Primary ciliary dyskinesia (PCD) is an inherited chronic respiratory obstructive disease with randomized body laterality and infertility, resulting from cilia and sperm dysmotility. PCD is ...characterized by clinical variability and extensive genetic heterogeneity, associated with different cilia ultrastructural defects and mutations identified in >20 genes. Next generation sequencing (NGS) technologies therefore present a promising approach for genetic diagnosis which is not yet in routine use. We developed a targeted panel-based NGS pipeline to identify mutations by sequencing of selected candidate genes in 70 genetically undefined PCD patients. This detected loss-of-function RSPH1 mutations in four individuals with isolated central pair (CP) agenesis and normal body laterality, from two unrelated families. Ultrastructural analysis in RSPH1-mutated cilia revealed transposition of peripheral outer microtubules into the 'empty' CP space, accompanied by a distinctive intermittent loss of the central pair microtubules. We find that mutations in RSPH1, RSPH4A and RSPH9, which all encode homologs of components of the 'head' structure of ciliary radial spoke complexes identified in Chlamydomonas, cause clinical phenotypes that appear to be indistinguishable except at the gene level. By high-resolution immunofluorescence we identified a loss of RSPH4A and RSPH9 along with RSPH1 from RSPH1-mutated cilia, suggesting RSPH1 mutations may result in loss of the entire spoke head structure. CP loss is seen in up to 28% of PCD cases, in whom laterality determination specified by CP-less embryonic node cilia remains undisturbed. We propose this defect could arise from instability or agenesis of the ciliary central microtubules due to loss of their normal radial spoke head tethering.
An eosinophilic bronchial inflammation was previously demonstrated in patients with nasal polyposis (NP) and asymptomatic bronchial hyperresponsiveness (BHR) similar to that observed in asthmatic ...patients with NP, whereas patients with NP without BHR did not. The aim of the study was to investigate the contribution of interleukin 5 (IL-5) and eotaxin to the pathogenesis of BHR associated with NP. Eleven patients with NP without BHR (Group A), 8 patients with NP and asymptomatic BHR (Group B), and 9 patients with NP and asthma (Group C) were included. Bronchial biopsies were studied for IL-5 and eotaxin immunoreactivity and IL-5 mRNA expression. IL-5 levels were determined in bronchial lavage (BL). Compared with Groups A and B, Group C patients exhibited higher numbers of IL-5 protein(+) cells, IL-5 mRNA(+) cells, and eotaxin(+) cells in bronchial submucosa. Compared with Group A, Group B patients showed an increased number of IL-5 protein(+) cells, whereas the number of IL-5 mRNA(+) cells and eotaxin(+) cells was similar. IL-5 levels in BL were increased only in Group C. Our study provides evidence of IL-5 involvement in bronchial eosinophilia and in the pathogenesis of asymptomatic BHR associated with NP, whereas both IL-5 and eotaxin are involved in asthma associated with NP.
Background: Nasal polyposis (NP) frequently complicates the course of cystic fibrosis (CF). The aim of this study was to determine the pattern of inflammatory cells and mediators in nasal secretions ...from patients with or without NP compared to patients with idiopathic NP and healthy controls. Methods: Eighteen CF patients with NP (NP+ group: 6 untreated, 12 treated with nasal steroids), and 15 without NP (NP− group) were included in this prospective study and compared to 9 patients with idiopathic NP and 12 healthy controls. Differential cell count eosinophil cationic protein (ECP), interleukin-5 (IL-5) and IL-8 were determined in nasal lavage fluids. Results: The total cell count, the number and the percentage of neutrophils and eosinophils, the levels of IL-8, IL-5 and ECP were significantly higher in nasal secretions from both NP+ and NP− as compared with controls. No difference was found between untreated and treated CF patients with NP. No difference was found between NP+ and NP− groups. Compared to idiopathic NP group, both NP+ and NP− groups had higher percentage of neutrophils and lower percentage of eosinophils. There were no differences according to the use of topical steroids, systemic antibiotherapy, or the type of mutation. CF patients with positive nasal culture had a higher percentage of neutrophils than those with negative culture. CF patients with atopy had a higher percentage of eosinophils than non-atopic patients. Conclusion: Our results demonstrate that nasal inflammation is a prominent feature in patients with CF and does not differ according to the presence of NP. IL-8 and IL-5 may play crucial roles in recruitment and activation of neutrophils and eosinophils in upper airways of CF patients.
Xq28 int22h‐1/int22h‐2 duplication is the result of non‐allelic homologous recombination between int22h‐1/int22h‐2 repeats separated by 0.5 Mb. It is responsible for a syndromic form of intellectual ...disability (ID), with recurrent infections and atopic diseases. Minor defects, nonspecific facial dysmorphic features, and overweight have also been described. Half of female carriers have been reported with ID, whereas all reported evaluated born males present mild to moderate ID, suggesting complete penetrance. We collected data on 15 families from eight university hospitals. Among them, 40 patients, 21 females (one fetus), and 19 males (two fetuses), were carriers of typical or atypical Xq28 int22h‐1/int22h‐2 duplication. Twenty‐one individuals were considered asymptomatic (16 females and 5 males), without significantly higher rate of recurrent infections, atopia, overweight, or facial dysmorphism. Approximately 67% live‐born males and 23% live‐born female carriers of the typical duplication did not have obvious signs of intellectual disability, suggesting previously undescribed incomplete penetrance or low expression in certain carriers. The possibility of a second‐hit or modifying factors to this possible susceptibility locus is yet to be studied but a possible observational bias should be considered in assessing such challenging X‐chromosome copy number gains. Additional segregation studies should help to quantify this newly described incomplete penetrance.
After assembling a French cohort of 15 families with 40 carriers of the Xq28 int22h‐1/int22h‐2 duplication, we found that the penetrance of the associated syndromic intellectual disability was less than 100% in our male individuals and less than 50% in our female individuals, inconsistent with previous descriptions in the literature.
Objective
We aimed to gather fetal cases carrying a 7q11.23 copy number variation (CNV) and collect precise clinical data to broaden knowledge of antenatal features in these syndromes.
Methods
We ...retrospectively recruited unrelated cases with 7q11.23 deletion, known as Williams‐Beuren syndrome (WBS), or 7q11.23 duplication who had prenatal ultrasound findings. We collected laboratory and clinical data, fetal ultrasound, cardiac ultrasound and fetal autopsy reports from 18 prenatal diagnostic centers throughout France.
Results
40 fetuses with WBS were collected and the most common features were intra‐uterine growth retardation (IUGR) (70.0%, 28/40), cardiovascular defects (30.0%, 12/40), polyhydramnios (17.5%, 7/40) and protruding tongue (15.0%, 6/40). Fetal autopsy reports were available for 11 cases and were compared with ultrasound prenatal features. Four cases of fetuses with 7q11.23 microduplication were collected and prenatal ultrasound signs were variable and often isolated.
Conclusion
This work strengthens the fact that 7q11.23 CNVs are associated with a broad spectrum of antenatal presentations. IUGR and cardiovascular defects were the most frequent ultrasound signs. By reporting the biggest series of antenatal WBS, we aim to better delineate distinctive signs in fetuses with 7q11.23 CNVs.
Key points
What is already known on this topic?
Deletion of the 7q11.23 region causes the Williams Beuren syndrome (WBS). The reciprocal duplication is responsible for a distinctive although less severe neurodevelopmental disorder.
Diagnosis of WBS is usually suspected postnatally in infants but its prenatal presentation remains challenging.
What does this study add?
Largest series of fetuses with a 7q11.23 deletion or a 7q11.23 duplication.
Antenatal ultrasound findings of prenatal 7q11.23 copy number variations.
Most of human genome is present in two copies (maternal and paternal). However, segments of the genome can be deleted or duplicated, and many of these genomic variations (known as Copy Number ...Variants) are associated with psychiatric disorders. 16p11.2 copy number variants (breakpoint 4–5) confer high risk for neurodevelopmental disorders and are associated with structural brain alterations of large effect-size. Methods used in previous studies were unable to investigate the onset of these alterations and whether they evolve with age. In this study, we aim at characterizing age-related effects of 16p11.2 copy number variants by analyzing a group with a broad age range including younger individuals. A large normative developmental dataset was used to accurately adjust for effects of age. We normalized volumes of segmented brain regions as well as volumes of each voxel defined by tensor-based morphometry. Results show that the total intracranial volumes, the global gray and white matter volumes are respectively higher and lower in deletion and duplication carriers compared to control subjects at 4.5 years of age. These differences remain stable through childhood, adolescence and adulthood until 23 years of age (range: 0.5 to 1.0 Z-score). Voxel-based results are consistent with previous findings in 16p11.2 copy number variant carriers, including increased volume in the calcarine cortex and insula in deletions, compared to controls, with an inverse effect in duplication carriers (1.0 Z-score). All large effect-size voxel-based differences are present at 4.5 years and seem to remain stable until the age of 23. Our results highlight the stability of a neuroimaging endophenotype over 2 decades during which neurodevelopmental symptoms evolve at a rapid pace.
Although 22q11.2 deletion syndrome (22q11.2DS) is the most recurrent human microdeletion syndrome associated with a highly variable phenotype, little is known about the condition's true incidence and ...the phenotype at diagnosis. We performed a multicenter, retrospective analysis of postnatally diagnosed patients recruited by members of the Association des Cytogénéticiens de Langue Française (the French-Speaking Cytogeneticists Association). Clinical and cytogenetic data on 749 cases diagnosed between 1995 and 2013 were collected by 31 French cytogenetics laboratories. The most frequent reasons for referral of postnatally diagnosed cases were a congenital heart defect (CHD, 48.6%), facial dysmorphism (49.7%) and developmental delay (40.7%). Since 2007 (the year in which array comparative genomic hybridization (aCGH) was introduced for the routine screening of patients with intellectual disability), almost all cases have been diagnosed using FISH (96.1%). Only 15 cases (all with an atypical phenotype) were diagnosed with aCGH; the deletion size ranged from 745 to 2904 kb. The deletion was inherited in 15.0% of cases and was of maternal origin in 85.5% of the latter. This is the largest yet documented cohort of patients with 22q11.2DS (the most commonly diagnosed microdeletion) from the same population. French cytogenetics laboratories diagnosed at least 108 affected patients (including fetuses) per year from among a national population of ∼66 million. As observed for prenatal diagnoses, CHDs were the most frequently detected malformation in postnatal diagnoses. The most common CHD in postnatal diagnoses was an isolated septal defect.
Background Balanced chromosomal rearrangements associated with abnormal phenotype are rare events, but may be challenging for genetic counselling, since molecular characterisation of breakpoints is ...not performed routinely. We used next-generation sequencing to characterise breakpoints of balanced chromosomal rearrangements at the molecular level in patients with intellectual disability and/or congenital anomalies. Methods Breakpoints were characterised by a paired-end low depth whole genome sequencing (WGS) strategy and validated by Sanger sequencing. Expression study of disrupted and neighbouring genes was performed by RT-qPCR from blood or lymphoblastoid cell line RNA. Results Among the 55 patients included (41 reciprocal translocations, 4 inversions, 2 insertions and 8 complex chromosomal rearrangements), we were able to detect 89% of chromosomal rearrangements (49/55). Molecular signatures at the breakpoints suggested that DNA breaks arose randomly and that there was no major influence of repeated elements. Non-homologous end-joining appeared as the main mechanism of repair (55% of rearrangements). A diagnosis could be established in 22/49 patients (44.8%), 15 by gene disruption ( KANSL1 , FOXP1 , SPRED1 , TLK2 , MBD5 , DMD , AUTS2 , MEIS2 , MEF2C , NRXN1 , NFIX , SYNGAP1, GHR, ZMIZ1 ) and 7 by position effect ( DLX5 , MEF2C , BCL11B , SATB2, ZMIZ1 ). In addition, 16 new candidate genes were identified. Systematic gene expression studies further supported these results. We also showed the contribution of topologically associated domain maps to WGS data interpretation. Conclusion Paired-end WGS is a valid strategy and may be used for structural variation characterisation in a clinical setting.
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