Techniques available
IMEGEN use the most accurate and up-to-date genetic analysis techniques. The optimal diagnostic efficacy is obtained by selecting the most appropriate technique for each clinical case.
The various techniques available can be grouped on the basis of the type of genetic mutation to be identified.
Mutations in the DNA sequence
Sequencing is the process of reading the nucleotides found in a fragment of DNA or RNA.
The Sanger sequencing method is currently the gold standard for detecting variations in the sequence of genes at a diagnostic level.
Sanger sequencing is the ideal technique for analysing small fragments of DNA with high precision.
Thanks to its high specificity and sensitivity, NextGeneDx, a technique specifically developed by IMEGEN, allows the use of new massive sequencing techniques, or NGS (Next Generation Sequencing), at a diagnostic level. This proprietary technology combines the precision and specificity of Sanger sequencing with the power and lower costs of massive sequencing techniques.
NextGeneDx is the ideal technique for analysing large genes or small groups of genes associated with a disease or phenotype as precisely as possible.
The exome involves sequencing the coding regions, or exons, of all known genes in a single assay. The exome accounts for 1.5% of all the genomic information in an individual, and 85% of known disease-causing mutations are found in it.
Depending on the clinical indication or the precision with which a phenotype or clinical suspicion can be defined, analysis of all data and clinical interpretation can focus on a specific number of genes (directed exome) or all genes for which clinical information is available (IMEXOMA),thereby optimising the precision and clinical utility.
The IMEGEN Exome is a service aimed at diagnosing patients with heterogeneous genetic diseases or those of unknown aetiology.
Mutations affecting the number of DNA copies:
Individual normally carry two copies, one from their mother and the other from their father. Some diseases are associated with variations in the number of copies of certain regions in the genome. These variations may be of very different sizes, even affecting whole chromosomes (aneuploidies). They include losses (deletions) or gains (duplications) of information in certain regions of the genome or of entire chromosomes, such as monosomies (one copy) or trisomies (three copies).
MLPA (Multiplex ligation-dependent probe amplification) allows duplications or deletions in specific regions of the genome to be identified by designing molecular probes that allow them to be amplified and quantified. These technique is used to detect deletions and duplications of exons in specific genes or regions of the genome, or to detect alterations due to modification of the methylation pattern.
MLPA is the technique of choice for detecting deletions, duplications or altered methylation in genes of regions associated with specific diseases.
The CGH array is a very powerful technique that allows gains or losses of genetic material to be detected in any part of the genome in a fast and efficient manner. Its sensitivity for detecting these types of mutations is much higher than that for other techniques, such as karyotyping.
CGX is a specific design of the CGH array that is particularly useful for analysing regions associated with known clinical phenotypes or syndromes caused by variations in the number of copies, thereby increasing its clinical utility and diagnostic precision.
CGX is the ideal technique for diagnosing genetic diseases or syndromes associated with major genomic deletions or duplications.
IMEGEN 360o Dx Comprehensive, thematic panels
This design is proprietary to IMEGEN and provides the most complete analysis of the genes and mutations associated with a specific disease or phenotype, with the best diagnostic cost-efficacy ratio. Application of this technique allows the analysis of the largest number of mutational events described for each specific disease or phenotype.
| Sanger | NextGeneDx | IMEGEN 360o Dx | IMEXOMA | MLPA | CGH | |
| Point mutations and indels* | YES | YES | YES | YES | NO | NO |
| CNVs# | NO | NO | YES | NO | YES | YES |
| Sensitivity | 99.9% | 99.9% | 99% | 95% | 99 % | 97 % |
| Specificity | 99.9% | 99.9% | 99% | 99% | 97 % | 99 % |
| Genomic region analysed | Specific | Specific | Specific | Exome | Specific | Genome |
| Genomic information analysed | 0-10 kb | 5-50 kb | 50-500 kb | 0.4-12 Mb | 1-50 kb | 1Mb-3.3Gb |
| VUS | Low | Low | Medium | Medium/high | Low | Medium/high |
| Interpretation | Easy | Easy | Simple/medium | Medium/complex | Easy | Mean |
| Clinical orientation | Specific | Specific | Specific | Specific/non-specific | Specific | Non-specific |
* indel: small insertions or deletions (one or a very small number of nucleotides) observed upon analysing the sequence of a fragment of DNA.
# CNVs: CNV: copy number variation. Variations in the number of copies of a genomic region with respect to the normal number of copies (two).
Other techniques
In addition to these common types of mutations, there are other types associated with genetic diseases for which other specific techniques, some of which are described below, are required:
These mutations are caused by an increase in the number of repetitions of, normally, one trinucleotide (CAG, CTG, CGG, GAA,…) above a threshold value of repetitions. They are usually associated with neurological diseases.
The techniques used are aimed at identifying and quantifying the number of repetitions that can be considered to be normal in the population and identifying when the number of repetitions exceeds this threshold value. The detection of a pathological expansion is diagnostic for the disease.
Diseases caused by triplet expansions include dominant adult ataxias, Huntington’s disease, Friedrich’s ataxia, fragile X syndrome and myotonic dystrophy.
Numerous biological processes are regulated by DNA methylation. This process allows, amongst others, the selective activation or inactivation of certain genes or groups of genes.
Alterations in these methylation patterns and, as a result, the activation or inactivation of certain genes in different processes or circumstances are a cause of mutations in some genetic diseases.
An ability to determine the methylation pattern in certain genes or regions is of particular use for diagnosing this type of genetic disease.
Some diseases caused by methylation alterations include Prader–Willi, Angelman, Silver–Russell and Beckwith–Wiedemann syndrome, amongst others. In addition, methylation is strongly related to the regulation of oncological and metastatic processes.
Haplotype analysis involves analysing the different genetic markers located in a single genomic region in order to determine their family-based segregation.
This type of analysis is of particular interest for identifying some alterations, such as uniparental disomy or deletions of known regions.
This technique has tended to be widely used to perform ligation studies in broad families associated with a specific disease and with a specific inheritance pattern.
ISO 9001
Imegen is certified for genetic testing applied to clinical diagnosis using the following technologies: NGS sequencing, Sanger sequencing, CGH, PCR and Real Time PCR, MLPA and other molecular technologies
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