RESUMEN
Genotype-phenotype correlations add value to the management of families with hereditary hearing loss (HL), where age-related typical audiograms (ARTAs) are generated from cross-sectional regression equations and used to predict the audiogram phenotype across the lifespan. A seven-generation kindred with autosomal dominant sensorineural HL (ADSNHL) was recruited and a novel pathogenic variant in POU4F3 (c.37del) was identified by combining linkage analysis with whole exome sequencing (WES). POU4F3 is noted for large intrafamilial variation including the age of onset of HL, audiogram configuration and presence of vestibular impairment. Sequential audiograms and longitudinal analyses reveal highly variable audiogram features among POU4F3 (c.37del) carriers, limiting the utility of ARTAs for clinical prognosis and management of HL. Furthermore, a comparison of ARTAs against three previously published families (1 Israeli Jewish, 2 Dutch) reveals significant interfamilial differences, with earlier onset and slower deterioration. This is the first published report of a North American family with ADSNHL due to POU4F3, the first report of the pathogenic c.37del variant, and the first study to conduct longitudinal analysis, extending the phenotypic spectrum of DFNA15.
Asunto(s)
Sordera , Pérdida Auditiva Sensorineural , Pérdida Auditiva , Humanos , Estudios Transversales , Proteínas de Homeodominio/genética , Pérdida Auditiva/genética , Pérdida Auditiva Sensorineural/diagnóstico , Pérdida Auditiva Sensorineural/genética , Pérdida Auditiva Sensorineural/patología , Linaje , Factor de Transcripción Brn-3C/genéticaRESUMEN
Otosclerosis is a bone disorder of the otic capsule and common form of late-onset hearing impairment. Considered a complex disease, little is known about its pathogenesis. Over the past 20 years, ten autosomal dominant loci (OTSC1-10) have been mapped but no genes identified. Herein, we map a new OTSC locus to a 9.96 Mb region within the FOX gene cluster on 16q24.1 and identify a 15 bp coding deletion in Forkhead Box L1 co-segregating with otosclerosis in a Caucasian family. Pre-operative phenotype ranges from moderate to severe hearing loss to profound sensorineural loss requiring a cochlear implant. Mutant FOXL1 is both transcribed and translated and correctly locates to the cell nucleus. However, the deletion of 5 residues in the C-terminus of mutant FOXL1 causes a complete loss of transcriptional activity due to loss of secondary (alpha helix) structure. FOXL1 (rs764026385) was identified in a second unrelated case on a shared background. We conclude that FOXL1 (rs764026385) is pathogenic and causes autosomal dominant otosclerosis and propose a key inhibitory role for wildtype Foxl1 in bone remodelling in the otic capsule. New insights into the molecular pathology of otosclerosis from this study provide molecular targets for non-invasive therapeutic interventions.
Asunto(s)
Otosclerosis , Factores de Transcripción Forkhead/genética , Humanos , Otosclerosis/genéticaRESUMEN
OBJECTIVES: Inappropriate antibiotic use contributes to antimicrobial resistance. The SpectrumTM app provides antibiotic decision support, based on local antimicrobial resistance rates. We determined the impact of regional implementation of the app on inpatient antimicrobial appropriateness, inpatient antimicrobial usage (AMU), population-based Clostridioides difficile infection (CDI) rates and cost, using a retrospective, before and after quasi-experimental design, including a one-year study period. METHODS: The SpectrumTM app was released to prescribers in February, 2019. We performed two one-day inpatient point prevalence surveys using the National Antimicrobial Prescribing Survey tool, six months before (June 25, 2018) and six months after (June 25, 2019) app dissemination. Inpatient AMU in Defined Daily Dose/1000 patient days and CDI incidence were compared, before and after app dissemination. RESULTS: The pre-survey included 184 prescriptions, and the post-survey included 197 prescriptions. Appropriateness was 97/176 (55.1%) pre, and 126/192 (65.6%) post (+10.5%, p = 0.051). Inpatient AMU declined by 6.6 DDD/1000 patient days per month, and CDI declined by 0.3 cases per month. Cost savings associated with reduced AMU were $403.98/bed/year and associated with reduced CDI were $82,078/year. CONCLUSION: We observed improvement in antimicrobial stewardship indicators following SpectrumTM implementation. We cannot determine the cause of these improvements.
Asunto(s)
Antibacterianos/uso terapéutico , Programas de Optimización del Uso de los Antimicrobianos/estadística & datos numéricos , Aplicaciones Móviles/estadística & datos numéricos , Canadá , Humanos , Prescripción Inadecuada/estadística & datos numéricos , Incidencia , Pacientes Internos/estadística & datos numéricos , Prevalencia , Estudios RetrospectivosRESUMEN
Stargardt disease (STGD1) is a form of inherited retinal dystrophy attributed to variants affecting function of the large ABCA4 gene and is arguably the most complex monogenic disease. Therapeutic trials in patients depend on identifying causal ABCA4 variants in trans, which is complicated by extreme allelic and clinical heterogeneity. We report the genetic architecture of STGD1 in the young genetically isolated population of Newfoundland, Canada. Population-based clinical recruitment over several decades yielded 29 STGD1 and STGD1-like families (15 multiplex, 14 singleton). Family interviews and public archival records reveal the vast majority of pedigree founders to be of English extraction. Full gene sequencing and haplotype analysis yielded a high solve rate (38/41 cases; 92.7%) for STGD1 and identified 16 causative STGD1 alleles, including a novel deletion (NM_000350.3: ABCA4 c.67-1delG). Several STGD1 alleles of European origin (including NM_000350.3: ABCA4 c.5714 + 5G>A and NM_000350.3: ABCA4 c.5461-10T>C) have drifted to a relatively high population frequency due to founder effect. We report on retinal disease progression in homozygous patients, providing valuable allele-specific insights. The least involved retinal disease is seen in patients homozygous for c.5714 + 5G>A variant, a so-called "mild" variant which is sufficient to precipitate a STGD1 phenotype in the absence of other pathogenic variants in the coding region and intron/exon boundaries of ABCA4. The most severe retinal disease is observed in cases with ABCA4 c.[5461-10T>C;5603A>T] complex allele. We discuss the advantages of determining genetic architecture in genetic isolates in order to begin to meet the grand challenge of human genetics.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/genética , Frecuencia de los Genes , Enfermedad de Stargardt/genética , Femenino , Efecto Fundador , Homocigoto , Humanos , Masculino , Mutación , LinajeRESUMEN
Genetic isolates provide unprecedented opportunities to identify pathogenic mutations and explore the full natural history of clinically heterogeneous phenotypes such as hearing loss. We noticed a unique audioprofile, characterized by prelingual and rapid deterioration of hearing thresholds at frequencies >0.5 kHz in several adults from unrelated families from the island population of Newfoundland. Targeted serial Sanger sequencing of probands for deafness alleles (n = 23) that we previously identified in this founder population was negative. Whole exome sequencing in four members of the largest family (R2010) identified a CLDN14 (DFNB29) variant [c.488C>T; p. (Ala163Val)], likely pathogenic, sensorineural hearing loss, autosomal recessive. Although not associated with deafness or disease, CLDN14 p.(Ala163Val) has been previously reported as a variant of uncertain significance (VUS). Targeted sequencing of 169 deafness probands identified one homozygote and one heterozygous carrier. Genealogical studies, cascade sequencing and haplotype analysis across four unrelated families showed all subjects with the unique audioprofile (n = 12) were also homozygous for p.(Ala163Val) and shared a 1.4 Mb DFNB29-associated haplotype on chromosome 21. Most significantly, sequencing 175 population controls revealed 1% of the population are heterozygous for CLDN14 p.(Ala163Val), consistent with a major founder effect in Newfoundland. The youngest CLDN14 [c.488C>T; p.(Ala163Val)] homozygote passed newborn screening and had normal hearing thresholds up to 3 years of age, which then deteriorated to a precipitous loss >1 kHz during the first decade. Our study suggests that genetic testing may be necessary to identify at-risk children in time to prevent speech, language and developmental delay.
Asunto(s)
Claudinas/genética , Efecto Fundador , Pérdida Auditiva Sensorineural/diagnóstico , Alelos , Secuencia de Aminoácidos , Niño , Preescolar , Claudinas/metabolismo , Sordera/diagnóstico , Sordera/genética , Femenino , Regulación de la Expresión Génica , Variación Genética , Estudio de Asociación del Genoma Completo , Haplotipos , Pérdida Auditiva Sensorineural/genética , Heterocigoto , Humanos , Masculino , Terranova y Labrador , Linaje , Análisis de Secuencia de ADNRESUMEN
PURPOSE: To describe the inheritance patterns and auditory phenotype features of 3 Canadian families with mutations in 2 X-linked "deafness" genes (DFNX). METHOD: Audiological, medical, and family histories were collected and family members interviewed to compare hearing thresholds and case histories between cases with mutations in SMPX versus POU3F4. RESULTS: The family pedigrees reveal characteristic X-linked inheritance patterns. Phenotypic features associated with the SMPX (DFNX4) mutation include early onset in males with rapid progression from mild and flat to sloping sensorineural loss, with highly variable onset and hearing loss severity in females. In contrast, phenotypic features associated with the POU3F4 (DFNX2) mutation are characterized by an early onset, mixed hearing loss with fluctuation in males, and a normal hearing phenotype reported for females. CONCLUSIONS: The study shows how this unique inheritance pattern and both gender and mutation-specific phenotype variations can alert audiologists to the presence of X-linked genetic etiologies in their clinical practice. By incorporating this knowledge into clinical decision making, audiologists can facilitate the early identification of X-linked hearing loss and contribute to the effective team management of affected families.
Asunto(s)
Enfermedades Genéticas Ligadas al Cromosoma X/genética , Pérdida Auditiva Conductiva/genética , Pérdida Auditiva Sensorineural/genética , Proteínas Musculares/genética , Factores del Dominio POU/genética , Edad de Inicio , Audiometría de Tonos Puros , Umbral Auditivo , Preescolar , Deleción Cromosómica , Codón sin Sentido/genética , Diagnóstico Diferencial , Exones/genética , Femenino , Tamización de Portadores Genéticos , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico , Pérdida Auditiva Conductiva/diagnóstico , Perdida Auditiva Conductiva-Sensorineural Mixta/diagnóstico , Perdida Auditiva Conductiva-Sensorineural Mixta/genética , Perdida Auditiva Conductiva-Sensorineural Mixta/terapia , Pérdida Auditiva Sensorineural/diagnóstico , Pérdida Auditiva Sensorineural/terapia , Humanos , Estudios Longitudinales , Masculino , Linaje , Fenotipo , Mutación Puntual/genética , Estudios Retrospectivos , Factores SexualesRESUMEN
X-linked hearing loss is the rarest form of genetic hearing loss contributing to <1% of cases. We identified a multiplex family from Newfoundland (Family 2024) segregating X-linked hearing loss. Haplotyping of the X chromosome and sequencing of positional candidate genes revealed a novel point deletion (c.99delC) in SMPX which encodes a small muscle protein responsible for reducing mechanical stress during muscle contraction. This novel deletion causes a frameshift and a premature stop codon (p.Arg34GlufsX47). We successfully sequenced both SMPX wild-type and mutant alleles from cDNA of a lymphoblastoid cell line, suggesting that the mutant allele may not be degraded via nonsense-mediated mRNA decay. To investigate the role of SMPX in other subpopulations, we fully sequenced SMPX in 229 Canadian probands with hearing loss and identified a second Newfoundland Family (2196) with the same mutation, and a shared haplotype on the X chromosome, suggesting a common ancestor.