IMPORTANCE: Aminoglycosides are commonly prescribed antibiotics used for the treatment of neonatal sepsis. The MT-RNR1 m.1555A>G variant predisposes to profound aminoglycoside-induced ototoxicity ...(AIO). Current genotyping approaches take several days, which is unfeasible in acute settings. OBJECTIVE: To develop a rapid point-of-care test (POCT) for the m.1555A>G variant before implementation of this technology in the acute neonatal setting to guide antibiotic prescribing and avoid AIO. DESIGN, SETTING, AND PARTICIPANTS: This pragmatic prospective implementation trial recruited neonates admitted to 2 large neonatal intensive care units between January 6, 2020, and November 30, 2020, in the UK. INTERVENTIONS: Neonates were tested for the m.1555A>G variant via the rapid POCT on admission to the neonatal intensive care unit. MAIN OUTCOMES AND MEASURES: The primary outcome assessed the proportion of neonates successfully tested for the variant of all infants prescribed antibiotics. Secondary outcomes measured whether implementation was negatively associated with routine clinical practice and the performance of the system. The study was statistically powered to detect a significant difference between time to antibiotic administration before and after implementation of the MT-RNR1 POCT. RESULTS: A total of 751 neonates were recruited and had a median (range) age of 2.5 (0-198) days. The MT-RNR1 POCT was able to genotype the m.1555A>G variant in 26 minutes. Preclinical validation demonstrated a 100% sensitivity (95% CI, 93.9%-100.0%) and specificity (95% CI, 98.5%-100.0%). Three participants with the m.1555A>G variant were identified, all of whom avoided aminoglycoside antibiotics. Overall, 424 infants (80.6%) receiving antibiotics were successfully tested for the variant, and the mean time to antibiotics was equivalent to previous practice. CONCLUSIONS AND RELEVANCE: The MT-RNR1 POCT was integrated without disrupting normal clinical practice, and genotype was used to guide antibiotic prescription and avoid AIO. This approach identified the m.1555A>G variant in a practice-changing time frame, and wide adoption could significantly reduce the burden of AIO.
Human mitochondrial RNase P (mt-RNase P) is responsible for 5′ end processing of mitochondrial precursor tRNAs, a vital step in mitochondrial RNA maturation, and is comprised of three protein ...subunits: TRMT10C, SDR5C1 (HSD10), and PRORP. Pathogenic variants in TRMT10C and SDR5C1 are associated with distinct recessive or x-linked infantile onset disorders, resulting from defects in mitochondrial RNA processing. We report four unrelated families with multisystem disease associated with bi-allelic variants in PRORP, the metallonuclease subunit of mt-RNase P. Affected individuals presented with variable phenotypes comprising sensorineural hearing loss, primary ovarian insufficiency, developmental delay, and brain white matter changes. Fibroblasts from affected individuals in two families demonstrated decreased steady state levels of PRORP, an accumulation of unprocessed mitochondrial transcripts, and decreased steady state levels of mitochondrial-encoded proteins, which were rescued by introduction of the wild-type PRORP cDNA. In mt-tRNA processing assays performed with recombinant mt-RNase P proteins, the disease-associated variants resulted in diminished mitochondrial tRNA processing. Identification of disease-causing variants in PRORP indicates that pathogenic variants in all three subunits of mt-RNase P can cause mitochondrial dysfunction, each with distinct pleiotropic clinical presentations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The bladder exstrophy-epispadias complex (BEEC) is an abdominal midline malformation comprising a spectrum of congenital genitourinary abnormalities of the abdominal wall, pelvis, urinary tract, ...genitalia, anus, and spine. The vast majority of BEEC cases are classified as non-syndromic and the etiology of this malformation is still unknown. This review presents the current knowledge on this multifactorial disorder, including phenotypic and anatomical characterization, epidemiology, proposed developmental mechanisms, existing animal models, and implicated genetic and environmental components.
Urofacial (also called Ochoa) syndrome (UFS) is an autosomal recessive congenital disorder of the urinary bladder featuring voiding dysfunction and a grimace upon smiling. Biallelic variants in
, ...coding for the secreted protein heparanase-2, are described in around half of families genetically studied.
mutant mice have aberrant bladder nerves. We sought to expand the genotypic spectrum of UFS and make insights into its pathobiology. Sanger sequencing, next generation sequencing and microarray analysis were performed in four previously unreported families with urinary tract disease and grimacing. In one, the proband had kidney failure and was homozygous for the previously described pathogenic variant c.429T>A, p.(Tyr143*). Three other families each carried a different novel
variant. One had homozygous triplication of exons 8 and 9; another had homozygous deletion of exon 4; and another carried a novel c.419C>G variant encoding the missense p.Pro140Arg in
with c.1099-1G>A, a previously reported pathogenic splice variant. Expressing the missense heparanase-2 variant
showed that it was secreted as normal, suggesting that 140Arg has aberrant functionality after secretion. Bladder autonomic neurons emanate from pelvic ganglia where resident neural cell bodies derive from migrating neural crest cells. We demonstrated that, in normal human embryos, neuronal precursors near the developing hindgut and lower urinary tract were positive for both heparanase-2 and leucine rich repeats and immunoglobulin like domains 2 (LRIG2). Indeed, biallelic variants of
have been implicated in rare UFS families. The study expands the genotypic spectrum in
in UFS and supports a developmental neuronal pathobiology.
Background
Bazex–Dupré–Christol syndrome (BDCS; MIM301845) is a rare X‐linked dominant genodermatosis characterized by follicular atrophoderma, congenital hypotrichosis and multiple basal cell ...carcinomas (BCCs). Previous studies have linked BDCS to an 11·4‐Mb interval on chromosome Xq25‐q27.1. However, the genetic mechanism of BDCS remains an open question.
Objectives
To investigate the genetic aetiology and molecular mechanisms underlying BDCS.
Methods
We ascertained multiple individuals from eight unrelated families affected with BDCS (F1–F8). Whole‐exome (F1 and F2) and genome sequencing (F3) were performed to identify putative disease‐causing variants within the linkage region. Array comparative genomic hybridization and quantitative polymerase chain reaction (PCR) were used to explore copy number variations, followed by long‐range gap PCR and Sanger sequencing to amplify the duplication junctions and to define the head–tail junctions. Hi‐C was performed on dermal fibroblasts from two affected individuals with BDCS and one control. Public datasets and tools were used to identify regulatory elements and transcription factor binding sites within the minimal duplicated region. Immunofluorescence was performed in hair follicles, BCCs and trichoepitheliomas from patients with BDCS and sporadic BCCs. The ACTRT1 variant c.547dup (p.Met183Asnfs*17), previously proposed to cause BDCS, was evaluated with t allele frequency calculator.
Results
In eight families with BDCS, we identified overlapping 18–135‐kb duplications (six inherited and two de novo) at Xq26.1, flanked by ARHGAP36 and IGSF1. Hi‐C showed that the duplications did not affect the topologically associated domain, but may alter the interactions between flanking genes and putative enhancers located in the minimal duplicated region. We detected ARHGAP36 expression near the control hair follicular stem cell compartment, and found increased ARHGAP36 levels in hair follicles in telogen, in BCCs and in trichoepitheliomas from patients with BDCS. ARHGAP36 was also detected in sporadic BCCs from individuals without BDCS. Our modelling showed the predicted maximum tolerated minor allele frequency of ACTRT1 variants in control populations to be orders of magnitude higher than expected for a high‐penetrant ultra‐rare disorder, suggesting loss of function of ACTRT1 variants to be an unlikely cause for BDCS.
Conclusions
Noncoding Xq26.1 duplications cause BDCS. The BDCS duplications most likely lead to dysregulation of ARHGAP36. ARHGAP36 is a potential therapeutic target for both inherited and sporadic BCCs.
What is already known about this topic?
Bazex–Dupré–Christol syndrome (BDCS) is a rare X‐linked basal cell carcinoma susceptibility syndrome linked to an 11·4‐Mb interval on chromosome Xq25‐q27.1.
Loss‐of‐function variants in ACTRT1 and its regulatory elements were suggested to cause BDCS.
What does this study add?
BDCS is caused by small tandem noncoding intergenic duplications at chromosome Xq26.1.
The Xq26.1 BDCS duplications likely dysregulate ARHGAP36, the flanking centromeric gene.
ACTRT1 loss‐of‐function variants are unlikely to cause BDCS.
What is the translational message?
This study provides the basis for accurate genetic testing for BDCS, which will aid precise diagnosis and appropriate surveillance and clinical management.
ARHGAP36 may be a novel therapeutic target for all forms of sporadic basal cell carcinomas.
In this paper we show that Bazex‐Dupré‐Christol syndrome (BDCS), an X‐linked disorder of susceptibility to basal cell carcinomas, is caused by non‐coding Xq26.1 duplications that likely result in dysregulation of ARHGAP36, encoded by a flanking gene.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Myocardin (MYOCD) is the founding member of a class of transcriptional coactivators that bind the serum-response factor to activate gene expression programs critical in smooth muscle (SM) and cardiac ...muscle development. Insights into the molecular functions of MYOCD have been obtained from cell culture studies, and to date, knowledge about in vivo roles of MYOCD comes exclusively from experimental animals. Here, we defined an often lethal congenital human disease associated with inheritance of pathogenic MYOCD variants. This disease manifested as a massively dilated urinary bladder, or megabladder, with disrupted SM in its wall. We provided evidence that monoallelic loss-of-function variants in MYOCD caused congenital megabladder in males only, whereas biallelic variants were associated with disease in both sexes, with a phenotype additionally involving the cardiovascular system. These results were supported by cosegregation of MYOCD variants with the phenotype in 4 unrelated families by in vitro transactivation studies in which pathogenic variants resulted in abrogated SM gene expression and by the finding of megabladder in 2 distinct mouse models with reduced Myocd activity. In conclusion, we have demonstrated that variants in MYOCD result in human disease, and the collective findings highlight a vital role for MYOCD in mammalian organogenesis.
Does a genetic condition underlie the diagnosis of primary ovarian insufficiency (POI) in a 21-year-old woman with primary amenorrhoea?
A karyotype and genetic testing for Fragile X syndrome was ...undertaken. A next-generation sequencing panel of 24 genes associated with syndromal and non-syndromal POI was conducted.
A nonsense variant c.1336G>T, p.(Glu446Ter) and whole gene deletion in STAG3 were identified.
Biallelic loss of function variants in STAG3 are associated with primary ovarian failure type 8 and are a rare cause of POI.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The developmental disorder Burn‐McKeown Syndrome (BMKS) is characterised by choanal atresia and specific craniofacial features. BMKS is caused by biallelic variants in the pre‐messenger RNA splicing ...factor TXNL4A. Most patients have a loss‐of‐function variant in trans with a 34‐base pair (bp) deletion (type 1 Δ34) in the promoter region. Here, we identified two patients with BMKS. One individual has a TXNL4A c.93_94delCC, p.His32Argfs *21 variant combined with a type 1 Δ34 promoter deletion. The other has an intronic TXNL4A splice site variant (c.258‐3C>G) and a type 1 Δ34 promoter deletion. We show the c.258‐3C>G variant and a previously reported c.258‐2A>G variant, cause skipping of the final exon of TXNL4A in a minigene splicing assay. Furthermore, we identify putative transcription factor binding sites within the 56 bp of the TXNL4A promoter affected by the type 1 and type 2 Δ34 and use dual luciferase assays to identify a 22 bp repeated motif essential for TXNL4A expression within this promoter region. We propose that additional variants affecting critical transcription factor binding nucleotides within the 22 bp repeated motif could be relevant to BMKS aetiology. Finally, our data emphasises the need to analyse the non‐coding sequence in individuals where a single likely pathogenic coding variant is identified in an autosomal recessive disorder consistent with the clinical presentation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The bladder exstrophy–epispadias complex (BEEC) comprises of a spectrum of anterior midline defects, all affecting the lower urinary tract, the external genitalia, and the bony pelvis. In extreme ...cases, the gastrointestinal tract is also affected. The pathogenesis of BEEC is unclear but chromosomal aberrations have been reported. In particular, duplications of 22q11.2 have been identified in eight unrelated individuals with BEEC. The current study aimed to identify chromosomal copy number variants in BEEC. Analyses was performed using the Affymetrix Genome‐wide SNP6.0 assay in 92 unrelated patients cared for by two UK pediatric urology centers. Three individuals had a 22q11.2 duplication, a significantly higher number than that found in a control group of 12,500 individuals with developmental delay who had undergone microarray testing (p < .0001). Sequencing of CRKL, implicated in renal tract malformations in DiGeorge syndrome critical region at 22q11, in 89 individuals with BEEC lacking 22q11 duplications revealed no pathogenic variants. To date, 22q11.2 duplication is the genetic variant most commonly associated with BEEC. This is consistent with the hypothesis that altered expression of a single, yet to be defined, gene therein is critical to the pathogenesis of this potentially devastating congenital disorder.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Melkersson Rosenthal syndromes (MRS) is a rare autosomal dominantly inherited neurocutaneous syndrome characterised by a triad of facial (seventh cranial) nerve palsy, recurrent orofacial swelling ...and fissuring of the tongue. A recent report implicated a heterozygous missense variant in SLC27A1 (FATP1) as the cause of this condition in members of an affected Chinese family. We undertook Sanger sequencing of this gene in 14 affected unrelated individuals affected by MRS. We did not detect any putative pathogenic variants. Our data indicates that there is both clinical and genetic heterogeneity in this condition and that the causative gene remains to be identified for the majority of cases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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