Sensitivity and specificity of heat and moisture exchange filters sampling for SARS-CoV-2 detection in mechanically ventilated COVID-19 patients.

We assessed the sensitivity and specificity of SARS-CoV-2 detection by polymerase chain reaction in heat and moisture exchange filters (HMEF) in mechanically ventilated COVID-19 patients. We showed that testing HMEF might obviate the need for a tracheal sample to affirm that a patient is not ready to end isolation.

Case Report: Co-infection with SARS-CoV-2 and influenza H1N1 in a patient with acute respiratory distress syndrome and a pulmonary sarcoidosis.

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and has been a global public health concern. Co-infection of SARS-CoV-2 and other respiratory syndrome has been rarely reported. We report coinfection of SARS-CoV-2 and 2009 H1N1 Influenza strain in a French patient with pneumonia leading to acute respiratory distress syndrome.  The patient also had a medical history of pulmonary sarcoidosis with a restrictive ventilatory syndrome, which would be a supplementary risk to develop a poor outcomes. This case highlights the possible coinfection of two severe SARS-CoV-2 and influenza H1N1 viruses, which presents a higher risk to extend the care duration. The overlapping clinical features of the two respiratory syndromes is a challenge, and awareness is required to recommend an early differential diagnosis.

A homozygous AHI1 gene mutation (p.Thr304AsnfsX6) in a consanguineous Moroccan family with Joubert syndrome: a case report.

INTRODUCTION: Joubert syndrome is a rare congenital disorder characterized by brain malformation, developmental delay with hypotonia, ocular motor apraxia, and breathing abnormalities. Joubert syndrome is a genetically highly heterogeneous ciliopathy disorder with 23 identified causative genes. The diagnosis is based on brain imaging showing the "molar tooth sign" with cerebellar vermis agenesis. We describe a consanguineous Moroccan family with three affected siblings (18-year-old boy, 13-year-old girl, and 10-year-old boy) showing typical signs of Joubert syndrome, and attempt to identify the underlying genetic defect in this family. METHODS: We performed genome-wide homozygosity mapping using a high-resolution array followed by targeted Sanger sequencing to identify the causative gene. RESULTS: This approach found three homozygous regions, one including the AHI1 gene. Direct sequencing of the 26 coding exons of AHI1 revealed a homozygous mutation (p.Thr304AsnfsX6) located in exon 7 present in the three Joubert syndrome-affected Moroccan siblings. Of more interest, this truncating mutation was previously reported in patients with compound heterozygous Joubert syndrome originating from Spain (one patient) and from the Netherlands (two patients), suggesting a possible founder effect or mutational hotspot. CONCLUSIONS: Combined homozygosity mapping and targeted sequencing allowed the rapid detection of the disease-causing mutation in the AHI1 gene in this family affected with a highly genetically heterogeneous disorder. Carriers of the same truncating mutation (p.Thr304AsnfsX6), originating from Spain and the Netherlands, presented variable clinical characteristics, thereby corroborating the extreme heterogeneity of Joubert syndrome.

Pleiotropic effects of CEP290 (NPHP6) mutations extend to Meckel syndrome.

Meckel syndrome (MKS) is a rare autosomal recessive lethal condition characterized by central nervous system malformations, polydactyly, multicystic kidney dysplasia, and ductal changes of the liver. Three loci have been mapped (MKS1-MKS3), and two genes have been identified (MKS1/FLJ20345 and MKS3/TMEM67), whereas the gene at the MKS2 locus remains unknown. To identify new MKS loci, a genomewide linkage scan was performed using 10-cM-resolution microsatellite markers in eight families. The highest heterogeneity LOD score was obtained for chromosome 12, in an interval containing CEP290, a gene recently identified as causative of Joubert syndrome (JS) and isolated Leber congenital amaurosis. In view of our recent findings of allelism, at the MKS3 locus, between these two disorders, CEP290 was considered a candidate, and homozygous or compound heterozygous truncating mutations were identified in four families. Sequencing of additional cases identified CEP290 mutations in two fetuses with MKS and in four families presenting a cerebro-reno-digital syndrome, with a phenotype overlapping MKS and JS, further demonstrating that MKS and JS can be variable expressions of the same ciliopathy. These data identify a fourth locus for MKS (MKS4) and the CEP290 gene as responsible for MKS.

The ciliary gene RPGRIP1L is mutated in cerebello-oculo-renal syndrome (Joubert syndrome type B) and Meckel syndrome.

Cerebello-oculo-renal syndrome (CORS), also called Joubert syndrome type B, and Meckel (MKS) syndrome belong to the group of developmental autosomal recessive disorders that are associated with primary cilium dysfunction. Using SNP mapping, we identified missense and truncating mutations in RPGRIP1L (KIAA1005) in both CORS and MKS, and we show that inactivation of the mouse ortholog Rpgrip1l (Ftm) recapitulates the cerebral, renal and hepatic defects of CORS and MKS. In addition, we show that RPGRIP1L colocalizes at the basal body and centrosomes with the protein products of both NPHP6 and NPHP4, known genes associated with MKS, CORS and nephronophthisis (a related renal disorder and ciliopathy). In addition, the RPGRIP1L missense mutations found in CORS individuals diminishes the interaction between RPGRIP1L and nephrocystin-4. Our findings show that mutations in RPGRIP1L can cause the multiorgan phenotypic abnormalities found in CORS or MKS, which therefore represent a continuum of the same underlying disorder.

Spectrum of MKS1 and MKS3 mutations in Meckel syndrome: a genotype-phenotype correlation. Mutation in brief #960. Online.

Meckel syndrome (MKS) is a rare autosomal recessive lethal condition characterized by central nervous system malformations (typically occipital meningoencephalocele), postaxial polydactyly, multicystic kidney dysplasia, and ductal proliferation in the portal area of the liver. MKS is genetically heterogeneous and three loci have been mapped respectively on 17q23 (MKS1), 11q13 (MKS2), and 8q24 (MKS3). Very recently, two genes have been identified: MKS1/FLJ20345 on 17q in Finnish kindreds, carrying the same intronic deletion, c.1408-35_c.1408-7del29, and MKS3/TMEM67 on 8q in families from Pakistan and Oman. Here we report the genotyping of the MKS1 and MKS3 genes in a large, multiethnic cohort of 120 independent cases of MKS. Our first results indicate that the MKS1 and MKS3 genes are each responsible for about 7% of MKS cases with various mutations in different populations. A strong phenotype-genotype correlation, depending on the mutated gene, was observed regarding the type of central nervous system malformation, the frequency of polydactyly, bone dysplasia, and situs inversus. The MKS1 c.1408-35_1408-7del29 intronic mutation was identified in three cases from French or English origin and dated back to 162 generations (approx. 4050 years) ago. We also identified a common MKS3 splice-site mutation, c.1575+1G>A, in five Pakistani sibships of three unrelated families of Mirpuri origin, with an estimated age-of-mutation of 5 generations (125 years).

Homozygous silencing of T-box transcription factor EOMES leads to microcephaly with polymicrogyria and corpus callosum agenesis.

Neural progenitor proliferation and migration influence brain size during neurogenesis. We report an autosomal recessive microcephaly syndrome cosegregating with a homozygous balanced translocation between chromosomes 3p and 10q, and we show that a position effect at the breakpoint on chromosome 3 silences the eomesodermin transcript (EOMES), also known as T-box-brain2 (TBR2). Together with the expression pattern of EOMES in the developing human brain, our data suggest that EOMES is involved in neuronal division and/or migration. Thus, mutations in genes encoding not only mitotic and apoptotic proteins but also transcription factors may be responsible for malformative microcephaly syndromes.

The Meckel-Gruber syndrome gene, MKS3, is mutated in Joubert syndrome.

Joubert syndrome (JS) is an autosomal recessive disorder characterized by cerebellar vermis hypoplasia associated with hypotonia, developmental delay, abnormal respiratory patterns, and abnormal eye movements. The association of retinal dystrophy and renal anomalies defines JS type B. JS is a genetically heterogeneous condition with mutations in two genes, AHI1 and CEP290, identified to date. In addition, NPHP1 deletions identical to those that cause juvenile nephronophthisis have been identified in a subset of patients with a mild form of cerebellar and brainstem anomaly. Occipital encephalocele and/or polydactyly have occasionally been reported in some patients with JS, and these phenotypic features can also be observed in Meckel-Gruber syndrome (MKS). MKS is a rare, autosomal recessive lethal condition characterized by central nervous system malformations (typically, occipital meningoencephalocele), postaxial polydactyly, multicystic kidney dysplasia, and ductal proliferation in the portal area of the liver. Since there is obvious phenotypic overlap between JS and MKS, we hypothesized that mutations in the recently identified MKS genes, MKS1 on chromosome 17q and MKS3 on 8q, may be a cause of JS. After mutation analysis of MKS1 and MKS3 in a series of patients with JS (n=22), we identified MKS3 mutations in four patients with JS, thus defining MKS3 as the sixth JS locus (JBTS6). No MKS1 mutations were identified in this series, suggesting that the allelism is restricted to MKS3.

A novel autosomal recessive myopathy with external ophthalmoplegia linked to chromosome 17p13.1-p12.

We describe a new autosomal recessive myopathy of early onset and very slow progression distinguished by the prominent external ophthalmoplegia in 16 subjects of eight families from a large and highly inbred Arab community. Characteristic clinical features include mild facial and skeletal muscle weakness and atrophy more pronounced proximally in the upper limbs, facial dysmorphism and scoliosis associated with conjugate, non-restrictive ocular motility impairment greatest in the upgaze and without ptosis or aberrant eye movements. Orbital MRI in the patients demonstrated atrophy with fatty replacement of the oculorotatory muscles. The major pathological alteration on skeletal muscle biopsy was a marked type 1 fibre predominance with core-like formations. A genome wide search for regions of homozygosity in the affected members from two informative families identified linkage with chromosome 17p13.1-p12 markers. Maximum two-point logarithm of odds scores were obtained at loci D17S1803 and AFMA070WD1 (Zmax = 3.74 at = 0). Two independent recombination events at D17S1812 and D17S947 further defined a critical region of 12 cM. Several genes map to this interval, including a cluster of sarcomeric myosin heavy chain genes. One of these genes, MYH2, is involved in inclusion body myopathy 3, but no exonic mutations were found by direct sequencing. The molecular basis for this new myopathy remains to be identified.

Claudin-1 gene mutations in neonatal sclerosing cholangitis associated with ichthyosis: a tight junction disease.

BACKGROUND AND AIMS: Most human and animal cholestatic disorders are associated with changes in hepatocyte cytoskeleton and tight junctions (TJs). These changes are usually secondary and nonspecific phenomena, both in intra- and extrahepatic cholestasis. Recently, missense mutations in TJ protein 2 (ZO-2) have been identified in patients with familial hypercholanemia. In the liver, TJs separate bile flow from plasma and are composed of strands of claudins and occludin. We previously assigned a syndrome associating ichthyosis and neonatal sclerosing cholangitis (NISCH syndrome) to chromosome 3q27-q28. We considered claudin-1 to be a strong candidate gene based on its mapping to the minimum interval and on the expression pattern of the mouse ortholog. METHODS: The 4 exons and intron-exon junctions of claudin-1 gene were amplified using standard polymerase chain reaction protocols and specific primers. Western blot analysis on cultured fibroblasts and immunohistochemistry on liver tissue section were performed using rabbit anti-claudin-1 antibodies. RESULTS: We described in 4 patients, of 2 inbred kindred of Moroccan origin, a 2-bp deletion (200-201 TT) in exon 1 of the claudin-1 gene arising in a premature stop codon and resulting in total absence of claudin-1 protein in the liver and skin. CONCLUSIONS: Lack of claudin-1 in NISCH syndrome may lead to increased paracellular permeability between epithelial cells. Bile duct injury may be related to the absence of claudin-1 expression in cholangiocytes. Our observation, in conjunction with ZO-2-associated hypercholanemia, emphasizes the role played by TJ components in hereditary cholestasis.

Homozygosity mapping of a locus for a novel syndromic ichthyosis to chromosome 3q27-q28.

Ichthyosis is a heterogeneous group of skin disorders characterized by abnormal epidermal scaling. Occasionally, extracutaneous features are associated. A novel autosomal recessive ichthyosis syndrome is described here with scalp hypotrichosis, scarring alopecia, sclerosing cholangitis, and leukocyte vacuolization in two inbred kindreds of Moroccan origin. We also report the mapping of the diseased gene to a 21.2 cM interval of chromosome 3q27-q28. Homo zygosity for polymorphic markers has enabled us to reduce the genetic interval to a 16.2 cM region. Furthermore, comparison of mutant chromosomes in the two families has suggested a common ancestral mutant haplotype. This linkage disequilibrium has reduced the genetic interval encompassing the diseased gene to less than 9.5 cM maximum. Further study of additional families from the same geographic area will hopefully reduce the genetic interval as well as help in the cloning of the gene involved in this rare disorder.