. Patients with this form of the disorder do not have situs abnormalities. The disorder is considered to be a type of ciliopathy known as 'reduced generation of multiple motile cilia' (RGMC) (summary by Boon et al., 2014). For a discussion of genetic heterogeneity of primary ciliary dyskinesia, CILD1 (244400).

Primary ciliary dyskinesia-44 (CILD44) is an autosomal recessive disorder characterized by recurrent sinopulmonary infections resulting from defective mucociliary clearance. Affected individuals have onset of symptoms in infancy or early childhood, and the repetitive nature of the disorder results in bronchiectasis. Although respiratory epithelial cell motile cilia are shorter than normal and overall ciliary motion is decreased, nasal nitric oxide, radial ciliary structure, and ciliary beat frequency are normal. In addition, patients do not have situs inversus (summary by Chivukula et al., 2020). For a phenotypic description and a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Visceral heterotaxy-11 (HTX11) is characterized by a failure to generate normal left-right visceral asymmetry during embryogenesis, which can result in heterotaxy syndrome or situs inversus totalis. Affected individuals may experience mild chronic respiratory symptoms, but do not fulfill the criteria for primary ciliary dyskinesia (see 244400). Male infertility associated with reduced flagellar motility has been reported (Dougherty et al., 2020). For a discussion of genetic heterogeneity of visceral heterotaxy, see HTX1 (306955).

Visceral heterotaxy-10 (HTX10) is characterized by a failure to generate normal left-right visceral asymmetry during embryogenesis, which can result in heterotaxy syndrome or situs inversus totalis. Affected individuals may experience mild chronic respiratory symptoms, but do not fulfill the criteria for primary ciliary dyskinesia (see 244400). Male infertility has been reported (Ta-Shma et al., 2015; Dougherty et al., 2020). For a discussion of genetic heterogeneity of visceral heterotaxy, see HTX1 (306955).

Primary ciliary dyskinesia-49 (CILD49) without situs inversus is an autosomal recessive disorder characterized by the onset of recurrent respiratory infections, chronic cough, and bronchiectasis in early childhood due to defective ciliary clearance. Affected males also show infertility due to defective flagellar morphology and function. Nasal nitric oxide (NO) levels are normal and situs abnormalities are not observed (Sha et al., 2020; Biebach et al., 2022). For a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).

Primary ciliary dyskinesia-51 (CILD51) is characterized by male infertility due to multiple morphologic abnormalities of the sperm flagella (MMAF), resulting in severely reduced progressive motility. Some men also have a low sperm count. In addition, affected individuals experience chronic rhinosinusitis and bronchitis, and recurrent upper and lower respiratory infections, and some exhibit dextrocardia and/or situs inversus (Guo et al., 2021). For a discussion of genetic heterogeneity of primary ciliary dyskinesia, see CILD1 (244400).