Hong Kong Genome Institute 香港基因組中心

The human body is formed in complex and profound ways. Its basic composition is identical, but each person is unique. Let us explore the world of genomics together and get to know more about how intricate the human body is.

A gene is a segment of DNA that serves as the basic unit of instruction for building our body’s observable traits and functions.

The DNA bases are linked together in a chain to form a DNA strand. Only certain sections of the chain contain genetic instructions to build our body’s observable traits and functions. By analogy, a gene is like a complete sentence or paragraph, which conveys particular meaning.

A “genome” refers to the entire set of genetic materials in a living thing. For every human being, the genome includes over 20,000 genes. Each of us has our own unique genome, which can be thought of as an operation manual for our body. It provides instructions that help to determine physical characteristics of our body such as skin colour, height and potential risks of developing different diseases.

If we think of the DNA bases as letters of the English alphabet, a gene is like a complete sentence or paragraph, and the genome is like the whole instruction manual – including all the chapters, paragraphs, sentences, graphics and even typesetting.

If we were to compare the genomes of two persons who are not related by blood, 99.9% of their genomes would be the same and only 0.1% of them would be different. However small this 0.1% might look like, it is significant enough to represent millions of differences in the two DNA sequences, accounting for each person’s unique physical characteristics.

“Whole Genome Sequencing” (WGS) technology enables us to understand more about the human genome. It includes three main steps:

1. Sequencing

As the name suggests, sequencing is the process of reading 3 billion DNA bases in the human body one by one in order.

2. Data processing

After obtaining a large amount of genomic data from sequencing, bioinformaticians have to transform them into interpretable information. They have to compare the sequenced DNA with the “Human Reference Genome”, then detect the differences between the two. These differences are called genetic variants. There are millions of genetic variants in our body, and most of which are not disease-causing. On the contrary, they are what make us unique.

3. Data Analysis

Data Analysis is the most complex and time-consuming step. It involves the identification of disease-causing variants, also called pathogenic/likely pathogenic variants, among millions of genetic variants. It requires not only the knowledge and advancement in genomic science and genomic medicine, but also a large number of cases for long-term analysis and research.

The importance of genomic data

Since the completion of the first blueprint of human genome, genomics has quickly blossomed as a field, but scientists have yet to fully resolve the complex relationships between the genome and diseases.  Therefore, more case studies with patients and genomic data are vital for research development.

To  date, most of the genomic research data came from people in Western countries with European ancestry, which may not be the most useful reference to patients in Hong Kong. To better benefit patients and their families in Hong Kong, HKGP hopes to establish a genome database of local population. This effort will also promote local genomics development as scientists and clinicians reveal and understand more links between genome and diseases.