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Clinical exome sequencing of single-gene disorders

Overview - What are single-gene disorders?

The use of whole exome sequencing (WES) for diagnostics purposes has increasingly gained credibility over the past years.  Applying next-generation sequencing (NGS) to locate genetic variants in exons has proven to be particularly useful for improving our understanding about common disorders, cancers and monogenic or Mendelian diseases.
Whole exome sequencing has been especially beneficial for discovery of genetic causes underlying Mendelian phenotypes. There is an estimated number of 6,000 to 8,000 Mendelian diseases, which include cystic fibrosis, sickle cell anemia and Huntington’s disease. These disorders  are caused by mutations in a single gene and although considered rare individually, the diseases collectively occur at a rate of 40 to 82 per 1,000 live births. Approximately 7.9 million children are born annually with a birth defect due to a genetic or partially genetic cause. Most Mendelian disorders tend to run in families, although a substantial number are caused by de novo events.

 

Applications - What are the advantages of exome sequencing of single-gene disorders

Thus far, many genes that are responsible for Mendelian phenotypes have been discovered through methods like Sanger sequencing. Although applications of whole exome sequencing (WES) in clinical diagnostics are still relatively new, the technique has been used to identify many genes in Mendelian disorders. Use of clinical WES is increasingly supported by large cohort studies. For example, recent large scale clinical WES studies have shown that exome sequencing can lead to a successful molecular diagnosis in up to 25% of patient cases.

The usefulness of performing exome sequencing is evident in several areas of clinical care:

  • Identification of the causative variant underlying a particular monogenic disorder allows for gene-specific prognostication based on cases reported in literature.
  • WES can help facilitate genetic counseling by enabling more accurate estimates of recurrence risk in the family.
  • Genetic information can contribute to guiding subsequent pregnancies or identifying other at-risk family members. 
  • Targeted molecular therapy may be available for the specific genetic mutation that can help to improve patient outcomes.

 

Products related to Exome sequencing of single-gene disorders

For clinical researchers looking to utilize the WES approach in their own studies, Eurofins Genomics offers a complete service package with INVIEW Core Exome (37 Mb) or the INVIEW Whole Exome (60 Mb). The products offer highly efficient exome capture and high fidelity NGS on the Illumina platform and professional BioIT analysis, including optional use of QIAGEN’s Ingenuity Variant Analysis tool.

Did you know that we at Eurofins Genomics offer broad range of next generation sequencing services, such as the INVIEW Transcriptome Ultra Low.

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