Extended phenotypes of PIEZO1-related lymphatic dysplasia caused by two novel compound heterozygous variants

Spinal scoliosis: insights into developmental mechanisms and animal models

Spinal scoliosis, a prevalent spinal deformity impacting both physical and mental well-being, has a significant genetic component, though the exact pathogenic mechanisms remain elusive. This review offers a comprehensive exploration of current research on embryonic spinal development, focusing on the genetic and biological intricacies governing axial elongation and straightening. Zebrafish, a vital model in developmental biology, takes a prominent role in understanding spinal scoliosis. Insights from zebrafish studies illustrate genetic and physiological aspects, including notochord development and cerebrospinal fluid dynamics, revealing the anomalies contributing to scoliosis. In this review, we acknowledge existing challenges, such as deciphering the unique dynamics of human spinal development, variations in physiological curvature, and disparities in cerebrospinal fluid circulation. Further, we emphasize the need for caution when extrapolating findings to humans and for future research to bridge current knowledge gaps. We hope that this review will be a beneficial frame of reference for the guidance of future studies on animal models and genetic research for spinal scoliosis.

The role of mechanically sensitive ion channel Piezo1 in bone remodeling

Piezo1 (2010) was identified as a mechanically activated cation channel capable of sensing various physical forces, such as tension, osmotic pressure, and shear force. Piezo1 mediates mechanosensory transduction in different organs and tissues, including its role in maintaining bone homeostasis. This review aimed to summarize the function and possible mechanism of Piezo1 in the mechanical receptor cells in bone tissue. We found that it is a potential therapeutic target for the treatment of bone diseases.

Piezo1 mutant zebrafish as a model of idiopathic scoliosis

Scoliosis is a condition where the spine curves sideways, unique to humans due to their upright posture. However, the cause of this disease is not well understood because it is challenging to find a model for experimentation. This study aimed to create a model for human idiopathic scoliosis by manipulating the function of mechanosensitive channels called Piezo channels in zebrafish. Zebrafish were chosen because they experience similar biomechanical forces to humans, particularly in relation to the role of mechanical force in scoliosis progression. Here we describe piezo1 and piezo2a are involved in bone formation, with a double knockout resulting in congenital systemic malformations. However, an in-frame mutation of piezo1 led to fully penetrant juvenile-onset scoliosis, bone asymmetry, reduced tissue mineral density, and abnormal intervertebral discs-resembling non-congenital scoliosis symptoms in humans. These findings suggest that functional Piezo channels responding to mechanical forces are crucial for bone formation and maintaining spine integrity, providing insights into skeletal disorders.

Perinatal presentations of non-immune hydrops fetalis due to recessive PIEZO1 disease: A challenging fetal diagnosis

Hydrops fetalis is a rare disorder associated with significant perinatal complications and a high perinatal mortality of at least 50%. Nonimmune hydrops fetalis (NIHF) is more frequent and results from a wide variety of etiologies. One cause of NIHF is lymphatic malformation 6 (LMPHM6) due to biallelic loss-of-function (LoF) variants in PIEZO1. Most individuals are diagnosed postnatally and only few clinical data are available on fetal presentations. We report six novel biallelic predicted LoF variants in PIEZO1 identified by exome sequencing in six fetuses and one deceased neonate from four unrelated families affected with LMPHM6. During the pregnancy, most cases are revealed by isolated NIHF at second trimester of gestation. At post-mortem examination ascites, pleural effusions and telengectasies can guide the etiological diagnosis. We aim to further describe the perinatal presentation of this condition which could be underdiagnosed.

The Korean undiagnosed diseases program phase I: expansion of the nationwide network and the development of long-term infrastructure

BACKGROUND

Phase I of the Korean Undiagnosed Diseases Program (KUDP), performed for 3 years, has been completed. The Phase I program aimed to solve the problem of undiagnosed patients throughout the country and develop infrastructure, including a data management system and functional core laboratory, for long-term translational research. Herein, we share the clinical experiences of the Phase I program and introduce the activities of the functional core laboratory and data management system.

RESULTS

During the program (2018-2020), 458 patients were enrolled and classified into 3 groups according to the following criteria: (I) those with a specific clinical assessment which can be verified by direct testing (32 patients); (II) those with a disease group with genetic and phenotypic heterogeneity (353 patients); and (III) those with atypical presentations or diseases unknown to date (73 patients). All patients underwent individualized diagnostic processes based on the decision of an expert consortium. Confirmative diagnoses were obtained for 242 patients (52.8%). The diagnostic yield was different for each group: 81.3% for Group I, 53.3% for Group II, and 38.4% for Group III. Diagnoses were made by next-generation sequencing for 204 patients (84.3%) and other genetic testing for 35 patients (14.5%). Three patients (1.2%) were diagnosed with nongenetic disorders. The KUDP functional core laboratory, with a group of experts, organized a streamlined research pipeline covering various resources, including animal models, stem cells, structural modeling and metabolic and biochemical approaches. Regular data review was performed to screen for candidate genes among undiagnosed patients, and six different genes were identified for functional research. We also developed a web-based database system that supports clinical cohort management and provides a matchmaker exchange protocol based on a matchbox, likely to reinforce the nationwide clinical network and further international collaboration.

CONCLUSIONS

The KUDP evaluated the unmet needs of undiagnosed patients and established infrastructure for a data-sharing system and future functional research. The advancement of the KUDP may lead to sustainable bench-to-bedside research in Korea and contribute to ongoing international collaboration.

Non-immune hydrops fetalis caused by PIEZO1 compound heterozygous deletions detected only by exome sequencing

This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Identification of Genetic Risk Factors of Severe COVID-19 Using Extensive Phenotypic Data: A Proof-of-Concept Study in a Cohort of Russian Patients

The COVID-19 pandemic has drawn the attention of many researchers to the interaction between pathogen and host genomes. Over the last two years, numerous studies have been conducted to identify the genetic risk factors that predict COVID-19 severity and outcome. However, such an analysis might be complicated in cohorts of limited size and/or in case of limited breadth of genome coverage. In this work, we tried to circumvent these challenges by searching for candidate genes and genetic variants associated with a variety of quantitative and binary traits in a cohort of 840 COVID-19 patients from Russia. While we found no gene- or pathway-level associations with the disease severity and outcome, we discovered eleven independent candidate loci associated with quantitative traits in COVID-19 patients. Out of these, the most significant associations correspond to rs1651553 in MYH14p = 1.4 × 10^-7), rs11243705 in SETX (p = 8.2 × 10^-6), and rs16885 in ATXN1 (p = 1.3 × 10^-5). One of the identified variants, rs33985936 in SCN11A, was successfully replicated in an independent study, and three of the variants were found to be associated with blood-related quantitative traits according to the UK Biobank data (rs33985936 in SCN11A, rs16885 in ATXN1, and rs4747194 in CDH23). Moreover, we show that a risk score based on these variants can predict the severity and outcome of hospitalization in our cohort of patients. Given these findings, we believe that our work may serve as proof-of-concept study demonstrating the utility of quantitative traits and extensive phenotyping for identification of genetic risk factors of severe COVID-19.