Clinical and Genetic Analysis of Children with Kartagener Syndrome

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder characterized by dysfunction of motile cilia causing ineffective mucus clearance and organ laterality defects. In this study, two unrelated Portuguese children with strong PCD suspicion underwent extensive clinical and genetic assessments by whole-exome sequencing (WES), as well as ultrastructural analysis of cilia by transmission electron microscopy (TEM) to identify their genetic etiology. These analyses confirmed the diagnostic of Kartagener syndrome (KS) (PCD with situs inversus). Patient-1 showed a predominance of the absence of the inner dynein arms with two disease-causing variants in the CCDC40 gene. Patient-2 showed the absence of both dynein arms and WES disclosed two novel high impact variants in the DNAH5 gene and two missense variants in the DNAH7 gene, all possibly deleterious. Moreover, in Patient-2, functional data revealed a reduction of gene expression and protein mislocalization in both genes’ products. Our work calls the researcher’s attention to the complexity of the PCD and to the possibility of gene interactions modelling the PCD phenotype. Further, it is demonstrated that even for well-known PCD genes, novel pathogenic variants could have importance for a PCD/KS diagnosis, reinforcing the difficulty of providing genetic counselling and prenatal diagnosis to families.

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Biallelic Mutations in LRRC56 encoding a protein associated with intraflagellar transport, cause mucociliary clearance and laterality defects

10.1101/288852 ◽

2018 ◽

Cited By ~ 2

Author(s):

Serge Bonnefoy ◽

Christopher M. Watson ◽

Kristin D. Kernohan ◽

Moara Lemos ◽

Sebastian Hutchinson ◽

...

Keyword(s):

High Speed ◽

Respiratory Infections ◽

Fluid Flows ◽

Intraflagellar Transport ◽

Distal Portion ◽

Mucus Clearance ◽

Transmission Electron ◽

Dynein Arms ◽

Biallelic Mutations ◽

Laterality Defects

ABSTRACTDefective motile cilia are responsible for a group of heterogeneous genetic conditions characterised by dysfunction of the apparatus responsible for generating fluid flows. Primary ciliary dyskinesia (PCD) is the prototype for such disorders and presents with impaired pulmonary mucus clearance, susceptibility to chronic recurrent respiratory infections, male infertility and laterality defects in about 50 % of patients. Here we report biallelic variants in LRRC56 (also known as ODA8), identified in two unrelated consanguineous families. The phenotype comprises laterality defects and chronic pulmonary infections. High speed video microscopy of cultured patient epithelial cells showed severely dyskinetic cilia, but no obvious ultra-structural abnormalities on routine transmission electron microscopy (TEM). Further investigation revealed that LRRC56 interacts with the intraflagellar transport (IFT) protein IFT88. The link to IFT was interrogated in Trypanosoma brucei. In this protist, LRRC56 is recruited to the cilium during axoneme construction, where it co-localises with IFT trains and facilitates the addition of dynein arms to the distal end of the flagellum. In T. brucei carrying LRRC56 null mutations, or a mutation (p.Leu259Pro) corresponding to the p.Leu140Pro variant seen in one of the affected families, we observed abnormal ciliary beat patterns and an absence of outer dynein arms restricted to the distal portion of the axoneme. Together, our findings confirm that deleterious variants in LRRC56 result in a human disease, and suggest this protein has a likely role in dynein transport during cilia assembly that is evolutionarily important for cilia motility.

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Pathogenic variants identified by whole-exome sequencing in Chinese patients with primary ciliary dyskinesia

10.21203/rs.3.rs-403380/v1 ◽

2021 ◽

Author(s):

Ye Yutian ◽

Huang Qijun ◽

Chen Lipeng ◽

Liang Chunxian ◽

Yuan Fang ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Primary Ciliary Dyskinesia ◽

Genetic Factors ◽

Autosomal Recessive Disorder ◽

Chinese Patients ◽

Causative Gene ◽

Pathogenic Variants ◽

Whole Exome ◽

Ciliary Dyskinesia

Abstract Background: The genetic factors contributing to primary ciliary dyskinesia (PCD), a rare autosomal recessive disorder, remain elusive for approximately 20–35% of patients with complex and abnormal clinical phenotypes. Our study aimed to identify causative variants of PCD-associated pathogenic candidate genes using whole-exome sequencing (WES). Methods: All patients were diagnosed with PCD based on clinical phenotype or transmission electron microscopy (TEM) images of cilia. WES and bioinformatic analysis were then conducted for patients with PCD. Identified candidate variants were validated by Sanger sequencing. Pathogenicity of candidate variants was then evaluated using in silico software and the American College of Medical Genetics and Genomics (ACMG) database.Results: In total, 15 rare variants were identified in patients with PCD, among which were three homozygous causative variants (including one splicing variant) in the PCD-associated genes CCDC40 and DNAI1. Moreover, two stop-gain heterozygous variants of DNAAF3 and DNAH1 were classified as pathogenic variants by the ACMG criteria.Conclusions: This study identified novel potential pathogenic genetic factors associated with PCD. Noteworthy, the PCD patients carried multiple rare causative gene variants, thereby suggesting that known causative genes along with other functional genes should be considered for such heterogeneous genetic disorders.

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Emerging Genotype-Phenotype Relationships in Primary Ciliary Dyskinesia

International Journal of Molecular Sciences ◽

10.3390/ijms22158272 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8272

Author(s):

Steven K Brennan ◽

Thomas W Ferkol ◽

Stephanie D Davis

Keyword(s):

Primary Ciliary Dyskinesia ◽

Pulmonary Infections ◽

Disease Research ◽

The Past ◽

Clinical Presentations ◽

Organ Laterality ◽

Ciliary Dyskinesia ◽

Laterality Defects ◽

Severe Lung Disease ◽

Severe Lung

Primary ciliary dyskinesia (PCD) is a rare inherited condition affecting motile cilia and leading to organ laterality defects, recurrent sino-pulmonary infections, bronchiectasis, and severe lung disease. Research over the past twenty years has revealed variability in clinical presentations, ranging from mild to more severe phenotypes. Genotype and phenotype relationships have emerged. The increasing availability of genetic panels for PCD continue to redefine these genotype-phenotype relationships and reveal milder forms of disease that had previously gone unrecognized.

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Whole-exome sequencing accuracy in the diagnosis of primary ciliary dyskinesia

ERJ Open Research ◽

10.1183/23120541.00213-2020 ◽

2020 ◽

Vol 6 (4) ◽

pp. 00213-2020

Author(s):

Alex Gileles-Hillel ◽

Hagar Mor-Shaked ◽

David Shoseyov ◽

Joel Reiter ◽

Reuven Tsabari ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Primary Ciliary Dyskinesia ◽

Diagnostic Yield ◽

Characteristic Curve ◽

Transmission Electron Microscopy Analysis ◽

Alternative Diagnosis ◽

Pathogenic Variants ◽

Whole Exome ◽

Ciliary Dyskinesia

The diagnosis of primary ciliary dyskinesia (PCD) relies on clinical features and sophisticated studies. The detection of bi-allelic disease-causing variants confirms the diagnosis. However, a standardised genetic panel is not widely available and new disease-causing genes are continuously identified.To assess the accuracy of untargeted whole-exome sequencing (WES) as a diagnostic tool for PCD, patients with symptoms highly suggestive of PCD were consecutively included. Patients underwent measurement of nasal nitric oxide (nNO) levels, ciliary transmission electron microscopy analysis (TEM) and WES. A confirmed PCD diagnosis in symptomatic patients was defined as a recognised ciliary ultrastructural defect on TEM and/or two pathogenic variants in a known PCD-causing gene.Forty-eight patients (46% male) were enrolled, with a median age of 10.0 years (range 1.0–37 years). In 36 patients (75%) a diagnosis of PCD was confirmed, of which 14 (39%) patients had normal TEM. A standalone untargeted WES had a diagnostic yield of 94%, identifying bi-allelic variants in 11 known PCD-causing genes in 34 subjects. A nNO<77 nL·min was nonspecific when including patients younger than 5 years (area under the receiver operating characteristic curve (AUC) 0.75, 95% CI 0.60–0.90). Consecutive WES considerably improved the diagnostic accuracy of nNO in young children (AUC 0.97, 95% CI 0.93–1). Finally, WES established an alternative diagnosis in four patients.In patients with clinically suspected PCD and low nNO levels, WES is a simple, beneficial and accurate next step to confirm the diagnosis of PCD or suggest an alternative diagnosis, especially in preschool-aged children in whom nNO is less specific.

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Identification of two novel pathogenic variants of PIBF1 by whole exome sequencing in a 2-year-old boy with Joubert syndrome

BMC Medical Genetics ◽

10.1186/s12881-020-01130-x ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Yue Shen ◽

Hao Wang ◽

Zhimin Liu ◽

Minna Luo ◽

Siyu Ma ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Autosomal Recessive ◽

Autosomal Recessive Disorder ◽

Autosomal Recessive Inheritance ◽

Joubert Syndrome ◽

Causative Gene ◽

Pathogenic Variants ◽

Whole Exome ◽

Syndrome Individual

Abstract Background Joubert syndrome (OMIM 213300) is an autosomal recessive disorder with gene heterogeneity. Causal genes and their variants have been identified by sequencing or other technologies for Joubert syndrome subtypes. Case presentation A two-year-old boy was diagnosed with Joubert syndrome by global development delay and molar tooth sign of mid-brain. Whole exome sequencing was performed to detect the causative gene variants in this individual, and the candidate pathogenic variants were verified by Sanger sequencing. We identified two pathogenic variants (NM_006346.2: c.1147delC and c.1054A > G) of PIBF1 in this Joubert syndrome individual, which is consistent with the mode of autosomal recessive inheritance. Conclusion In this study, we identified two novel pathogenic variants in PIBF1 in a Joubert syndrome individual using whole exome sequencing, thereby expanding the PIBF1 pathogenic variant spectrum of Joubert syndrome.

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Pathogenic variants identified using whole-exome sequencing in Chinese patients with primary ciliary dyskinesia

10.21203/rs.3.rs-156279/v2 ◽

2021 ◽

Author(s):

Yutian Ye ◽

Qijun Huang ◽

Lipeng Chen ◽

Chunxian Liang ◽

Kaixue Zhuang ◽

...

Keyword(s):

Exome Sequencing ◽

Whole Exome Sequencing ◽

Primary Ciliary Dyskinesia ◽

Rare Variants ◽

Genetic Disorders ◽

Autosomal Recessive Disorder ◽

Bioinformatic Analysis ◽

Chinese Patients ◽

Whole Exome ◽

Ciliary Dyskinesia

Abstract Background Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder. The genetic factors contributing to PCD pathogenesis remain elusive for approximately 20–35% of patients with complex and abnormal clinical phenotypes. Our study aimed to identify causative variants of sporadic PCD genes using whole-exome sequencing (WES). Result All patients were diagnosed with PCD based on clinical phenotype or transmission electron microscopy (TEM) images of cilia. WES and bioinformatic analysis were then conducted for patients with PCD. Identified candidate variants were validated by Sanger sequencing. Pathogenicity of candidate variants was then evaluated using in silico software and the American College of Medical Genetics and Genomics (ACMG) database. In total, 15 rare variants were identified in five patients with PCD. Five new variants of CCDC40, DNAH1, DNAAF3, and DNAI1 were considered causative variants and included one splicing and three homozygous variants. Conclusion Our study demonstrated that patients with PCD carry rare causative variants of multiple genes. Our findings indicated that not only known causative genes but also other functional genes should be considered for heterogeneous genetic disorders.

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Ciliary Dyneins and Dynein Related Ciliopathies

Cells ◽

10.3390/cells10081885 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1885

Author(s):

Dinu Antony ◽

Han G. Brunner ◽

Miriam Schmidts

Keyword(s):

Intraflagellar Transport ◽

Cytoplasmic Dynein ◽

Vertebrate Development ◽

Kartagener Syndrome ◽

Dynein Motor ◽

Axonemal Dynein ◽

Ciliary Dyskinesia ◽

Laterality Defects ◽

Renal Phenotype ◽

Ciliary Localization

Although ubiquitously present, the relevance of cilia for vertebrate development and health has long been underrated. However, the aberration or dysfunction of ciliary structures or components results in a large heterogeneous group of disorders in mammals, termed ciliopathies. The majority of human ciliopathy cases are caused by malfunction of the ciliary dynein motor activity, powering retrograde intraflagellar transport (enabled by the cytoplasmic dynein-2 complex) or axonemal movement (axonemal dynein complexes). Despite a partially shared evolutionary developmental path and shared ciliary localization, the cytoplasmic dynein-2 and axonemal dynein functions are markedly different: while cytoplasmic dynein-2 complex dysfunction results in an ultra-rare syndromal skeleto-renal phenotype with a high lethality, axonemal dynein dysfunction is associated with a motile cilia dysfunction disorder, primary ciliary dyskinesia (PCD) or Kartagener syndrome, causing recurrent airway infection, degenerative lung disease, laterality defects, and infertility. In this review, we provide an overview of ciliary dynein complex compositions, their functions, clinical disease hallmarks of ciliary dynein disorders, presumed underlying pathomechanisms, and novel developments in the field.

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Homozygous truncating NEK10 mutation, associated with primary ciliary dyskinesia: a case report

BMC Pulmonary Medicine ◽

10.1186/s12890-020-1175-1 ◽

2020 ◽

Vol 20 (1) ◽

Cited By ~ 1

Author(s):

Fuad Al Mutairi ◽

Randa Alkhalaf ◽

Abdullah Alkhorayyef ◽

Fayhan Alroqi ◽

Alyafee Yusra ◽

...

Keyword(s):

Primary Ciliary Dyskinesia ◽

Autosomal Recessive ◽

Autosomal Recessive Disorder ◽

Molecular Testing ◽

Case Presentation ◽

Immotile Cilia ◽

Whole Exome ◽

Novel Variant ◽

Pathophysiological Aspect ◽

Ciliary Dyskinesia

Abstract Background Primary Ciliary Dyskinesia (PCD) is also known as immotile-cilia syndrome, an autosomal recessive disorder of ciliary function, leading to mucus retention in the respiratory system in childhood. Our knowledge in the pathophysiological aspect of this devastating disorder is increasing with the advancement of genetic and molecular testing. Case presentation Here in, we report two siblings with a classical clinical and radiological presentation of PCD. Using whole exome sequencing we identified a homozygous truncating variant (c.3402 T > A); p.(Tyr1134*) in the NEK10 gene. Western bolt analysis revealed a decrease in the expression of NEK10 protein in the patient cells. Conclusions NEK10 plays a central role in the post-mitotic process of cilia assembly, regulating ciliary length and functions during physiological and pathological status. This study highlights the challenges of identifying disease-causing variants for a highly heterogeneous disorder and reports on the identification of a novel variant in NEK10 which recently associated with PCD.

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Zebrafish Motile Cilia as a Model for Primary Ciliary Dyskinesia

International Journal of Molecular Sciences ◽

10.3390/ijms22168361 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8361

Author(s):

Andreia L. Pinto ◽

Margarida Rasteiro ◽

Catarina Bota ◽

Sara Pestana ◽

Pedro Sampaio ◽

...

Keyword(s):

Primary Ciliary Dyskinesia ◽

Primary Cilia ◽

Electron Tomography ◽

Model Organism ◽

Autosomal Recessive Disorder ◽

High Resolution Data ◽

Immotile Cilia ◽

Dynein Arms ◽

Motile Cilia ◽

Ciliary Dyskinesia

Zebrafish is a vertebrate teleost widely used in many areas of research. As embryos, they develop quickly and provide unique opportunities for research studies owing to their transparency for at least 48 h post fertilization. Zebrafish have many ciliated organs that include primary cilia as well as motile cilia. Using zebrafish as an animal model helps to better understand human diseases such as Primary Ciliary Dyskinesia (PCD), an autosomal recessive disorder that affects cilia motility, currently associated with more than 50 genes. The aim of this study was to validate zebrafish motile cilia, both in mono and multiciliated cells, as organelles for PCD research. For this purpose, we obtained systematic high-resolution data in both the olfactory pit (OP) and the left–right organizer (LRO), a superficial organ and a deep organ embedded in the tail of the embryo, respectively. For the analysis of their axonemal ciliary structure, we used conventional transmission electron microscopy (TEM) and electron tomography (ET). We characterised the wild-type OP cilia and showed, for the first time in zebrafish, the presence of motile cilia (9 + 2) in the periphery of the pit and the presence of immotile cilia (still 9 + 2), with absent outer dynein arms, in the centre of the pit. In addition, we reported that a central pair of microtubules in the LRO motile cilia is common in zebrafish, contrary to mouse embryos, but it is not observed in all LRO cilia from the same embryo. We further showed that the outer dynein arms of the microtubular doublet of both the OP and LRO cilia are structurally similar in dimensions to the human respiratory cilia at the resolution of TEM and ET. We conclude that zebrafish is a good model organism for PCD research but investigators need to be aware of the specific physical differences to correctly interpret their results.

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Kartagener Syndrome: A Rare Genetic Disorder

Journal of Nepal Medical Association ◽

10.31729/jnma.206 ◽

2009 ◽

Vol 48 (173) ◽

Cited By ~ 2

Author(s):

Kunjan Shakya

Keyword(s):

Situs Inversus ◽

Primary Ciliary Dyskinesia ◽

Autosomal Recessive ◽

Genetic Disorder ◽

Clinical Manifestations ◽

Autosomal Recessive Disorder ◽

Kartagener Syndrome ◽

Irreversible Damage ◽

History Of ◽

Ciliary Dyskinesia

Kartagener Syndrome is a rare autosomal recessive disorder consisting of triad of sinusitis, bronchiectasis and situs inversus with dextrocardia. It is the subset of disorder called primary ciliary dyskinesia in which the cilia have abnormal structure and/or function resulting in multisystem diseases of various severity. Clinical manifestations include lifelong, chronic upper and lower respiratory tract diseases secondary to ineffective mucociliary clearance. Early diagnosis and management of chest infections can prevent irreversible damage to lungs and prevent potential lifelong complications. This case report is on a patient who presented with long standing history of sinusitis, bronchiectasis and on examination situs inversus with dextrocardia.Key Words:bronchiectasis, dextrocardia, kartagener syndrome, primary ciliary dyskinesia, situs inversus

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