Mucins are large, highly glycosylated extracellular matrix proteins that line and protect epithelia of the respiratory, digestive, and urogenital tracts. Previous work has shown that mucins form ...large, interconnected polymeric networks that mediate their biological functions once secreted. However, how these large matrix molecules are compacted and packaged into much smaller secretory granules within cells prior to secretion is largely unknown. Here, we demonstrate that a small cysteine-rich adaptor protein is essential for proper packaging of a secretory mucin in vivo. This adaptor acts via cysteine bonding between itself and the cysteine-rich domain of the mucin. Loss of this adaptor protein disrupts mucin packaging in secretory granules, alters the mobile fraction within granules, and results in granules that are larger, more circular, and more fragile. Understanding the factors and mechanisms by which mucins and other highly glycosylated matrix proteins are properly packaged and secreted may provide insight into diseases characterized by aberrant mucin secretion.
Abstract Exome sequencing (ES) has emerged as an essential tool in the evaluation of neurodevelopmental disorders (NDD) of unknown etiology. Genome sequencing (GS) offers advantages over ES due to ...improved detection of structural, copy number, repeat number and non‐coding variants. However, GS is less commonly utilized due to higher cost and more intense analysis. Here, we present nine cases of pediatric NDD that were molecularly diagnosed with GS between 2017 and 2022, following non‐diagnostic ES. All individuals presented with global developmental delay or regression. Other features present in our cohort included epilepsy, white matter abnormalities, brain malformation and dysmorphic features. Two cases were diagnosed on GS due to newly described gene‐disease relationship or variant reclassification ( MAPK8IP3, CHD3 ). Additional features missed on ES that were later detected on GS were: intermediate‐size deletions in three cases who underwent ES that were not validated for CNV detection, pathogenic variants within the non‐protein coding genes SNORD118 and RNU7‐1 , pathogenic variant within the promoter region of GJB1 , and a coding pathogenic variant within BCAP31 which was not sufficiently covered on ES. GS following non‐diagnostic ES led to the identification of pathogenic variants in this cohort of nine cases, four of which would not have been identified by reanalysis alone.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Undiagnosed genetic disease imposes a significant burden on families and health-care resources, especially in cases with a complex phenotype. Here we present a child with suspected leukodystrophy in ...the context of additional features, including hearing loss, clinodactyly, rotated thumbs, tapered fingers, and simplified palmar crease. Trio genome sequencing (GS) identified three molecular diagnoses in this individual: compound heterozygous missense variants associated with polymerase III (Pol III)-related leukodystrophy, a 4-Mb de novo copy-number loss including the
gene associated with Feingold syndrome, and a mosaic single-nucleotide variant associated with
-related disorders. These variants fully account for the individual's features, but also illustrate the potential for superimposed and unclear contributions of multiple diagnoses to an individual's overall presentation. This report demonstrates the advantage of GS in detection of multiple variant types, including low-level mosaic variants, and emphasizes the need for comprehensive genetic analysis and detailed clinical phenotyping to provide individuals and their families with the maximum benefit for clinical care and genetic counseling.
There is mounting evidence of the value of clinical genome sequencing (cGS) in individuals with suspected rare genetic disease (RGD), but cGS performance and impact on clinical care in a diverse ...population drawn from both high-income countries (HICs) and low- and middle-income countries (LMICs) has not been investigated. The iHope program, a philanthropic cGS initiative, established a network of 24 clinical sites in eight countries through which it provided cGS to individuals with signs or symptoms of an RGD and constrained access to molecular testing. A total of 1,004 individuals (median age, 6.5 years; 53.5% male) with diverse ancestral backgrounds (51.8% non-majority European) were assessed from June 2016 to September 2021. The diagnostic yield of cGS was 41.4% (416/1,004), with individuals from LMIC sites 1.7 times more likely to receive a positive test result compared to HIC sites (LMIC 56.5% 195/345 vs. HIC 33.5% 221/659, OR 2.6, 95% CI 1.9–3.4, p < 0.0001). A change in diagnostic evaluation occurred in 76.9% (514/668) of individuals. Change of management, inclusive of specialty referrals, imaging and testing, therapeutic interventions, and palliative care, was reported in 41.4% (285/694) of individuals, which increased to 69.2% (480/694) when genetic counseling and avoidance of additional testing were also included. Individuals from LMIC sites were as likely as their HIC counterparts to experience a change in diagnostic evaluation (OR 6.1, 95% CI 1.1–∞, p = 0.05) and change of management (OR 0.9, 95% CI 0.5–1.3, p = 0.49). Increased access to genomic testing may support diagnostic equity and the reduction of global health care disparities.
iHope provided clinical genome testing to a global population of 1,004 underserved individuals with suspected rare genetic disease. Diagnostic yield, and the proportion with a change of management, was >40% for individuals from both low- and middle-income or high-income countries, suggesting that widespread availability of genomic testing may reduce health disparities.
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