Monogenic diseases in respiratory medicine: Clinical perspectives

Clinical outcomes following preimplantation genetic testing for monogenic conditions: a systematic review of observational studies

OBJECTIVE

We aimed to report a summary of clinical outcomes following preimplantation genetic testing for monogenic conditions, by performing a systematic review of published literature on clinical pregnancy and live birth rates following preimplantation genetic testing due to a monogenic indication. Additionally, we aimed to undertake a subgroup analysis of clinical outcomes of concurrent monogenic and aneuploidy screening.

DATA SOURCES

Three electronic databases (MEDLINE, EMBASE, and PubMed) were searched from inception to May 2024.

STUDY ELIGIBILITY CRITERIA

Quantitative data audits, observational studies, and case series reporting clinical outcomes for individuals undergoing preimplantation genetic testing for a monogenic indication were included. Only studies using blastocyst biopsies with polymerase chain reaction-based or genome-wide haplotyping methods for molecular analysis were eligible to reflect current laboratory practice.

METHODS

Quality assessment was performed following data extraction using an adaptation of the Joanna Briggs critical appraisal tool for case series. Results were extracted, and pooled mean clinical pregnancy rates and birth rates were calculated with 95% confidence intervals (95% CI). We compared outcomes between those with and without concurrent preimplantation genetic testing for aneuploidy.

RESULTS

Our search identified 1372 publications; 51 were eligible for inclusion. Pooled data on 5305 cycles and 5229 embryo transfers yielded 1806 clinical pregnancies and 1577 births. This translated to clinical pregnancy and birth rates of 34.0% [95% CI: 32.8%-35.3%] and 29.7% [95% CI: 28.5%-31.0%] per cycle and 24.8% [95% CI: 23.6%-26.0%] and 21.7% [95% CI: 20.8%-23.1%] per embryo transfer. In studies with concurrent aneuploidy screening, clinical pregnancy and birth rates were 43.3% [95% CI: 40.2%-46.5%] and 37.6% [95% CI: 34.6%-40.8%] per cycle and 37.0% [95% CI: 33.9%-40.3%] and 31.8% [95% CI: 28.8%-35.0%] per embryo transfer. Studies without aneuploidy screening reported clinical pregnancy and birth rates of 32.5% [95% CI: 31.0%-34.1%] and 28.1% [95% CI: 26.6%-29.7%] per cycle and 21.2% [95% CI: 19.8%-22.6%] and 18.6% [95% CI: 17.3%-20.0%] per embryo transfer.

CONCLUSION

This systematic review reveals promising clinical outcome figures for this indication group. Additionally, synthesizing the published scientific literature on clinical outcomes from preimplantation genetic testing for monogenic conditions provides a rigorous, noncommercial evidence base for counseling.

Plasmid Gene Therapy for Monogenic Disorders: Challenges and Perspectives

Monogenic disorders are a group of human diseases caused by mutations in single genes. While some disease-altering treatments offer relief and slow the progression of certain conditions, the majority of monogenic disorders still lack effective therapies. In recent years, gene therapy has appeared as a promising approach for addressing genetic disorders. However, despite advancements in gene manipulation tools and delivery systems, several challenges remain unresolved, including inefficient delivery, lack of sustained expression, immunogenicity, toxicity, capacity limitations, genomic integration risks, and limited tissue specificity. This review provides an overview of the plasmid-based gene therapy techniques and delivery methods currently employed for monogenic diseases, highlighting the challenges they face and exploring potential strategies to overcome these barriers.

Impact of prenatal genomics on clinical genetics practice

Genetic testing for prenatal diagnosis in the pre-genomic era primarily focused on detecting common fetal aneuploidies, using methods that combine maternal factors and imaging findings. The genomic era, ushered in by the emergence of new technologies like chromosomal microarray analysis and next-generation sequencing, has transformed prenatal diagnosis. These new tools enable screening and testing for a broad spectrum of genetic conditions, from chromosomal to monogenic disorders, and significantly enhance diagnostic precision and efficacy. This chapter reviews the transition from traditional karyotyping to comprehensive sequencing-based genomic analyses. We discuss both the clinical utility and the challenges of integrating prenatal exome and genome sequencing into prenatal care and underscore the need for ethical frameworks, improved prenatal phenotypic characterization, and global collaboration to further advance the field.

Exome sequencing as the first-tier test for pediatric respiratory diseases: A single-center study

The high clinical and genetic heterogeneity makes it difficult to reach a confirmative diagnosis of suspected pediatric respiratory inherited diseases. Many patients with monogenic respiratory disorders could be missed without genetic testing. We performed a single-center study in Beijing Children's Hospital to demonstrate the clinical utility of exome sequencing (ES) as a first-tier test by evaluating the diagnostic yields of ES for inherited diseases with respiratory symptoms. A total of 107 patients were recruited in this study. We identified 51 pathogenic or likely pathogenic variants in 37 patients by ES (with or without copy number variants sequencing). The overall diagnostic yield was 34.6% (37/107). The most frequent disorders in our cohort were primary immunodeficiency disease (PIDs) (18/37, 48.6%) and primary ciliary dyskinesia (PCD) (9/37, 24.3%). We further reviewed the directive outcomes of genetic testing on the 37 positive cases. Our study demonstrated the effectiveness of ES as a first-tier test in China for diagnosing monogenic diseases of the respiratory system. In the era of precision medicine, ES as a first-tier test can rapidly make a molecular diagnosis and direct the intervention of the positive cases in pediatric respiratory medicine.

Will Airway Gene Therapy for Cystic Fibrosis Improve Lung Function? New Imaging Technologies Can Help Us Find Out

The promise of genetic therapies has turned into reality in recent years, with new first-line treatments for fatal diseases now available to patients. The development and testing of genetic therapies for respiratory diseases such as cystic fibrosis (CF) has also progressed. The addition of gene editing to the genetic agent toolbox, and its early success in other organ systems, suggests we will see rapid expansion of gene correction options for CF in the future. Although substantial progress has been made in creating techniques and genetic agents that can be highly effective for CF correction in vitro, physiologically relevant functional in vivo changes have been largely prevented by poor delivery efficiency within the lungs. Somewhat hidden from view, however, is the absence of reliable, accurate, detailed, and noninvasive outcome measures that can detect subtle disease and treatment effects in the lungs of humans or animal models. The ability to measure the fundamental function of the lung-ventilation, the effective transport of air throughout the lung-has been constrained by the available measurement technologies. Without sensitive measurement methods, it is difficult to quantify the effectiveness of genetic therapies for CF. The mainstays of lung health assessment are spirometry, which cannot provide adequate disease localization and is not sensitive enough to detect small early changes in disease; and computed tomography, which provides structural rather than functional information. Magnetic resonance imaging using hyperpolarized gases is increasingly useful for lung ventilation assessment, and it removes the radiation risk that accompanies X-ray methods. A new lung imaging technique, X-ray velocimetry, can now offer highly detailed regional lung ventilation information well suited to the diagnosis, treatment, and monitoring needs of CF lung disease, particularly after the application of genetic therapies. In this review, we discuss the options now available for imaging-based lung function measurement in the generation and use of genetic and other therapies for treating CF lung disease.