The human genome normally consists of 46 chromosomes with around 23,000 genes. Genes have regions that do not code for proteins but may have regulatory functions (e.g. introns) and those that contain the information for proteins (exons). The majority of human DNA consists of regions that are not directly responsible for protein production. Exons, on the other hand, make up less than 2% of our genetic information.

What is examined in exome sequencing?

The entirety of an organism's exons is called the exome. Whole-exome sequencing (WES) thus analyzes the regions of the genome that code for proteins. Introns or other regulatory regions are usually not included.

When is exome sequencing useful?

Exome sequencing is the method of choice in the case of

• complex non-specific symptoms or unclear diagnosis
• unclear developmental disorder
• Compilation of a personalized gene panel (based on the clinical question)

What is a trio exome?

In order to identify disease-causing variants more efficiently, a trio WES diagnosis (trio exome) can be useful. For this purpose, not only the patient's DNA but also that of the parents is analyzed.

Why is a trio exome useful?

Trio WES diagnostics increases the detection rate by, among other things, reducing the number of variants to be evaluated and more precise classification of pathogenicity by means of

• Detection of de novo variants
• Simultaneous parental segregation analysis

What is needed for exome sequencing?

For an optimal evaluation of the (trio-) WES data, detailed information about the clinic of patients is necessary, since we evaluate indication-specific data using standardized keywords (HPO terms).

What has to be considered with exome sequencing?

In the course of time, the WES data can be re-evaluated (without a new blood sample) on the basis of new scientific findings or deviating clinical findings. In minors, variants for late manifesting diseases may not be considered according to the German Gene Diagnostics Act.

In addition to exons, the human genome also includes introns, which often have a regulatory function and can also contribute to a change in gene expression. In an exome sequencing (see above), these regions are usually not considered.

What is examined in genome sequencing?

Whole-genome sequencing (WGS) analyzes both coding and non-coding regions.

When is genome sequencing useful?

WGS is excellent for identifying the rare variants that lie away from the exons as the genetic cause. WGS can therefore be used to rule out a second (intronic) variant for a recessive disease or to accurately identify breakpoints of structural variants.

A gene panel refers to the simultaneous analysis of multiple (pre-specified) genes. If there is a suspected diagnosis, panel diagnostics can therefore be a cost- and time-efficient path to diagnosis.

What is examined with panel diagnostics?

Using next-generation sequencing (NGS), we filter and evaluate genes specific to the indication. The panels are compiled and continuously updated on the basis of the current state of scientific knowledge, our many years of experience and in dialog with clinical partners.

For regions that are difficult to sequence (e.g. sequence homologies in the PKD1 gene or highly repetitive regions such as RPGR-ORF15), we have developed special NGS-based and bioinformatic methods.

Which panels are available?

Here you will always find our current panels. In addition, we can compile panels individually. Please do not hesitate to contact us if you have any questions!

If a specific disease is suspected, it may be useful to specifically investigate only one gene. An example is sickle cell anemia, which is caused by a specific (usually homozygous) point mutation in the HBB gene (c.20A>T, p.Glu7Val).

When is single gene analysis performed?

In addition to high-throughput sequencing (parallel sequencing of thousands of DNA fragments), we also offer classical DNA sequencing according to Sanger. This is used, among other things, for the detection of known familial variants or for genes that cannot be adequately analyzed by high-throughput sequencing.

Certain genetic alterations cannot be detected by DNA sequencing or can only be detected inadequately. In these cases, other methods (see below) may be required.

If a duplication or loss of gene components is the cause of a disease, an MLPA may be the appropriate diagnostic method.

What is examined with an MLPA?

MLPA (multiplex ligation-dependent probe amplification) can be used to specifically determine dose differences (deletions/duplications) of genes and individual exons as well as deviating methylation patterns.

When is MLPA used?

Standard MLPA techniques are used, for example, in the diagnosis of thalassemias, spinal muscular atrophy, hypercholesterolemia, familial breast and ovarian cancer, and short stature.

Is there an MLPA for every gene?

To date, the appropriate MLPA has not been developed for all known genes. If you would like a dose analysis of a specific gene or gene segment, we will be happy to advise you.

The cause of certain genetic diseases is an extension of specific gene segments (so-called repeats). Oftentimes these can not be mapped adequately and evaluated with conventional sequencing. Therefore, in order to obtain a reliable result, a fragment length analysis can be the method of choice.

What is a fragment length analysis?

Fragment length analysis is used to determine the length of PCR fragments in a relevant DNA section by capillary gel electrophoresis. The fragment lengths are then evaluated with a specific program based on the standards used.

When is fragment length analysis performed?

Fragment length analysis is used in cases of suspected fragile X syndrome, Huntington's disease and spinocerebellar ataxia, among others.