WMO Education and Training Programme

Whole Genome Sequencing for Rare Diseases

The diagnosis and treatment of rare diseases have long been a daunting challenge due to their complex and often undefined nature. However, with recent advancements in technology, specifically in the realm of genomics, whole genome sequencing (WGS) has emerged as a powerful tool that has revolutionized the diagnosis and management of rare diseases. This groundbreaking technique offers hope to countless individuals and their families who have suffered from the uncertainties and lack of answers associated with these conditions.

What are rare diseases?

Rare diseases are a diverse group of disorders that affect a small percentage of the population, often occurring as a result of genetic mutations. With over 7,000 rare diseases identified worldwide, their rarity makes them particularly challenging to diagnose accurately. Traditional diagnostic methods often involve time-consuming and costly procedures, such as multiple invasive tests, leading to delayed or missed diagnoses. Advances in genetic sequencing in molecular diagnostic techniques have greatly improved scientists' ability to understand rare diseases.

 Whole genome sequencing for rare diseases

Whole genome sequencing, or the comprehensive analysis of an individual's complete set of genes, has emerged as a game-changer in diagnosing rare diseases. WGS allows the analysis of unknown etiological variants in the coding and noncoding regions of rare disease genomes, and the use of WGS can play a synergistic role in diagnosis and etiological discovery in routine healthcare. The application of existing WGS technologies to rare disease cases has proven to be useful in identifying the cause of disease by detecting multiple and comprehensive mutations at the whole-genome level, providing invaluable insights into the underlying molecular mechanisms of various rare diseases and opening up new possibilities for personalized medicine.

Whole genome sequencing offers several advantages over traditional genetic testing methods. For starters, it allows researchers and scientists to examine not just a handful, but all of an individual's genes. This comprehensive analysis helps in identifying rare genetic variations that might have been missed by targeted genetic tests. Moreover, by analyzing the entire genome, researchers can study the interactions between different genes and understand how different mutations work together to cause a disease.

The power of whole genome sequencing lies in its ability to provide precise and accurate diagnoses. In some cases, these diagnoses can even lead to the development of targeted therapies tailored specifically to the individual's unique genetic makeup.

Beyond diagnosis, whole genome sequencing also plays a crucial role in advancing the understanding of rare diseases. By studying the genetic variations found in patients, researchers can gain insights into the underlying biological processes and pathways involved in these diseases. This knowledge not only helps in developing novel treatment strategies but can also aid in identifying potential biomarkers for early detection or monitoring disease progression.

Key whole genome sequencing methods

The key whole-genome sequencing methods include human whole-genome sequencing and Phased sequencing. Human whole-genome sequencing offers the most detailed view of the human genetic code and valuable information for the study of rare diseases and phased sequencing distinguishes between alleles on homologous chromosomes to produce genome-wide haplotypes, which are often important for the study of genetically rare diseases.

With these whole genome sequencing methods, researchers can achieve:

l Identification of structural variants in rare disease research, including deletions, insertions, inversions, duplications, copy-number variants, and translocations.

l Detection of small variants in challenging regions of the genome.

l Capture the full length and sequence of repeat expansions.

l Phasing rare disease variants across alleles.

In conclusion, WGS provides great convenience for research and diagnosis of genetic rare diseases.