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Rapid identification of SARS-CoV-2-infected individuals is a cornerstone for the control of virus spread. The sensitivity of SARS-CoV-2 RNA detection by RT-PCR is similar in saliva and nasopharyngeal swabs. Rapid molecular point-of-care tests in saliva could facilitate, broaden and speed up the diagnosis. We conducted a prospective study in two community COVID-19 screening centers to evaluate the performances of a CE-marked RT-LAMP assay (EasyCoV) designed for the detection of SARS-CoV2 RNA from fresh saliva samples, compared to nasopharyngeal RT-PCR, to saliva RT-PCR and to nasopharyngeal antigen testing. Overall, 117 of the 1718 participants (7%) tested positive with nasopharyngeal RT-PCR. Compared to nasopharyngeal RT-PCR, the sensitivity and specificity of the RT-LAMP assay in saliva were 34% and 97%, respectively. The Ct values of nasopharyngeal RT-PCR were significantly lower in the 40 true positive subjects with saliva RT-LAMP (Ct 25.9) than in the 48 false negative subjects with saliva RT-LAMP (Ct 28.4) ( p  = 0.028). Considering six alternate criteria for reference tests, including saliva RT-PCR and nasopharyngeal antigen, the sensitivity of saliva RT-LAMP ranged between 27 and 44%. The detection of SARS-CoV-2 in crude saliva samples with an RT-LAMP assay had a lower sensitivity than nasopharyngeal RT-PCR, saliva RT-PCR and nasopharyngeal antigen testing. Registration number : NCT04578509.

Kallmann syndrome (KS) associates congenital hypogonadism due to gonadotropin-releasing hormone (GnRH) deficiency and anosmia. The genetics of KS involves various modes of transmission, including oligogenic inheritance. Here, we report that Nrp1(sema/sema) mutant mice that lack a functional semaphorin-binding domain in neuropilin-1, an obligatory coreceptor of semaphorin-3A, have a KS-like phenotype. Pathohistological analysis of these mice indeed showed abnormal development of the peripheral olfactory system and defective embryonic migration of the neuroendocrine GnRH cells to the basal forebrain, which results in increased mortality of newborn mice and reduced fertility in adults. We thus screened 386 KS patients for the presence of mutations in SEMA3A (by Sanger sequencing of all 17 coding exons and flanking splice sites) and identified nonsynonymous mutations in 24 patients, specifically, a frameshifting small deletion (D538fsX31) and seven different missense mutations (R66W, N153S, I400V, V435I, T688A, R730Q, R733H). All the mutations were found in heterozygous state. Seven mutations resulted in impaired secretion of semaphorin-3A by transfected COS-7 cells (D538fsX31, R66W, V435I) or reduced signaling activity of the secreted protein in the GN11 cell line derived from embryonic GnRH cells (N153S, I400V, T688A, R733H), which strongly suggests that these mutations have a pathogenic effect. Notably, mutations in other KS genes had already been identified, in heterozygous state, in five of these patients. Our findings indicate that semaphorin-3A signaling insufficiency contributes to the pathogenesis of KS and further substantiate the oligogenic pattern of inheritance in this developmental disorder.

Nasopharyngeal sampling for nucleic acid amplification testing (NAAT) is the standard diagnostic test of coronavirus disease 2019. Our objectives were to assess, in real-life conditions, the diagnostic accuracy of a nasopharyngeal point-of-care antigen (Ag) test and of saliva NAAT for detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in ambulatory care. This was a prospective cohort study from 19 October through 18 December 2020 in two community COVID-19 screening centers in Paris, France. Two nasopharyngeal swabs and one saliva sample were simultaneously collected. Diagnostic accuracies of nasopharyngeal Ag testing and of three saliva NAAT methods were assessed as compared to nasopharyngeal NAAT. A total of 1452 ambulatory children and adults were included. Overall, 129/1443 (9%) participants tested positive on nasopharyngeal NAAT (102/564 [18%] in symptomatic and 27/879 [3%] in asymptomatic participants). Sensitivity was 94%, 23%, 96%, and 94% for the three different protocols of saliva NAAT and for the nasopharyngeal Ag test, respectively. Estimates of specificity were above 95% for all methods. Diagnostic accuracy was similar in symptomatic and asymptomatic individuals. Diagnostic accuracy of nasopharyngeal Ag testing and of saliva NAAT is similar to that of nasopharyngeal NAAT, subject to compliance with specific protocols for saliva. Registration number: NCT04578509

Acrodysostosis is a very rare congenital multisystem condition characterized by skeletal dysplasia with severe brachydactyly, midfacial hypoplasia, and short stature, varying degrees of intellectual disability, and possible resistance to multiple G protein-coupled receptor signalling hormones. Two distinct subtypes are differentiated: acrodysostosis type 1 resulting from defects in protein kinase type 1-α regulatory subunit and acrodysostosis type 2 caused by mutations in phosphodiesterase 4D (PDE4D). Most cases are sporadic. We report on a rare multigenerational familial case of acrodysostosis type 2 due to a novel autosomal dominantly inherited PDE4D mutation. A 3.5-year-old boy presented with short stature, midfacial hypoplasia, severe brachydactyly, developmental delay, and behavioural problems. Laboratory investigations revealed mild thyrotropin resistance. His mother shared some characteristic features, such as midfacial hypoplasia and severe brachydactyly, but did not show short stature, intellectual disability or hormonal resistance. Genetic analysis identified the identical, novel heterozygous missense mutation of the PDE4D gene c.569C>T (p.Ser190Phe) in both patients. This case illustrates the significant phenotypic variability of acrodysostosis even within one family with identical mutations. Hence, a specific clinical diagnosis of acrodysostosis remains challenging because of great interindividual variability and a substantial overlap of the two subtypes as well as with other related Gsα-cAMP-signalling-linked disorders.

Molecular diagnosis of neurofibromatosis type 1 (NF1) is challenging owing to the large size of the tumour suppressor gene NF1, and the lack of mutation hotspots. A somatic alteration of the wild-type NF1 allele is observed in NF1-associated tumours. Genetic heterogeneity in NF1 was confirmed in patients with SPRED1 mutations. Here, we present a targeted next-generation sequencing (NGS) of NF1 and SPRED1 using a multiplex PCR approach (230 amplicons of ∼150 bp) on a PGM sequencer. The chip capacity allowed mixing 48 bar-coded samples in a 4-day workflow. We validated the NGS approach by retrospectively testing 30 NF1-mutated samples, and then prospectively analysed 279 patients in routine diagnosis. On average, 98.5% of all targeted bases were covered by at least 20X and 96% by at least 100X. An NF1 or SPRED1 alteration was found in 246/279 (88%) and 10/279 (4%) patients, respectively. Genotyping throughput was increased over 10 times, as compared with Sanger, with ∼90[euro ] for consumables per sample. Interestingly, our targeted NGS approach also provided quantitative information based on sequencing depth allowing identification of multiexons deletion or duplication. We then addressed the NF1 somatic mutation detection sensitivity in mosaic NF1 patients and tumours.

Kallmann syndrome is a developmental disease that combines hypogonadotropic hypogonadism and anosmia. Putative loss-of-function mutations in PROKR2 or PROK2, encoding prokineticin receptor-2 (a G protein-coupled receptor), and one of its ligands, prokineticin-2, respectively, have recently been reported in approximately 10% of Kallmann syndrome affected individuals. Notably, given PROKR2 mutations were found in the heterozygous, homozygous, or compound heterozygous state in patients, thus raising the question of a possible digenic inheritance of the disease in heterozygous patients. Indeed, one of these patients was also carrying a missense mutation in KAL1 , the gene responsible for the X chromosome-linked form of Kallmann syndrome. Mutations in PROK2 , however, have so far been found only in the heterozygous state. Here, we report on the identification of PROK2 biallelic mutations, that is, a missense mutation, p.R73C, and a frameshift mutation, c.163delA, in two out of 273 patients presenting as sporadic cases. We conclude that PROK2 mutations in the homozygous state account for a few cases of Kallmann syndrome. Moreover, since the same R73C mutation was previously reported in the heterozygous state, and because Prok2 knockout mice exhibit an abnormal phenotype only in the homozygous condition, we predict that patients carrying monoallelic mutations in PROK2 have another disease-causing mutation, presumably in still undiscovered Kallmann syndrome genes.

The frequency of disease-related large rearrangements (referred to as copy-number mutations, CNMs) varies among genes, and search for these mutations has an important place in diagnostic strategies. In recent years, CGH method using custom-designed high-density oligonucleotide-based arrays allowed the development of a powerful tool for detection of alterations at the level of exons and made it possible to provide flexibility through the possibility of modeling chips. The aim of our study was to test custom-designed oligonucleotide CGH array in a diagnostic laboratory setting that analyses several genes involved in various genetic diseases, and to compare it with conventional strategies. To this end, we designed a 12-plex CGH array (135k; 135 000 probes/subarray) (Roche Nimblegen) with exonic and intronic oligonucleotide probes covering 26 genes routinely analyzed in the laboratory. We tested control samples with known CNMs and patients for whom genetic causes underlying their disorders were unknown. The contribution of this technique is undeniable. Indeed, it appeared reproducible, reliable and sensitive enough to detect heterozygous single-exon deletions or duplications, complex rearrangements and somatic mosaicism. In addition, it improves reliability of CNM detection and allows determination of boundaries precisely enough to direct targeted sequencing of breakpoints. All of these points, associated with the possibility of a simultaneous analysis of several genes and scalability 'homemade' make it a valuable tool as a new diagnostic approach of CNMs.