The Importance of Newborn Genetic Screening for Early Identification of GJB2 and SLC26A4 Related Hearing Loss.

Objective: To assess the added benefit of newborn genetic screening for GJB2 and SLC26A4 variants in conjunction with newborn hearing screening.

Study Design: Retrospective cohort study.

Methods: Children with known variants of GJB2 and SLC26A4 were identified from 485 children with hearing loss who underwent testing with Next Generation Sequencing (NGS) between January 2015 and February 2018, prior to expanded screening for genetic variants and congenital CMV.

Exome Sequencing in the Diagnostic Pathway for Suspected Rare Genetic Diseases: Does the Order of Testing Affect its Cost-Effectiveness?

Background: Patients with suspected rare diseases often experience lengthy and uncertain diagnostic pathways. This study aimed to estimate the cost-effectiveness of exome sequencing (ES) in different positions in the diagnostic pathway for patients suspected of having a rare genetic disease.

Methods: Data collected retrospectively from 305 patients suspected of having a rare genetic disease (RGD), who received clinical-grade ES and participated in the Canadian multicentre Care4Rare-SOLVE study, informed a discrete event simulation of the diagnostic pathway.

Epigenomic and phenotypic characterization of DEGCAGS syndrome.

Developmental Delay with Gastrointestinal, Cardiovascular, Genitourinary, and Skeletal Abnormalities syndrome (DEGCAGS, MIM #619488) is caused by biallelic, loss-of-function (LoF) ZNF699 variants, and is characterized by variable neurodevelopmental disability, discordant organ anomalies among full siblings and infant mortality. ZNF699 encodes a KRAB zinc finger protein of unknown function. We aimed to investigate the genotype-phenotype spectrum of DEGCAGS and the possibility of a diagnostic DNA methylation episignature, to facilitate the diagnosis of a highly variable condition lacking pathognomonic clinical findings.

Fracture prevalence in children diagnosed with Ehlers-Danlos Syndrome and Generalized Joint Hypermobility.

Background: There is limited understanding of the hypothesized association between the Ehlers-Danlos Syndromes (EDS), hypermobility and fractures in children. Despite this, EDS and hypermobility continue to be raised in the legal setting as possible causes of unexplained fractures in infants where there is a concern for physical abuse. Further understanding is needed regarding fractures in children with EDS and hypermobility.

Expanded phenotypic spectrum of neurodevelopmental and neurodegenerative disorder Bryant-Li-Bhoj syndrome with 38 additional individuals.

Bryant-Li-Bhoj syndrome (BLBS), which became OMIM-classified in 2022 (OMIM: 619720, 619721), is caused by germline variants in the two genes that encode histone H3.3 (H3-3A/H3F3A and H3-3B/H3F3B) [1-4]. This syndrome is characterized by developmental delay/intellectual disability, craniofacial anomalies, hyper/hypotonia, and abnormal neuroimaging [1, 5].

A systematic assessment of the impact of rare canonical splice site variants on splicing using functional and in silico methods.

Canonical splice site variants (CSSVs) are often presumed to cause loss-of-function (LoF) and are assigned very strong evidence of pathogenicity (according to American College of Medical Genetics/Association for Molecular Pathology criterion PVS1). The exact nature and predictability of splicing effects of unselected rare CSSVs in blood-expressed genes are poorly understood. We identified 168 rare CSSVs in blood-expressed genes in 112 individuals using genome sequencing, and studied their impact on splicing using RNA sequencing (RNA-seq).

Variants in Genes Associated with Hearing Loss in Children: Prevalence in a Large Canadian Cohort.

Objective: The objective of this study was to assess the prevalence of genetic variants associated with hearing loss in a large cohort of children in Canada using high throughput next generation sequencing (NGS).

Methods: A total of 485 children with hearing loss underwent NGS testing with an 80 gene panel of syndromic and non-syndromic variants known to be associated with hearing loss. Genetic variants were classified as pathogenic, likely pathogenic, likely benign, benign, or variants of uncertain significance (VUS), according to the American College of Medical Genetics and Genomics guidelines.

Cellular Modeling of CLN6 with IPSC-derived Neurons and Glia.

Neuronal ceroid lipofuscinosis (NCL), type 6 (CLN6) is a neurodegenerative disorder associated with progressive neurodegeneration leading to dementia, seizures, and retinopathy. encodes a resident-ER protein involved in trafficking lysosomal proteins to the Golgi. CLN6p deficiency results in lysosomal dysfunction and deposition of storage material comprised of Nile Red lipids/proteolipids that include subunit C of the mitochondrial ATP synthase (SUBC).

Evaluation of the diagnostic accuracy of exome sequencing and its impact on diagnostic thinking for patients with rare disease in a publicly funded health care system: A prospective cohort study.

Purpose: To evaluate the diagnostic utility of publicly funded clinical exome sequencing (ES) for patients with suspected rare genetic diseases.

Methods: We prospectively enrolled 297 probands who met eligibility criteria and received ES across 5 sites in Ontario, Canada, and extracted data from medical records and clinician surveys. Using the Fryback and Thornbury Efficacy Framework, we assessed diagnostic accuracy by examining laboratory interpretation of results and assessed diagnostic thinking by examining the clinical interpretation of results and whether clinical-molecular diagnoses would have been achieved via alternative hypothetical molecular tests.

Heterozygous nonsense variants in the ferritin heavy-chain gene FTH1 cause a neuroferritinopathy.

Ferritin, the iron-storage protein, is composed of light- and heavy-chain subunits, encoded by FTL and FTH1, respectively. Heterozygous variants in FTL cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in FTH1 have not been previously associated with neurologic disease.

Protocol for a Prospective, Observational Cost-effectiveness Analysis of Returning Secondary Findings of Genome Sequencing for Unexplained Suspected Genetic Conditions.

Purpose: Although costly, genome-wide sequencing (GWS) detects an extensive range of variants, enhancing our ability to diagnose and assess risk for an increasing number of diseases. In addition to detecting variants related to the indication for testing, GWS can detect secondary variants in BRCA1, BRCA2, and other genes for which early intervention may improve health. As the list of secondary findings grows, there is increased demand for surveillance and management by multiple specialists, adding pressure to constrained health care budgets.

Null and missense mutations of ERI1 cause a recessive phenotypic dichotomy in humans.

ERI1 is a 3'-to-5' exoribonuclease involved in RNA metabolic pathways including 5.8S rRNA processing and turnover of histone mRNAs. Its biological and medical significance remain unclear.

Monoallelic loss-of-function BMP2 variants result in BMP2-related skeletal dysplasia spectrum.

Purpose: Bone morphogenic proteins (BMPs) regulate gene expression that is related to many critical developmental processes, including osteogenesis for which they are named. In addition, BMP2 is widely expressed in cells of mesenchymal origin, including bone, cartilage, skeletal and cardiac muscle, and adipose tissue. It also participates in neurodevelopment by inducing differentiation of neural stem cells.

Trio RNA sequencing in a cohort of medically complex children.

Genome sequencing (GS) is a powerful test for the diagnosis of rare genetic disorders. Although GS can enumerate most non-coding variation, determining which non-coding variants are disease-causing is challenging. RNA sequencing (RNA-seq) has emerged as an important tool to help address this issue, but its diagnostic utility remains understudied, and the added value of a trio design is unknown.

Heterozygous Nonsense Variants in the Ferritin Heavy Chain Gene Cause a Novel Pediatric Neuroferritinopathy.

Ferritin, the iron storage protein, is composed of light and heavy chain subunits, encoded by and , respectively. Heterozygous variants in cause hereditary neuroferritinopathy, a type of neurodegeneration with brain iron accumulation (NBIA). Variants in have not been previously associated with neurologic disease.

Early diagnosis of ichthyosis, leukocyte vacuoles, alopecia, and sclerosing cholangitis syndrome: A case report.

Congenital ichthyosis is a genodermatosis characterized by abnormal epidermal differentiation. The neonatal period is critical for patients with ichthyosis because of the risk for significant comorbidities and associated mortality, with most complications resulting from impaired barrier function. Early recognition can significantly alter the clinical course of this rare disease.

Bridging clinical care and research in Ontario, Canada: Maximizing diagnoses from reanalysis of clinical exome sequencing data.

We examined the utility of clinical and research processes in the reanalysis of publicly-funded clinical exome sequencing data in Ontario, Canada. In partnership with eight sites, we recruited 287 families with suspected rare genetic diseases tested between 2014 and 2020. Data from seven laboratories was reanalyzed with the referring clinicians.