Whole Genome Sequencing (WGS)

Introduction

Whole Genome Sequencing (WGS) is a technique used to determine the complete DNA sequence of an organism’s genome at a single time. It provides a comprehensive view of the entire genetic material, including coding and non-coding regions.

Steps in Whole Genome Sequencing

1 DNA Extraction – Isolate high-quality DNA from cells or tissues.
2 Library Preparation – Fragment DNA and attach sequencing adapters.
3 Sequencing – Use platforms like Illumina, PacBio, or Oxford Nanopore to read DNA sequences.
4 Data Analysis – Align sequences to a reference genome and identify genetic variations.
5 Variant Calling – Detect single nucleotide polymorphisms (SNPs), insertions, deletions, and structural variations.

Types of Whole Genome Sequencing

1. Short-Read Sequencing (Illumina, Ion Torrent)

Provides high accuracy and is cost-effective.
Struggles with repetitive sequences and large structural variations.
Best for small genomes and variant calling.

2. Long-Read Sequencing (PacBio SMRT, Oxford Nanopore)

Can read ultra-long DNA fragments (>100 kb).
Useful for complex genomes, structural variants, and haplotyping.
Best for de novo genome assembly and resolving repetitive regions.

Applications of Whole Genome Sequencing

Medical Genetics – Identify genetic mutations linked to diseases.
Cancer Research – Detect somatic mutations in tumors.
Microbial Genomics – Study antibiotic resistance and pathogen evolution.
Evolutionary Biology – Understand species diversity and ancestry.
Agriculture & Biotechnology – Improve crop genetics and breed selection.

Advantages of WGS

Provides complete genetic information of an organism.
Identifies rare and novel mutations.
Enables personalized medicine and targeted therapies.

Limitations of WGS

High cost and computational demands.
Large amounts of data require bioinformatics expertise.

Ethical concerns related to genetic privacy.