Different approaches to gene sequencing
A table showing the differences between gene sequencing approaches, including the number of genes sequenced, costs, advantages and disadvantages.
Comparison of the different approaches to gene sequencing
| Targeted gene panel | Whole exome sequencing (WES) | Whole genome sequencing (WGS) | |
|---|---|---|---|
| Number of genes | 2–300+ genes. | Around 20,000 genes (1%–2% of genome). | Almost the entire genome: all coding and non-coding regions are included, though some parts – such as highly repetitive regions – are more difficult to sequence so are not routinely included. |
| Cost | £200–£700 | £750 | £1,000 (and falling) |
| Advantages | Customisable.
Lowest cost. Deep coverage (detects mosaicism). |
May identify novel genetic causes of disease.
No need to update as new genes discovered (compared with targeted gene panel). Fewer variants of uncertain significance (VUS) for analysis than WGS. |
May identify novel genetic causes of disease.
May identify disease-causing variants in regulatory intronic/ enhancer regions. Best for detecting copy number variants (CNVs) and structural rearrangements due to uniform coverage. |
| Disadvantages | Does not identify genes not already known to cause a particular gene or phenotype.
Difficult to update as new genes included. Does not detect CNVs/structural rearrangements. |
More VUS identified (compared with targeted gene panel).
Poor sequencing depth – may not detect mosaicism (compared with targeted gene panel). Misses intronic and regulatory / enhancer mutations. Increased risk of incidental findings (compared with targeted gene panel). Does not detect CNVs/structural rearrangements. |
Highest cost.
Huge data volume with requirement for secure storage. Highest chance of identifying VUS and incidental findings. Significant burden of clinical interpretation of variants identified. Increased risk of incidental findings (compared with other sequencing tests). |