Scientific R&D Project on Genetic Testing Service
Categories of Testing
Whole Exome Sequencing
WES
Purpose
There are about 23,000 genes in the human genome. Among these genes, whole exome that code for proteins is composed of approximate 180,000 exons. Exons in genes are responsible for producing functional proteins. Current scientific evidences reveal that most DNA mutations (about 85%) that are corresponding to diseases occur in exonic regions.
Leopard Gene applies Whole Exome Sequencing (WES) to detect genetic variations in the exome. This comprehensive genetic variation profile with professional data integration analysis provides stable and reliable analysis results and can further enhance the competitive and applicational values of clinical researches.
Whole Genome Sequencing
WGS
Purpose
In 1953, the publication of the double-stranded helix structure of DNA has made an evolutionary leap of biochemistry and biology researches. In 1972, “genetic engineering” based on bacteria genetic manipulation has provided an efficient tool for genetic researches. During 1990 to 2003, the Whole Genome Sequencing (WGS) project has successfully decoded the book of life with a length of 3 billion bases.
DNA (deoxyribonucleic acid, deoxyribonucleic acid), a giant chemical molecule, is shared by all living organisms that carries the genetic code (gene). Gene accounts for the smallest unit capable of performing various function.
Whole Genome Sequencing (WGS) is a procedure to sequence the whole DNA content of a single organism’s genome. For human WGS, a total of 3 billion bases will be sequenced. Currently, WGS has been widely applied in scientific research and clinical diagnosis.
RNAseq sequencing detecting
RNA Sequencing (RNA Seq)
Purpose
Compared with a fixed content of chromosome, transcriptome in a cell shows dynamic change with respect to cell status. With the advances of NGS technology and the increasing sequencing throughput in a single NGS run, it makes RNA-seq including detection of alternative splicing, post-transcriptional modification, gene fusion, SNP and gene expression profile possible. Nowadays, RNA-seq can be applied on mRNA transcriptome as well as total RNA and small RNA (such as microRNA, tRNA and rRNA etc.) expression profiles.
RNA-seq is one of the NGS technology used to sequence all RNA fragments in a sample. By mapping these sequencing reads to the references (genome or transcriptome references) and downstream bioinformatic analyses, general gene expression profiles can be revealed. RNA-seq can be applied to understand gene expression levels as well as to discover differentially expressed gene sets among samples.
RNA-seq can facilitate discovery of new candidate genes or function of non-coding RNAs. It can also help to understand differential expression for different RNA isoforms (alternative splicing).
At present, RNA-seq has been widely applied for gene screening in animal/plant genetic breeding and disease resistances improvement researches.
Frequently asked questions
Comparing with traditional Sanger sequencing, NGS provides very high throughput and can greatly reduce cost and data producing time per unit sequence.
NGS has a wide application. For example, it can be used to detect genetic variants associated with many inherited diseases such as congenital deafness, hereditary Parkinson’s disease, early-onset dementia, mitochondrial disease, retinitis pigmentosa, or natural jaundice. It can also be applied to detect variants that have targeted drug information or diseases that associate with multiple or a larger amount of exon variations such as familial breast cancer, familial colorectal cancer, tuberous sclerosis, Marfan syndrome, polycystic nephropathy, familial hypercholesterolemia, Wilson’s disease, Qiu Cindy’s muscular dystrophy etc. With the advance of NGS technology, these genetic test assays can be performed in a more economical and easier way by a single blood collection.
Sometimes, no genetic defect information (gene targets) can be linked to certain diseases. In these circumstances WES or WGS may be used to find the potential candidate genes (variants).
NGS can also be applied to provide contraindication warning before drug prescription for some diseases. For example, clinical evidence has been provided that before the prescription of the anti-epileptic drug, Carbamazepine, it is required to perform HLA assay in order to reduce the high risk of acquiring SJS (Stevens-Johnson Syndrome). Similar medication for uric acid-lowering drug, Allopurinol, may also perform HLA assay to prevent the high risk of SJS.
Finally, other common applications of NGS include quantitative metagenomics, detection of somatic mutations, biomarker tracking for cancer recurrency, NIPT assays, and liquid biopsy testing for cancer genes.