Mutations in Outer Dynein Arm Heavy Chain DNAH9 Cause Motile Cilia Defects and Situs Inversus

Clinical and molecular characteristics of 26 fetuses with lethal multiple congenital contractures

Multiple congenital contractures (MCC) due to fetal akinesia manifest across a broad spectrum of diseases, ranging from mild distal arthrogryposis to lethal fetal akinesia deformation sequence. We hereby present a series of 26 fetuses displaying severe MCC phenotypes from 18 families and describe detailed prenatal ultrasound findings, postmortem clinical evaluations, and genetic investigations. Most common prenatal findings were abnormal facial profile (65%), central nervous system abnormalities (62%), polyhydramnios (50%), increased nuchal translucency (50%), and fetal hydrops (35%). Postmortem examinations unveiled additional anomalies including facial dysmorphisms, dysplastic skeletal changes, ichthyosis, multiple pterygia, and myopathy, allowing preliminary diagnosis of particular Mendelian disorders in multiple patients. Evaluation of the parents revealed maternal grip myotonia in one family. By exome sequencing and targeted testing, we identified causative variants in ACTC1, CHST14, COG6, DMPK, DOK7, HSPG2, KLHL7, KLHL40, KIAA1109, NEB, PSAT1, RAPSN, USP14, and WASHC5 in 15 families, and one patient with a plausible diagnosis associated with biallelic NEB variants. Three patients received a dual diagnosis. Pathogenic alterations in newly discovered genes or in previously known genes recently linked to new MCC phenotypes were observed in 44% of the cohort. Our results provide new insights into the clinical and molecular landscape of lethal MCC phenotypes.

Practical guide for the diagnosis and management of primary ciliary dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a relatively rare genetic disorder that affects approximately 1 in 20,000 people. Approximately 50 genes are currently known to cause PCD. In light of differences in causative genes and the medical system in Japan compared with other countries, a practical guide was needed for the diagnosis and management of Japanese PCD patients.

METHODS

An ad hoc academic committee was organized under the Japanese Rhinologic Society to produce a practical guide, with participation by committee members from several academic societies in Japan. The practical guide including diagnostic criteria for PCD was approved by the Japanese Rhinologic Society, Japanese Society of Otolaryngology-Head and Neck Surgery, Japanese Respiratory Society, and Japanese Society of Pediatric Pulmonology.

RESULTS

The diagnostic criteria for PCD consist of six clinical features, six laboratory findings, differential diagnosis, and genetic testing. The diagnosis of PCD is categorized as definite, probable, or possible PCD based on a combination of the four items above. Diagnosis of definite PCD requires exclusion of cystic fibrosis and primary immunodeficiency, at least one of the six clinical features, and a positive result for at least one of the following: (1) Class 1 defect on electron microscopy of cilia, (2) pathogenic or likely pathogenic variants in a PCD-related gene, or (3) impairment of ciliary motility that can be repaired by correcting the causative gene variants in iPS cells established from the patient's peripheral blood cells.

CONCLUSION

This practical guide provides clinicians with useful information for the diagnosis and management of PCD in Japan.

A novel homozygous RSPH4A variant in a family with primary ciliary dyskinesia and literature review

Introduction: Primary ciliary dyskinesia (PCD) is a rare heterogeneous disease caused by abnormalities in motile cilia. In this case report, we first analyzed the clinical and genetic data of a proband who was suspected of having PCD on the basis of her clinical and radiological findings. Methods: Whole-exome sequencing was performed, and a variant in the RSPH4A gene was identified in the proband. Sanger sequencing was used for validation of RSPH4A variants in the proband, her sister, her daughter and her parents. Finally, the phenotypic features of the patient were analyzed, and the current literature was reviewed to better understand the gene variants in PCD related to hearing loss and the clinical manifestations of the RSPH4A variant in PCD. Results: The chief clinical symptoms of this proband included gradual mixed hearing loss, otitis media, anosmia, sinusitis, recurrent cough and infertility. Her DNA sequencing revealed a novel homozygous T to C transition at position 1321 within exon 3 of RSPH4A according to genetic testing results. This variant had never been reported before. The homozygous variant resulted in an amino acid substitution of tryptophan by arginine at position 441 (p.Trp441Arg). The same variant was also found in the proband's sister, and a heterozygous pathogenic variant was identified among immediate family members, including the proband's daughter and parents. Discussion: A literature review showed that 16 pathogenic variants in RSPH4A have been reported. Hearing loss had only been observed in patients with the RSPH4A (c.921+3_6delAAGT) splice site mutation, and the specific type of hearing loss was not described.

FOXJ1 Variants Causing Primary Ciliary Dyskinesia with Hydrocephalus: A Case Report from Japan

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by motile cilia dysfunction, mostly inherited in an autosomal recessive or X-linked manner. We herein report a 29-year-old woman with PCD caused by a heterozygous frameshift mutation due to a single nucleotide deletion in exon 3 of FOXJ1. Heterozygous de novo mutations in FOXJ1 have been reported as an autosomal-dominant cause of PCD. The patient had situs inversus, congenital heart disease, infertility, and hydrocephalus. However, the nasal nitric oxide level was normal. Long-term macrolide therapy was remarkably effective. This is the first case report of PCD caused by a FOXJ1 variant in Japan.

Meta-analysis of Transcriptomic Data from Lung Autopsy and Cellular Models of SARS-CoV-2 Infection

Severe COVID-19 is a systemic disorder involving excessive inflammatory response, metabolic dysfunction, multi-organ damage, and several clinical features. Here, we performed a transcriptome meta-analysis investigating genes and molecular mechanisms related to COVID-19 severity and outcomes. First, transcriptomic data of cellular models of SARS-CoV-2 infection were compiled to understand the first response to the infection. Then, transcriptomic data from lung autopsies of patients deceased due to COVID-19 were compiled to analyze altered genes of damaged lung tissue. These analyses were followed by functional enrichment analyses and gene-phenotype association. A biological network was constructed using the disturbed genes in the lung autopsy meta-analysis. Central genes were defined considering closeness and betweenness centrality degrees. A sub-network phenotype-gene interaction analysis was performed. The meta-analysis of cellular models found genes mainly associated with cytokine signaling and other pathogen response pathways. The meta-analysis of lung autopsy tissue found genes associated with coagulopathy, lung fibrosis, multi-organ damage, and long COVID-19. Only genes DNAH9 and FAM216B were found perturbed in both meta-analyses. BLNK, FABP4, GRIA1, ATF3, TREM2, TPPP, TPPP3, FOS, ALB, JUNB, LMNA, ADRB2, PPARG, TNNC1, and EGR1 were identified as central elements among perturbed genes in lung autopsy and were found associated with several clinical features of severe COVID-19. Central elements were suggested as interesting targets to investigate the relation with features of COVID-19 severity, such as coagulopathy, lung fibrosis, and organ damage.

Dynein axonemal heavy chain 10 deficiency causes primary ciliary dyskinesia in humans and mice

Primary ciliary dyskinesia (PCD) is a congenital, motile ciliopathy with pleiotropic symptoms. Although nearly 50 causative genes have been identified, they only account for approximately 70% of definitive PCD cases. Dynein axonemal heavy chain 10 (DNAH10) encodes a subunit of the inner arm dynein heavy chain in motile cilia and sperm flagella. Based on the common axoneme structure of motile cilia and sperm flagella, DNAH10 variants are likely to cause PCD. Using exome sequencing, we identified a novel DNAH10 homozygous variant (c.589C > T, p.R197W) in a patient with PCD from a consanguineous family. The patient manifested sinusitis, bronchiectasis, situs inversus, and asthenoteratozoospermia. Immunostaining analysis showed the absence of DNAH10 and DNALI1 in the respiratory cilia, and transmission electron microscopy revealed strikingly disordered axoneme 9+2 architecture and inner dynein arm defects in the respiratory cilia and sperm flagella. Subsequently, animal models of Dnah10-knockin mice harboring missense variants and Dnah10-knockout mice recapitulated the phenotypes of PCD, including chronic respiratory infection, male infertility, and hydrocephalus. To the best of our knowledge, this study is the first to report DNAH10 deficiency related to PCD in human and mouse models, which suggests that DNAH10 recessive mutation is causative of PCD.

A novel mutation in PCD-associated gene DNAAF3 causes male infertility due to asthenozoospermia

Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive disease manifested with recurrent infections of respiratory tract and infertility. DNAAF3 is identified as a novel gene associated with PCD and different mutations in DNAAF3 results in different clinical features of PCD patients, such as situs inversus, sinusitis and bronchiectasis. However, the sperm phenotypic characteristics of PCD males are generally poorly investigated. Our reproductive medicine centre received a case of PCD patient with infertility, who presented with sinusitis, recurrent infections of the lower airway and severe asthenozoospermia; However, no situs inversus was found in the patient. A novel homozygous mutation in DNAAF3(c.551T>A; p.V184E) was identified in the PCD patient by whole-exome sequencing. Subsequent Sanger sequencing further confirmed that the DNAAF3 had a homozygous missense variant in the fifth exon. Transmission electron microscopy and immunostaining analysis of the sperms from the patient showed a complete absence of outer dynein arms and partial absence of inner dynein arms, which resulted in the reduction in sperm motility. However, this infertility was overcome by intracytoplasmic sperm injections, as his wife achieved successful pregnancy. These findings showed that the PCD-associated pathogenic mutation within DNAAF3 also causes severe asthenozoospermia and male infertility ultimately due to sperm flagella axoneme defect in humans. Our study not only contributes to understand the sperm phenotypic characteristics of patients with DNAAF3 mutations but also expands the spectrum of DNAAF3 mutations and may contribute to the genetic diagnosis and therapy for infertile patient with PCD.

Morphological Observation and Transcriptome Analysis of Ciliogenesis in Urechis unicinctus (Annelida, Echiura)

During the early development of marine invertebrates, planktic larvae usually occur, and their body surfaces often form specific types of cilia that are involved in locomotion and feeding. The echiuran worm Urechis unicinctus sequentially undergoes the formation and disappearance of different types of body surface cilia during embryonic and larval development. The morphological characteristics and molecular mechanisms involved in the process remain unclear. In this study, we found that body surface cilia in U. unicinctus embryos and larvae can be distinguished into four types: body surface short cilia, apical tufts, circumoral cilia and telotrochs. Further, distribution and genesis of the body surface cilia were characterized using light microscope and electron microscope. To better understand the molecular mechanism during ciliogenesis, we revealed the embryonic and larval transcriptome profile of the key stages of ciliogenesis in U. unicinctus using RNA-Seq technology. A total of 29,158 differentially expressed genes (DEGs) were obtained from 24 cDNA libraries by RNA-Seq. KEGG pathway enrichment results showed that Notch, Wnt and Ca²⁺ signaling pathways were significantly enriched during the occurrence of apical tufts and circumoral cilia. Furthermore, all DEGs were classified according to their expression pattern, and DEGs with similar expression pattern were grouped into a module. All DEG co-expression modules were correlated with traits (body surface short cilia, apical tufts, circumoral cilia and telotrochs) by WGCNA, the results showed DEGs were divided into 13 modules by gene expression patterns and that the genes in No. 7, No. 8 and No. 10 modules were to be highly correlated with the occurrence of apical tufts, circumoral cilia and telotrochs. The top 10 hub genes in the above three modules were identified to be highly correlated with ciliogenesis, including the reported cilium-related gene Cnbd2 and unreported cilium-related candidate genes FAM181B, Capsl, Chst3, TMIE and Innexin. Notably, Innexin was included in the top10 hub genes of the two modules (No. 7 and No. 8), suggesting that Innexin may play an important role in U. unicinctus apical tufts, circumoral cilia and telotrochs genesis. This study revealed the characteristics of ciliogenesis on the body surface of U. unicinctus embryos and larvae, providing basic data for exploring the molecular mechanism of ciliogenesis on the body surface.

LRRC6 regulates biogenesis of motile cilia by aiding FOXJ1 translocation into the nucleus

BACKGROUND

LRRC6 is an assembly factor for dynein arms in the cytoplasm of motile ciliated cells, and when mutated, dynein arm components remained in the cytoplasm. Here, we demonstrate the role of LRRC6 in the active nuclear translocation of FOXJ1, a master regulator for cilia-associated gene transcription.

METHODS

We generated Lrrc6 knockout (KO) mice, and we investigated the role of LRRC6 on ciliopathy development by using proteomic, transcriptomic, and immunofluorescence analysis. Experiments on mouse basal cell organoids confirmed the biological relevance of our findings.

RESULTS

The absence of LRRC6 in multi-ciliated cells hinders the assembly of ODA and IDA components of cilia; in this study, we showed that the overall expression of proteins related to cilia decreased as well. Expression of cilia-related transcripts, specifically ODA and IDA components, dynein axonemal assembly factors, radial spokes, and central apparatus was lower in Lrrc6 KO mice than in wild-type mice. We demonstrated that FOXJ1 was present in the cytoplasm and translocated into the nucleus when LRRC6 was expressed and that this process was blocked by INI-43, an importin α inhibitor.

CONCLUSIONS

Taken together, these results hinted at the LRRC6 transcriptional regulation of cilia-related genes via the nuclear translocation of FOXJ1. Video Abstract.

The effect of Dnaaf5 gene dosage on primary ciliary dyskinesia phenotypes

DNAAF5 is a dynein motor assembly factor associated with the autosomal heterogenic recessive condition of motile cilia, primary ciliary dyskinesia (PCD). The effects of allele heterozygosity on motile cilia function are unknown. We used CRISPR-Cas9 genome editing in mice to recreate a human missense variant identified in patients with mild PCD and a second, frameshift-null deletion in Dnaaf5. Litters with Dnaaf5 heteroallelic variants showed distinct missense and null gene dosage effects. Homozygosity for the null Dnaaf5 alleles was embryonic lethal. Compound heterozygous animals with the missense and null alleles showed severe disease manifesting as hydrocephalus and early lethality. However, animals homozygous for the missense mutation had improved survival, with partially preserved cilia function and motor assembly observed by ultrastructure analysis. Notably, the same variant alleles exhibited divergent cilia function across different multiciliated tissues. Proteomic analysis of isolated airway cilia from mutant mice revealed reduction in some axonemal regulatory and structural proteins not previously reported in DNAAF5 variants. Transcriptional analysis of mouse and human mutant cells showed increased expression of genes coding for axonemal proteins. These findings suggest allele-specific and tissue-specific molecular requirements for cilia motor assembly that may affect disease phenotypes and clinical trajectory in motile ciliopathies.

BBOF1 is required for sperm motility and male fertility by stabilizing the flagellar axoneme in mice

The sperm flagellum is a specialized type of motile cilium composed of a typical "9 + 2" axonemal structure with peri-axonemal structures, such as outer dense fibers (ODFs). This flagellar arrangement is crucial for sperm movement and fertilization. However, the association of axonemal integrity with ODFs remains poorly understood. Here, we demonstrate that mouse BBOF1 could interact with both MNS1, an axonemal component, and ODF2, an ODF protein, and is required for sperm flagellar axoneme maintenance and male fertility. BBOF1 is expressed exclusively in male germ cells from the pachytene stage onwards and is detected in sperm axoneme fraction. Spermatozoa derived from Bbof1-knockout mice exhibit a normal morphology, however, reduced motility due to the absence of certain microtubule doublets, resulting in the failure to fertilize mature oocytes. Furthermore, BBOF1 is found to interact with ODF2 and MNS1 and is also required for their stability. Our findings in mice suggest that Bbof1 could also be essential for human sperm motility and male fertility, thus is a novel potential candidate gene for asthenozoospermia diagnosis.

Schmidtea mediterranea as a Model Organism to Study the Molecular Background of Human Motile Ciliopathies

Cilia and flagella are evolutionarily conserved organelles that form protrusions on the surface of many growth-arrested or differentiated eukaryotic cells. Due to the structural and functional differences, cilia can be roughly classified as motile and non-motile (primary). Genetically determined dysfunction of motile cilia is the basis of primary ciliary dyskinesia (PCD), a heterogeneous ciliopathy affecting respiratory airways, fertility, and laterality. In the face of the still incomplete knowledge of PCD genetics and phenotype-genotype relations in PCD and the spectrum of PCD-like diseases, a continuous search for new causative genes is required. The use of model organisms has been a great part of the advances in understanding molecular mechanisms and the genetic basis of human diseases; the PCD spectrum is not different in this respect. The planarian model (Schmidtea mediterranea) has been intensely used to study regeneration processes, and-in the context of cilia-their evolution, assembly, and role in cell signaling. However, relatively little attention has been paid to the use of this simple and accessible model for studying the genetics of PCD and related diseases. The recent rapid development of the available planarian databases with detailed genomic and functional annotations prompted us to review the potential of the S. mediterranea model for studying human motile ciliopathies.

The effect of Dnaaf5 gene dosage on primary ciliary dyskinesia phenotypes

DNAAF5 is a dynein motor assembly factor associated with the autosomal heterogenic recessive condition of motile cilia, primary ciliary dyskinesia (PCD). The effects of allele heterozygosity on motile cilia function are unknown. We used CRISPR-Cas9 genome editing in mice to recreate a human missense variant identified in patients with mild PCD and a second, frameshift null deletion in Dnaaf5 . Litters with Dnaaf5 heteroallelic variants showed distinct missense and null gene dosage effects. Homozygosity for the null Dnaaf5 alleles was embryonic lethal. Compound heterozygous animals with the missense and null alleles showed severe disease manifesting as hydrocephalus and early lethality. However, animals homozygous for the missense mutation had improved survival, with partial preserved cilia function and motor assembly observed by ultrastructure analysis. Notably, the same variant alleles exhibited divergent cilia function across different multiciliated tissues. Proteomic analysis of isolated airway cilia from mutant mice revealed reduction in some axonemal regulatory and structural proteins not previously reported in DNAAF5 variants. While transcriptional analysis of mouse and human mutant cells showed increased expression of genes coding for axonemal proteins. Together, these findings suggest allele-specific and tissue-specific molecular requirements for cilia motor assembly that may affect disease phenotypes and clinical trajectory in motile ciliopathies.

Brief Summary

A mouse model of human DNAAF5 primary ciliary dyskinesia variants reveals gene dosage effects of mutant alleles and tissue-specific molecular requirements for cilia motor assembly.

Molecular characteristics and transcriptional regulatory of spermatogenesis-related gene RFX2 in adult Banna mini-pig inbred line (BMI)

RFX2 plays critical roles in mammalian spermatogenesis and cilium maturation. Here, the testes of 12-month-old adult boars of Banna mini-pig inbred line (BMI) were subjected to whole-transcriptome sequencing. The results indicated that the average expression (raw count) of RFX2 gene in BMI testes was 16138.25, and the average expression value of the corresponding transcript ENSSSCT00000043271.2 was 123.1898. The CDS of RFX2 obtained from BMI testes was 2,817 bp (GenBank accession number: OL362242). Gene structure analysis showed that RFX2 was located on chromosome 2 of the pig genome with 19 exons. Protein structure analysis indicated that RFX2 contains 728 amino acids with two conserved domains. Phylogenetic analysis revealed that RFX2 was highly conserved with evolutionary homologies among mammalian species. Other analyses, including PPI networks, KEGG, and GO, indicated that BMI RFX2 had interactions with 43 proteins involving various functions, such as in cell cycle, spermatid development, spermatid differentiation, cilium assembly, and cilium organization, etc. Correlation analysis between these proteins and the transcriptome data implied that RFX2 was significantly associated with FOXJ1, DNAH9, TMEM138, E2F7, and ATR, and particularly showed the highest correlation with ATR, demonstrating the importance of RFX2 and ART in spermatogenesis. Functional annotation implied that RFX2 was involved in 17 GO terms, including three cellular components (CC), six molecular functions (MF), and eight biological processes (BP). The analysis of miRNA-gene targeting indicated that BMI RFX2 was mainly regulated by two miRNAs, among which four lncRNAs and five lncRNAs competitively bound ssc-miR-365-5p and ssc-miR-744 with RFX2, respectively. Further, the dual-luciferase report assay indicated that the ssc-miR-365-5p and ssc-miR-744 significantly reduced luciferase activity of RFX2 3'UTR in the 293T cells, suggesting that these two miRNAs regulated the expression of RFX2. Our results revealed the important role of RFX2 in BMI spermatogenesis, making it an intriguing candidate for follow-up studies.

Homozygous mutation in DNAAF4 causes primary ciliary dyskinesia in a Chinese family

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder that affects the structure and function of motile cilia, leading to classic clinical phenotypes, such as situs inversus, chronic sinusitis, bronchiectasis, repeated pneumonia and infertility. In this study, we diagnosed a female patient with PCD who was born in a consanguineous family through classic clinical manifestations, transmission electron microscopy and immunofluorescence staining. A novel DNAAF4 variant NM_130810: c.1118G>A (p. G373E) was filtered through Whole-exome sequencing. Subsequently, we explored the effect of the mutation on DNAAF4 protein from three aspects: protein expression, stability and interaction with downstream DNAAF2 protein through a series of experiments, such as transfection of plasmids and Co-immunoprecipitation. Finally, we confirmed that the mutation of DNAAF4 lead to PCD by reducing the stability of DNAAF4 protein, but the expression and function of DNAAF4 protein were not affected.

Genetic diagnosis for adult patients at a genetic clinic

Clinical utility of genetic testing has rapidly increased in the past decade to identify the definitive diagnosis, etiology, and specific management. The majority of patients receiving testing are children. There are several barriers for genetic tests in adult patients; barriers may arise from either patients or clinicians. Our study aims to realize the detection rate and the benefits of genetic tests in adults. We conducted a prospective study of 10 adult patients who were referred to a genetic clinic. Exome sequencing (ES) was pursued in all cases, and chromosomal microarray (CMA) was performed for six cases. Our result is impressive; six cases (60%) received likely pathogenic and pathogenic variants. Four definitive diagnosis cases had known pathogenic variants in KCNJ2, TGFBR1, SCN1A, and FBN1, whereas another two cases revealed novel likely pathogenic and pathogenic variants in GNB1 and DNAH9. Our study demonstrates the success in genetic diagnosis in adult patients: four cases with definitive, two cases with possible, and one case with partial diagnosis. The advantage of diagnosis is beyond obtaining the diagnosis itself, but also relieving any doubt for the patient regarding any previous questionable diagnosis, guide for management, and recurrence risk in their children or family members. Therefore, this supports the value of genetic testing in adult patients.

Clustering of Genetic Anomalies of Cilia Outer Dynein Arm and Central Apparatus in Patients with Transposition of the Great Arteries

Transposition of the great arteries (TGA) is a congenital heart defect with a complex pathogenesis that has not been fully elucidated. In this study, we performed whole-exome sequencing (WES) in isolated TGA-diagnosed patients and analyzed genes of motile and non-motile cilia ciliogenesis and ciliary trafficking, as well as genes previously associated with this heart malformation. Deleterious missense and splicing variants of genes DNAH9, DNAH11, and ODAD4 of cilia outer dynein arm and central apparatus, HYDIN, were found in our TGA patients. Remarkable, there is a clustering of deleterious genetic variants in cilia genes, suggesting it could be an oligogenic disease. Our data evidence the genetic diversity and etiological complexity of TGA and point out that population allele determination and genetic aggregation studies are required to improve genetic counseling.

Whole-Genome Profile of Greek Patients with Teratozοοspermia: Identification of Candidate Variants and Genes

Male infertility is a global health problem that affects a large number of couples worldwide. It can be categorized into specific subtypes, including teratozoospermia. The present study aimed to identify new variants associated with teratozoospermia in the Greek population and to explore the role of genes on which these were identified. For this reason, whole-genome sequencing (WGS) was performed on normozoospermic and teratozoospermic individuals, and after selecting only variants found in teratozoospermic men, these were further prioritized using a wide range of tools, functional and predictive algorithms, etc. An average of 600,000 variants were identified, and of them, 61 were characterized as high impact and 153 as moderate impact. Many of these are mapped in genes previously associated with male infertility, yet others are related for the first time to teratozoospermia. Furthermore, pathway enrichment analysis and Gene ontology (GO) analyses revealed the important role of the extracellular matrix in teratozoospermia. Therefore, the present study confirms the contribution of genes studied in the past to male infertility and sheds light on new molecular mechanisms by providing a list of variants and candidate genes associated with teratozoospermia in the Greek population.

Potential role of dynein-related genes in the etiology of male infertility: A systematic review and a meta-analysis

BACKGROUND

The dynein-related genes may have a role in the etiology of male infertility, particularly in cases of impaired sperm motility.

OBJECTIVES

The goal of this review is to compile a list of the most important dynein-related candidate genes that may contribute to male factor infertility.

MATERIALS AND METHODS

Databases were searched using the keywords "dynein", "male", "infertility" and by applying strict inclusion criteria. A meta-analysis was also performed by using the eligible case-control studies. The odd ratios (OR), the Z-test score, and the level of significance were determined using a fixed model with a p value of 0.05. Funnel plots were used to check for publication bias.

RESULTS

There were 35 studies that met the inclusion criteria. There were a total of fifteen genes responsible for the production of dynein structural proteins, the production of dynein assembling factors, and potentially associated with male infertility. A total of five case-control studies were eligible for inclusion in the meta-analysis. Variants in the dynein-related genes were linked to an increased the risk of male infertility (OR = 21.52, 95% Confidence Interval (CI) 8.34 - 55.50, Z test = 6.35, p < 0.05). The percentage of heterogeneity, I² , was 47.00%. The lack of variants in the dynein genes was an advantage and this was statistically significant.

DISCUSSION

The results from the present review illustrate that pathogenic variants in genes both for dynein synthesis and for dynein assembly factors could be associated with isolated cases of male infertility without any other symptoms.

CONCLUSIONS

The genes addressed in this study, which are involved in both the production and assembly of dynein, could be used as molecular targets for future research into the etiology of sperm motility problems. This article is protected by copyright. All rights reserved.

Genomic testing for copy number and single nucleotide variants in spermatogenic failure

PURPOSE

To identify clinically significant genomic copy number (CNV) and single nucleotide variants (SNV) in males with unexplained spermatogenic failure (SPGF).

MATERIALS AND METHODS

Peripheral blood DNA from 97/102 study participants diagnosed with oligozoospermia, severe oligozoospermia, or non-obstructive azoospermia (NOA) was analyzed for CNVs via array comparative genomic hybridization (aCGH) and SNVs using whole-exome sequencing (WES).

RESULTS

Of the 2544 CNVs identified in individuals with SPGF, > 90% were small, ranging from 0.6 to 75 kb. Thirty, clinically relevant genomic aberrations, were detected in 28 patients (~ 29%). These included likely diagnostic CNVs in 3/41 NOA patients (~ 7%): 1 hemizygous, intragenic TEX11 deletion, 1 hemizygous DDX53 full gene deletion, and 1 homozygous, intragenic STK11 deletion. High-level mosaicism for X chromosome disomy (~ 10% 46,XY and ~ 90% 47,XXY) was also identified in 3 of 41 NOA patients who previously tested normal with conventional karyotyping. The remaining 24 CNVs detected were heterozygous, autosomal recessive carrier variants. Follow-up WES analysis confirmed 8 of 27 (30%) CNVs (X chromosome disomy excluded). WES analysis additionally identified 13 significant SNVs and/or indels in 9 patients (~ 9%) including X-linked AR, KAL1, and NR0B1 variants.

CONCLUSION

Using a combined genome-wide aCGH/WES approach, we identified pathogenic and likely pathogenic SNVs and CNVs in 15 patients (15%) with unexplained SPGF. This value equals the detection rate of conventional testing for aneuploidies and is considerably higher than the prevalence of Y chromosome microdeletions. Our results underscore the importance of comprehensive genomic analysis in emerging diagnostic testing of complex conditions like male infertility.

GJA1 depletion causes ciliary defects by affecting Rab11 trafficking to the ciliary base

The gap junction complex functions as a transport channel across the membrane. Among gap junction subunits, gap junction protein α1 (GJA1) is the most commonly expressed subunit. A recent study showed that GJA1 is necessary for the maintenance of motile cilia; however, the molecular mechanism and function of GJA1 in ciliogenesis remain unknown. Here, we examined the functions of GJA1 during ciliogenesis in human retinal pigment epithelium-1 and Xenopus laevis embryonic multiciliated-cells. GJA1 localizes to the motile ciliary axonemes or pericentriolar regions beneath the primary cilium. GJA1 depletion caused malformation of both the primary cilium and motile cilia. Further study revealed that GJA1 depletion affected several ciliary proteins such as BBS4, CP110, and Rab11 in the pericentriolar region and basal body. Interestingly, CP110 removal from the mother centriole was significantly reduced by GJA1 depletion. Importantly, Rab11, a key regulator during ciliogenesis, was immunoprecipitated with GJA1, and GJA1 knockdown caused the mislocalization of Rab11. These findings suggest that GJA1 regulates ciliogenesis by interacting with the Rab11-Rab8 ciliary trafficking pathway.

Functional Evaluation and Genetic Landscape of Children and Young Adults Referred for Assessment of Bronchiectasis

Bronchiectasis is the abnormal dilation of the airway which may be caused by various etiologies in children. Beyond the more recognized cause of bacterial and viral infections and primary immunodeficiencies, other genetic conditions such as cystic fibrosis and primary ciliary dyskinesia (PCD) can also contribute to the disease. Currently, there is still debate on whether genome sequencing (GS) or exome sequencing reanalysis (rES) would be beneficial if the initial targeted testing results returned negative. This study aims to provide a back-to-back comparison between rES and GS to explore the best integrated approach for the functional and genetics evaluation for patients referred for assessment of bronchiectasis. In phase 1, an initial 60 patients were analyzed by exome sequencing (ES) with one additional individual recruited later as an affected sibling for ES. Functional evaluation of the nasal nitric oxide test, transmission electron microscopy, and high-speed video microscopy were also conducted when possible. In phase 2, GS was performed on 30 selected cases with trio samples available. To provide a back-to-back comparison, two teams of genome analysts were alternatively allocated to GS or rES and were blinded to each other’s analysis. The time for bioinformatics, analysis, and diagnostic utility was recorded for evaluation. ES revealed five positive diagnoses (5/60, 8.3%) in phase 1, and four additional diagnoses were made by rES and GS (4/30, 13%) during phase 2. Subsequently, one additional positive diagnosis was identified in a sibling by ES and an overall diagnostic yield of 10/61 (16.4%) was reached. Among those patients with a clinical suspicion of PCD (n = 31/61), the diagnostic yield was 26% (n = 8/31). While GS did not increase the diagnostic yield, we showed that a variant of uncertain significance could only be detected by GS due to improved coverage over ES and hence is a potential benefit for GS in the future. We show that genetic testing is an essential component for the diagnosis of early-onset bronchiectasis and is most effective when used in combination with functional tools such as TEM or HSVM. Our comparison of rES vs. GS suggests that rES and GS are comparable in clinical diagnosis.

Pathogenic Variants in Cardiomyopathy Disorder Genes Underlie Pediatric Myocarditis—Further Impact of Heterozygous Immune Disorder Gene Variants?

Myocarditis is an inflammatory disease of the heart. Pediatric myocarditis with the dilated cardiomyopathy (DCM) phenotype may be caused by likely pathogenic or pathogenic genetic variants [(L)P] in cardiomyopathy (CMP) genes. Systematic analysis of immune disorder gene defects has not been performed so far. We analyzed 12 patients with biopsy-proven myocarditis and the DCM phenotype together with their parents using whole-exome sequencing (WES). The WES data were filtered for rare pathogenic variants in CMP (n = 89) and immune disorder genes (n = 631). Twelve children with a median age of 2.9 (1.0–6.8) years had a mean left ventricular ejection fraction of 28% (22–32%) and myocarditis was confirmed by endomyocardial biopsy. Patients with primary immunodeficiency were excluded from the study. Four patients underwent implantation of a ventricular assist device and subsequent heart transplantation. Genetic analysis of the 12 families revealed an (L)P variant in the CMP gene in 8/12 index patients explaining DCM. Screening of recessive immune disorder genes identified a heterozygous (L)P variant in 3/12 index patients. This study supports the genetic impact of CMP genes for pediatric myocarditis with the DCM phenotype. Piloting the idea that additional immune-related genetic defects promote myocarditis suggests that the presence of heterozygous variants in these genes needs further investigation. Altered cilium function might play an additional role in inducing inflammation in the context of CMP.

Dnah9 mutant mice and organoid models recapitulate the clinical features of patients with PCD and provide an excellent platform for drug screening

Primary cilia dyskinesia (PCD) is a rare genetic disease caused by ciliary structural or functional defects. It causes severe outcomes in patients, including recurrent upper and lower airway infections, progressive lung failure, and randomization of heterotaxy. To date, although 50 genes have been shown to be responsible for PCD, the etiology remains elusive. Meanwhile, owing to the lack of a model mimicking the pathogenesis that can be used as a drug screening platform, thereby slowing the development of related therapies. In the current study, we identified compound mutation of DNAH9 in a patient with PCD with the following clinical features: recurrent respiratory tract infections, low lung function, and ultrastructural defects of the outer dynein arms (ODAs). Bioinformatic analysis, structure simulation assay, and western blot analysis showed that the mutations affected the structure and expression of DNAH9 protein. Dnah9 knock-down (KD) mice recapitulated the patient phenotypes, including low lung function, mucin accumulation, and increased immune cell infiltration. Immunostaining, western blot, and co-immunoprecipitation analyses were performed to clarify that DNAH9 interacted with CCDC114/GAS8 and diminished their protein levels. Furthermore, we constructed an airway organoid of Dnah9 KD mice and discovered that it could mimic the key features of the PCD phenotypes. We then used organoid as a drug screening model to identify mitochondrial-targeting drugs that can partially elevate cilia beating in Dnah9 KD organoid. Collectively, our results demonstrated that Dnah9 KD mice and an organoid model can recapture the clinical features of patients with PCD and provide an excellent drug screening platform for human ciliopathies.

Case Report: Rare Dynein Axonemal Heavy Chain 9 Mutations in a Han-Chinese Patient With Kartagener Syndrome

A 52-year-old woman presented with respiratory symptoms of productive cough and shortness of breath. She had suffered from repeated pneumonia. The CT scans revealed chronic sinusitis, tree bud signs in pulmonary imaging, and situs inversus. She received a primary diagnosis of Kartagener syndrome of primary ciliary dyskinesia (PCD) and a genetic examination was performed. Compound heterozygous mutations in dynein axonemal heavy chain 9 (DNAH9) were identified, which encoded outer dynein arms (ODAs) components. DNAH9 mutations are relatively rare events in PCD, and this is the first report of PCD patients with DNAH9 mutations in the Chinese population. Further, a literature review of mutations in PCD was conducted.

High Nasal Nitric Oxide, Cilia Analyses and Genotypes in a Retrospective Cohort of Children with Primary Ciliary Dyskinesia

RATIONALE

While children with primary ciliary dyskinesia (PCD) typically have low nasal nitric oxide (nNO), some children with indisputable PCD may have unexplained high nNO levels.

OBJECTIVES

To look for relationships between nNO measures and genetic findings (and cilia motility or ultrastructure when available) in PCD children with a known genotype.

METHODS

We studied retrospectively 73 PCD children (median (range) age 9.5 (2.1 to 18.2) years). nNO was the mean value of a plateau reached while velum was closed (nNO-VC, threshold 77 nL.min-1), or calculated as the average of 5 peaks obtained during tidal breathing (nNO-TB, threshold 40 nL.min-1). Cilia beat was classified either as motile (including dyskinetic pattern) or immotile depending on whether motility was present or absent in all cilia, or as a mixture of motile and immotile cilia. Genotypes were classified as: pathogenic mutations in a gene known to be associated with high nNO (mild genotype); bi-allelic truncating mutations in other genes (severe mutations); putative hypomorphic pathogenic mutation (missense, single amino-acid deletion or moderate splicing mutations) in at least one allele thought to be possibly associated with a residual production of a functional protein.

RESULTS

nNO was above the discriminant threshold in 16/73 (21.9%) children (11 nNO-VC and 5 nNO-TB). High nNO was less frequent in children with severe mutations (2/42) than in those with mild genotypes (7/10) or at least one hypomorphic mutation (7/21)(P < 0.0001). Median [IQR] nNO-VC values (n=60) were significantly different in the three genotypic groups: severe mutations 18 [10;26] nL.min-1 (n=36), possible residual functional protein production (putative hypomorphic mutations) 23 [16;68] nL.min-1 (n=17), and mild genotypes 139 [57;216] nL.min-1 (n=7); P=0.0002. The higher the cilia motility the higher the nNO-VC (16 [10;23], 23 [17;56], and 78 [45;93] nL.min-1 in patients with respectively immotile, dyskinetic motile/immotile, and dyskinetic motile cilia; P<0.0001), while nNO values were scattered across different ultrastructure defects (P = 0.07).

CONCLUSIONS

In PCD children, high nNO values were linked not only to specific genes and but also to potentially hypomorphic mutations in other genes (with possible functional protein production). nNO values increased with the proportion of motile cilia.

Identification of DNAH17 Variants in Han-Chinese Patients With Left–Right Asymmetry Disorders

The formation of left–right asymmetry of the visceral organs is a conserved feature of the human body, and the asymmetry specification of structure and function is precisely orchestrated by multiple regulatory mechanisms. The abnormal results of organ positioning situs arise from defective cilia structure or function during embryogenesis in humans. In this study, we recruited two unrelated Han-Chinese families with left–right asymmetry disorders. The combination of whole-exome sequencing and Sanger sequencing identified two compound heterozygous variants: c.4109C>T and c.9776C>T, and c.612C>G and c.8764C>T in the dynein axonemal heavy chain 17 gene (DNAH17) in two probands with left–right asymmetry disorders. We report for the first time a possible association between DNAH17 gene variants and left–right asymmetry disorders, which is known as a causal gene for asthenozoospermia. Altogether, the findings of our study may enlarge the DNAH17 gene variant spectrum in human left–right asymmetry disorders, pave a way to illustrate the potential pathogenesis of ciliary/flagellar disorders, and provide supplementary explanation for genetic counseling.

Genomics in Egypt: Current Status and Future Aspects

Egypt is the third most densely inhabited African country. Due to the economic burden and healthcare costs of overpopulation, genomic and genetic testing is a huge challenge. However, in the era of precision medicine, Egypt is taking a shift in approach from “one-size-fits all” to more personalized healthcare via advancing the practice of medical genetics and genomics across the country. This shift necessitates concrete knowledge of the Egyptian genome and related diseases to direct effective preventive, diagnostic and counseling services of prevalent genetic diseases in Egypt. Understanding disease molecular mechanisms will enhance the capacity for personalized interventions. From this perspective, we highlight research efforts and available services for rare genetic diseases, communicable diseases including the coronavirus 2019 disease (COVID19), and cancer. The current state of genetic services in Egypt including availability and access to genetic services is described. Drivers for applying genomics in Egypt are illustrated with a SWOT analysis of the current genetic/genomic services. Barriers to genetic service development in Egypt, whether economic, geographic, cultural or educational are discussed as well. The sensitive topic of communicating genomic results and its ethical considerations is also tackled. To understand disease pathogenesis, much can be gained through the advancement and integration of genomic technologies via clinical applications and research efforts in Egypt. Three main pillars of multidisciplinary collaboration for advancing genomics in Egypt are envisaged: resources, infrastructure and training. Finally, we highlight the recent national plan to establish a genome center that will aim to prepare a map of the Egyptian human genome to discover and accurately determine the genetic characteristics of various diseases. The Reference Genome Project for Egyptians and Ancient Egyptians will initialize a new genomics era in Egypt. We propose a multidisciplinary governance system in Egypt to support genomic medicine research efforts and integrate into the healthcare system whilst ensuring ethical conduct of data.

PCD Genes-From Patients to Model Organisms and Back to Humans

Primary ciliary dyskinesia (PCD) is a hereditary genetic disorder caused by the lack of motile cilia or the assembxly of dysfunctional ones. This rare human disease affects 1 out of 10,000-20,000 individuals and is caused by mutations in at least 50 genes. The past twenty years brought significant progress in the identification of PCD-causative genes and in our understanding of the connections between causative mutations and ciliary defects observed in affected individuals. These scientific advances have been achieved, among others, due to the extensive motile cilia-related research conducted using several model organisms, ranging from protists to mammals. These are unicellular organisms such as the green alga Chlamydomonas, the parasitic protist Trypanosoma, and free-living ciliates, Tetrahymena and Paramecium, the invertebrate Schmidtea, and vertebrates such as zebrafish, Xenopus, and mouse. Establishing such evolutionarily distant experimental models with different levels of cell or body complexity was possible because both basic motile cilia ultrastructure and protein composition are highly conserved throughout evolution. Here, we characterize model organisms commonly used to study PCD-related genes, highlight their pros and cons, and summarize experimental data collected using these models.

Clinical phenotypes of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a hereditary disease characterized by airway mucociliary clearance dysfunction. The estimated prevalence of PCD is 1꞉10 000 to 1꞉20 000. The main respiratory manifestations in children are cough, expectoration, chronic rhinitis, sinusitis, and chronic otitis media, while the most common symptoms in adults are chronic sinusitis, bronchiectasis, and infertility. About 50% of patients with certain PCD-related gene variants are combined with situs inversus, and the incidence of congenital heart disease is also high. The pathogenesis behind PCD is that gene variants cause structural or functional disorders of respiratory cilia and motile cilia of other organs, leading to a series of heterogeneous clinical manifestations, which makes it difficult to identify and diagnose PCD. Combining different disease screening tools and understanding the relationship between genotypes and phenotypes may facilitate early diagnosis and treatment for PCD.

Biallelic DNAH9 mutations are identified in Chinese patients with defective left-right patterning and cilia-related complex congenital heart disease

Defective left-right (LR) pattering results in a spectrum of laterality disorders including situs inversus totalis (SIT) and heterotaxy syndrome (Htx). Approximately, 50% of patients with primary ciliary dyskinesia (PCD) displayed SIT. Recessive variants in DNAH9 have recently been implicated in patients with situs inversus. Here, we describe six unrelated family trios and 2 sporadic patients with laterality defects and complex congenital heart disease (CHD). Through whole exome sequencing (WES), we identified compound heterozygous mutations in DNAH9 in the affected individuals of these family trios. Ex vivo cDNA amplification revealed that DNAH9 mRNA expression was significantly downregulated in these patients carrying biallelic DNAH9 mutations, which cause a premature stop codon or exon skipping. Transmission electron microscopy (TEM) analysis identified ultrastructural defects of the outer dynein arms in these affected individuals. dnah9 knockdown in zebrafish lead to the disturbance of cardiac left-right patterning without affecting ciliogenesis in Kupffer's vesicle (KV). By generating a Dnah9 knockout (KO) C57BL/6n mouse model, we found that Dnah9 loss leads to compromised cardiac function. In this study, we identified recessive DNAH9 mutations in Chinese patients with cardiac abnormalities and defective LR pattering.

Fetal Congenital Heart Disease Caused by Compound Heterozygous Mutations in the DNAH9 Gene: A Case Report

Background: Fetal congenital heart disease (CHD) is the most common congenital defect, with an incidence of 0.6–0.8%, accounting for 30–50% of infant congenital disease deaths. The pathogenesis of CHD is still unclear, so an active and effective prenatal diagnosis is very important for the prevention and control of CHD. Herein, a Chinese CHD patient with rare compound heterozygous mutations in the DNAH9 gene was reported, and the 3D structure and functional changes of DNAH9 protein were predicted.

Case presentation: A 23-year-old pregnant woman came to our hospital for prenatal diagnosis at 27 weeks of gestation. Both she and her partner were unaffected. Fetal CHD was detected by ultrasound screening. Copy number variation sequencing (CNV-seq) revealed an 81 kb deletion at chr17p12 (11,486,795–11,568,385), including exons 1–15 of DNAH9 gene, which plays a key role in cardiac development. Then, whole exome sequencing (WES) was used and identified a nonsense mutation (c.10975C&gt;T) in DNAH9, which resulted in the mutation of amino acid 3,659 from glutamine to termination. The 3D mutant protein structures were predicted using SWISS-MODEL and showed structural changes from functional β-sheet and α-helix to termination, respectively.

Conclusion: We describe a case of fetal CHD caused by DNAH9 mutations and provide an effective diagnostic technique for identifying intragenic deletions. This diagnostic process can be implicated in prenatal diagnosis of CHD.

Dynein axonemal heavy chain 9 M4374I variation may have an effect on imatinib mesylate resistance in CML

Chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm caused by a translocation between the breakpoint cluster region (BCR) and Abelson murine leukemia 1 (ABL1) genes. Tyrosine kinase inhibitors (TKIs) are used in the treatment of CML. TKIs, bind the ABL1 kinase domain of hybrid BCR-ABL1 protein and inhibit its function. However, resistance can occur due to the pathogenic variations in the ABL kinase domain or BCR-ABL1-independent mechanisms. In the present study, genetic variations possibly related to imatinib resistance in CML were explored. A total of five single nucleotide polymorphisms [SNPs; MORN2 rs3099950, PTCRA rs9471966, ANKRD35 rs11579366, dynein axonemal heavy chain 9 (DNAH9) rs1990236 and MAGEC1 rs176037] were investigated in imatinib sensitive and in resistant CML patients. Additionally, sequencing of the ABL1 kinase domain was also performed. The frequency of DNAH9 M4374I (NP_001363.2)/M686I (NP_004653.2) (rs1990236) was found to be significantly higher in the imatinib-resistant group. However, the other SNPs did not exhibit any statistically significant differences and no new variant was detected in the ABL1 kinase domain. Considering the frequency difference of the DNAH9 rs1990236 between imatinib-sensitive and imatinib-resistant groups, DNAH9 gene may play a role in TKI resistance. Due to the limited amounts of literature available on this subject, further studies on DNAH9 and related genes may prove to be beneficial for the elucidation of the association between DNAH9 and TKI resistance. Moreover, further larger studies are required to support the current findings. This may aid in the development of novel treatment protocols for patients with CML with DNAH9 genetic polymorphisms.

Diagnosis of primary ciliary dyskinesia: discrepancy according to different algorithms

Background

Diagnosis of primary ciliary dyskinesia (PCD) is challenging since there is no gold standard test. The European Respiratory (ERS) and American Thoracic (ATS) Societies developed evidence-based diagnostic guidelines with considerable differences.

Objective

We aimed to compare the algorithms published by the ERS and the ATS with each other and with our own PCD-UNIBE algorithm in a clinical setting. Our algorithm is similar to the ERS algorithm with additional immunofluorescence staining. Agreement (Cohen's κ) and concordance between the three algorithms were assessed in patients with suspicion of PCD referred to our diagnostic centre.

Results

In 46 out of 54 patients (85%) the final diagnosis was concordant between all three algorithms (30 PCD negative, 16 PCD positive). In eight patients (15%) PCD diagnosis differed between the algorithms. Five patients (9%) were diagnosed as PCD only by the ATS, one (2%) only by the ERS and PCD-UNIBE, one (2%) only by the ATS and PCD-UNIBE, and one (2%) only by the PCD-UNIBE algorithm. Agreement was substantial between the ERS and the ATS (κ=0.72, 95% CI 0.53–0.92) and the ATS and the PCD-UNIBE (κ=0.73, 95% CI 0.53–0.92) and almost perfect between the ERS and the PCD-UNIBE algorithms (κ=0.92, 95% CI 0.80–1.00).

Conclusion

The different diagnostic algorithms lead to a contradictory diagnosis in a considerable proportion of patients. Thus, an updated, internationally harmonised and standardised PCD diagnostic algorithm is needed to improve diagnostics for these discordant cases.

There is no gold standard test for diagnosing PCD. The use of existing diagnostic algorithms leads to contradicting results in many patients (15% in this study). Thus, an updated and internationally harmonised diagnostic guideline is needed.https://bit.ly/2U19Vvq

RaDiCo, the French national research program on rare disease cohorts

BACKGROUND

Rare diseases (RDs) affect nearly 3 million people in France and at least 26-30 million people in Europe. These diseases, which represent a major medical concern, are mainly of genetic origin, often chronic, progressive, degenerative, life threatening and disabling, accounting for more than one third of all deaths occurring during infancy. In this context, there are needs for coordinated information on RDs at national/international levels, based on high quality, interoperable and sharable data. The main objective of the RaDiCo (Rare Disease Cohorts) program, coordinated by Inserm, was the development of RD e-cohorts via a national platform. The cohort projects were selected through a national call in 2014. The e-cohorts are supported by an interoperable platform, equivalent to an infrastructure, constructed on the "cloud computing" principle and in compliance with the European General Data Protection Regulation. It is dedicated to allow a continuous monitoring of data quality and consistency, in line with the French Health Data Hub.

RESULTS

Depending on cohorts, the objectives are to describe the natural history of the studied RD(s), identify the underlying disease genes, establish phenotype-genotype correlations, decipher their pathophysiology, assess their societal and medico-economic impact, and/or identify patients eligible for new therapeutic approaches. Inclusion of prevalent and incident cases started at the end of 2016. As of April 2021, 5558 patients have been included within 13 RD e-cohorts covering 67 diseases integrated in 10 European Reference Networks and contributing to the European Joint Program on RDs. Several original results have been obtained in relation with the secondary objectives of the RaDiCo cohorts. They deal with discovery of new disease genes, assessment of treatment management, deciphering the underlying pathophysiological mechanisms, diagnostic approaches, genotype-phenotype relationships, development and validation of questionnaires relative to disease burden, or methodological aspects.

CONCLUSION

RaDiCo currently hosts 13 RD e-cohorts on a sharable and interoperable platform constructed on the "cloud computing" principle. New RD e-cohorts at the European and international levels are targeted.

Recent advances in human respiratory epithelium models for drug discovery

The respiratory epithelium is intimately associated with the pathophysiologies of highly infectious viral contagions and chronic illnesses such as chronic obstructive pulmonary disorder, presently the third leading cause of death worldwide with a projected economic burden of £1.7 trillion by 2030. Preclinical studies of respiratory physiology have almost exclusively utilised non-humanised animal models, alongside reductionistic cell line-based models, and primary epithelial cell models cultured at an air-liquid interface (ALI). Despite their utility, these model systems have been limited by their poor correlation to the human condition. This has undermined the ability to identify novel therapeutics, evidenced by a 15% chance of success for medicinal respiratory compounds entering clinical trials in 2018. Consequently, preclinical studies require new translational efficacy models to address the problem of respiratory drug attrition. This review describes the utility of the current in vivo (rodent), ex vivo (isolated perfused lungs and precision cut lung slices), two-dimensional in vitro cell-line (A549, BEAS-2B, Calu-3) and three-dimensional in vitro ALI (gold-standard and co-culture) and organoid respiratory epithelium models. The limitations to the application of these model systems in drug discovery research are discussed, in addition to perspectives of the future innovations required to facilitate the next generation of human-relevant respiratory models.

Diagnostics and Management of Male Infertility in Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD), a disease caused by the malfunction of motile cilia, manifests mainly with chronic recurrent respiratory infections. In men, PCD is also often associated with infertility due to immotile sperm. Since causative mutations for PCD were identified in over 50 genes, the role of these genes in sperm development should be investigated in order to understand the effect of PCD mutations on male fertility. Previous studies showed that different dynein arm heavy chains are present in respiratory cilia and sperm flagellum, which may partially explain the variable effects of mutations on airways and fertility. Furthermore, recent studies showed that male reproductive tract motile cilia may play an important part in sperm maturation and transport. In some PCD patients, extremely low sperm counts were reported, which may be due to motile cilia dysfunction in the reproductive tract rather than problems with sperm development. However, the exact roles of PCD genes in male fertility require additional studies, as do the treatment options. In this review, we discuss the diagnostic and treatment options for men with PCD based on the current knowledge.

Emerging Genotype-Phenotype Relationships in Primary Ciliary Dyskinesia

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.

Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited cause of bronchiectasis. The estimated PCD prevalence in children with bronchiectasis is up to 26% and in adults with bronchiectasis is 1 to 13%. Due to dysfunction of the multiple motile cilia of the respiratory tract patients suffer from poor mucociliary clearance. Clinical manifestations are heterogeneous; however, a typical patient presents with chronic productive cough and rhinosinusitis from early life. Other symptoms reflect the multiple roles of motile cilia in other organs and can include otitis media and hearing loss, infertility, situs inversus, complex congenital heart disease, and more rarely other syndromic features such as hydrocephalus and retinitis pigmentosa. Awareness, identification, and diagnosis of a patient with PCD are important for multidisciplinary care and genetic counseling. Diagnosis can be pursued through a multitest pathway which includes the measurement of nasal nitric oxide, sampling the nasal epithelium to assess ciliary function and structure, and genotyping. Diagnosis is confirmed by the identification of a hallmark ultrastructural defect or pathogenic mutations in one of > 45 PCD causing genes. When a diagnosis is established management is centered around improving mucociliary clearance through physiotherapy and treatment of infection with antibiotics. The first international randomized controlled trial in PCD has recently been conducted showing azithromycin is effective in reducing exacerbations. It is likely that evidence-based PCD-specific management guidelines and therapies will be developed in the near future. This article examines prevalence, clinical features, diagnosis, and management of PCD highlighting recent advances in basic science and clinical care.

[Paramecium, a model organism to study ciliogenesis and ciliopathies]

The cilium is a cell extension forming a distinct compartment of eukaryotic cell body with a complex and dynamic structure. This structure is highly conserved across species and ensures various functions as sensory and motility. In humans, ciliary dysfunction results in diseases (ciliopathies) that can affect all organs. Thanks to its complex ciliary structure, the unicellular and ciliated microorganism, Paramecium, constitutes a model of choice not only to study the structure, assembly and function of cilia but also to validate the specific role of mutations of genes linked to the ciliopathies.

Revisiting the Characteristics of Testicular Germ Cell Lines GC-1(spg) and GC-2(spd)ts

Spermatogenesis is a multifaceted and meticulously orchestrated process involving meiosis, chromatin build up, transcriptional and translational hushing, and spermiogenesis. Male germ cell lines GC-1spg (GC-1) and GC-2(spd)ts (GC-2) provide a useful resource to comprehend the molecular events occurring during such a tightly regulated process. Using cDNA microarray, expression profiling of GC-1 and GC-2 cell lines was done to precisely understand their characteristics and uniqueness. Our observations indicate that whilst both the cell lines are indeed of testicular origin, GC-2 is not haploid as was originally thought. Data analysis of the 23,351 transcripts detected in GC-1 and 20,992 in GC-2 cell lines demonstrates an 80% transcript overlap between GC-1 and GC-2 cells and ~ 40% similarity of both with the primary spermatocyte transcriptome. 3152 and 793 transcripts exclusive to GC-1 and GC-2, respectively, were identified. The presence of transcripts for 36 genes was validated in these cell lines including those showing testis-specific expression, as well as genes not reported previously. Overall, this study provides the transcriptome database of GC-1 and GC-2 cells. Analysis of the data demonstrates the transcriptomic transitions between GC-1 and GC-2 thus providing a glimpse to the process of germ cell differentiation from type B spermatogonium into preleptotene spermatocyte.

Bronchiolitis Obliterans and Primary Ciliary Dyskinesia: What Is the Link?

Bronchiolitis obliterans (BO) is a rare form of chronic obstructive lung disease characterized by obliteration of the small airways caused by inflammation and fibrosis. In children, BO most commonly appears following a severe lower respiratory tract infection. This phenomenon has been described as post-infectious BO (PIBO). PIBO presents with dyspnea, tachypnea, and persistent hypoxemia, as well as characteristic radiographic findings on high-resolution CT (HRCT) of the lungs. A few DNAH1 genetic variants have been postulated to have a role in the development of BO in patients with primary ciliary dyskinesia (PCD), but there is limited evidence regarding this, and etiologies are uncertain. PCD is a genetically heterogeneous autosomal recessive disorder characterized by ciliary dysfunction that causes impaired mucociliary clearance, leading to bronchiectasis and recurrent lower respiratory tract infections due to several pathogenic organisms including Pseudomonas aeruginosa. The link between rare PCD genetic variants and BO remains undetermined. We report the first case in Puerto Rico with Pseudomonal PIBO as the initial presentation of PCD; the patient was a four-year-old male. We also engage in a comparison of our case with previously reported cases of PIBO in PCD patients.

Whole-exome sequencing reveals a combination of extremely rare single-nucleotide polymorphism of DNAH9 and RSPH1 genes in a Japanese fetus with situs viscerum inversus

Randomization of left-right body asymmetry, situs viscerum inversus (heterotaxy), is commonly associated with primary ciliary dyskinesia (PCD) resulting from an abnormal ciliary structure, with approximately 50% of PCD patients exhibiting organ laterality defects. I herein report an intrauterine fetal death case, in which an autopsy revealed two lobes of the bilateral lungs as well as heterotaxy of abdominal organs (right-sided spleen and inversion of the alimentary and biliary organs). Whole-exome sequencing (WES) identified a heterozygous single-nucleotide change (c.12775T>C) in exon 68 of the DNAH9 gene, which is a rare single-nucleotide polymorphism (SNP) of rs746081639 and results in the amino acid change of p.C4259R. WES also identified a rare SNP of rs763089682 (c.121G>A) in the RSPH1 gene that causes a heterozygous amino acid alteration of p.G41R. The frequencies of both SNPs, C in rs746081639 and A in rs763089682, are 0.00000824, and a polyphen-2 analysis predicted these amino acid changes to be probably damaging, with a score of 1.000. The combination of extremely rare SNPs in DNAH9 and RSPH1 genes might have been the possible mechanism underlying the development of the laterality defect in the present case.

Implementation of multigene panel NGS diagnosis in the national primary ciliary dyskinesia cohort of Cyprus: An island with a high disease prevalence

We aimed to determine a genetic diagnosis in the national primary ciliary dyskinesia (PCD) cohort of Cyprus, an island with a high disease prevalence. We used targeted next-generation sequencing (NGS) of 39 PCD genes in 48 patients of Greek-Cypriot and other ancestries. We achieved a molecular diagnosis in 74% of the unrelated families tested. We identified 24 different mutations in 11 genes, 12 of which are novel. Homozygosity was more common in Greek-Cypriot than non-Greek-Cypriot patients (88% vs. 46.2%, p = .016). Four mutations (DNAH11:c.5095-2A>G, CFAP300:c.95_103delGCCGGCTCC, TTC25:c.716G>A, RSPH9:c.670+2T>C) were found in 74% of the diagnosed Greek-Cypriot families. Patients with RSPH9 mutations demonstrated higher nasal nitric oxide (57 vs. 15 nl/min, p <.001), higher forced expiratory volume in 1 s (-0.89 vs. -2.37, p = .018) and forced vital capacity (-1.00 vs. -2.16, p = .029) z scores than the rest of the cohort. Targeted multigene-panel NGS is an efficient tool for early diagnosis of PCD, providing insight into genetic disease epidemiology and improved patient stratification.

Identification of a frame shift mutation in the CCDC151 gene in a Han-Chinese family with Kartagener syndrome

Kartagener syndrome (KS), a subtype of primary ciliary dyskinesia (PCD), is characterized by bronchiectasis, chronic sinusitis, male infertility and situs inversus. KS is a genetically heterogeneous disease that is inherited in an autosomal recessive form; however, X-linked inheritance has also been reported. As of this writing [late 2020], at least 34 loci, most of which have known genes, have been reported in the literature as associating with KS. In the present study, we identified a frame shift mutation, c.167delG (p.G56Dfs*26), in the coiled-coil domain containing 151 gene (CCDC151) responsible for KS in a Han-Chinese family. To our knowledge, this is the first report of a CCDC151 c.167delG mutation in the KS patient. These findings may expand the CCDC151 mutation spectrum of KS, and contribute to future genetic counseling and gene-targeted therapy for this disease.

Limitations and opportunities in the pharmacotherapy of ciliopathies

Ciliopathies are a family of rather diverse conditions, which have been grouped based on the finding of altered or dysfunctional cilia, potentially motile, small cellular antennae extending from the surface of postmitotic cells. Cilia-related disorders include embryonically arising conditions such as Joubert, Usher or Kartagener syndrome, but also afflictions with a postnatal or even adult onset phenotype, i.e. autosomal dominant polycystic kidney disease. The majority of ciliopathies are syndromic rather than affecting only a single organ due to cilia being found on almost any cell in the human body. Overall ciliopathies are considered rare diseases. Despite that, pharmacological research and the strive to help these patients has led to enormous therapeutic advances in the last decade. In this review we discuss new treatment options for certain ciliopathies, give an outlook on promising future therapeutic strategies, but also highlight the limitations in the development of therapeutic approaches of ciliopathies.

Novel variants in DNAH9 lead to nonsyndromic severe asthenozoospermia

BACKGROUND

Asthenozoospermia is one of the most common causes of male infertility, and its genetic etiology is poorly understood. DNAH9 is a core component of outer dynein arms in cilia and flagellum. It was reported that variants of DNAH9 (OMIM: 603330) might cause primary ciliary dyskinesia (PCD). However, variants in DNAH9 lead to nonsyndromic severe asthenozoospermia have yet to be reported.

METHODS

Whole exome sequencing (WES) was performed for two individuals with nonsyndromic severe asthenozoospermia from two non-consanguineous families, and Sanger sequencing was performed to verify the identified variants and parental origins. Sperm routine analysis, sperm vitality rate and sperm morphology analysis were performed according the WHO guidelines 2010 (5th edition). Transmission electron microscopy (TEM, TECNAI-10, 80 kV, Philips, Holland) was used to observe ultrastructures of sperm tail. Quantitative realtime-PCR and immunofluorescence staining were performed to detect the expression of DNAH9-mRNA and location of DNAH9-protein. Furthermore, assisted reproductive procedures were applied.

RESULTS

By WES and Sanger sequencing, compound heterozygous DNAH9 (NM_001372.4) variants were identified in the two individuals with nonsyndromic severe asthenozoospermia (F1 II-1: c.302dupT, p.Leu101fs*47 / c.6956A > G, p.Asp2319Gly; F2 II-1: c.6294 T > A, p.Phe2098Leu / c.10571 T > A, p.Leu3524Gln). Progressive rates less than 1% with normal sperm morphology rates and normal vitality rates were found in both of the two subjects. No respiratory phenotypes, situs inversus or other malformations were found by detailed medical history, physical examination and lung CT scans etc. Moreover, the expression of DNAH9-mRNA was significantly decreased in sperm from F1 II-1. And expression of DNAH9 is lower in sperm tail by immunofluorescence staining in F1 II-1 compared with normal control. Notably, by intracytoplasmic sperm injection (ICSI), F1 II-1 and his partner successfully achieved clinical pregnancy.

CONCLUSIONS

We identified DNAH9 as a novel pathogenic gene for nonsyndromic severe asthenospermia, and ICSI can contribute to favorable pregnancy outcomes for these patients.