Genetic Diagnosis, Screening, and Laboratory Testing

Cerebral Publication Private Limited | CIN: U58111DL2025PTC459104 | 2026 | Volume 1 | Issue 2 | Page 1-300 | ISBN: 978-81-689463-0-9 | Book Title: - Textbook of Clinical Genetics | Chapter-7: Genetic Diagnosis, Screening, and Laboratory Testing

Abstract

Genetic diagnosis, screening, and laboratory testing are integral components of modern clinical genetics, enabling the early detection, accurate diagnosis, and effective management of inherited and acquired genetic disorders. Advances in molecular biology, cytogenetics, and genomic technologies have transformed diagnostic capabilities, allowing healthcare professionals to identify disease-causing genetic variants with unprecedented precision. These approaches support clinical decision-making across a wide range of medical specialties, including prenatal medicine, pediatrics, oncology, reproductive health, neurology, cardiology, and rare disease management. Early genetic diagnosis facilitates timely intervention, personalized treatment, and improved patient outcomes while reducing the burden of preventable genetic diseases.

This chapter provides an overview of the principles and methodologies of genetic testing, including cytogenetic analysis, polymerase chain reaction (PCR), Sanger sequencing, next-generation sequencing (NGS), whole-exome sequencing (WES), whole-genome sequencing (WGS), chromosomal microarray analysis (CMA), fluorescence in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), and quantitative PCR. It also discusses the clinical applications of carrier screening, newborn screening, prenatal screening, preimplantation genetic testing (PGT), predictive and presymptomatic testing, pharmacogenomic testing, and population-based genetic screening programs. Emphasis is placed on laboratory quality assurance, test validation, variant interpretation based on international guidelines, and multidisciplinary collaboration for accurate diagnosis.

The chapter further examines ethical, legal, and social issues related to genetic testing, including informed consent, confidentiality, incidental findings, genetic discrimination, and the importance of comprehensive genetic counseling before and after testing. Emerging technologies such as long-read sequencing, liquid biopsy, digital PCR, multi-omics integration, and artificial intelligence-assisted genomic interpretation are also highlighted for their expanding role in precision medicine.

A thorough understanding of genetic diagnosis, screening, and laboratory testing equips healthcare professionals, laboratory scientists, researchers, and students with the knowledge required to integrate genomic information into routine clinical practice, improve diagnostic accuracy, support personalized healthcare, and advance preventive and precision medicine for diverse patient populations.