Genotyping

Genotyping analyses are performed in order to detect single nucleotide poly morphismens (SNP). SNPs are sites in DNA that differ by a single base (transition, transversion) leading to either a genetic marker or a disease determining mutation. Markers may be used for Whole Genome Association studies (WGA) or Linkage Disequilibrium (LD) studies eventually leading to chromosomal regions involved in a disease state.

Cytogenetics studies are performed to identify structural changes in DNA, such as copy number changes. Individuals typically have two copies of the genome in each of their cells: one inherited from the mother, and one inherited from the father. Chromosomal abnormalities are common in several disease states such as:

• Deletions: when one or both copies of a particular chromosome region are lost.
• Gains: when a chromosome or chromosomal region is duplicated or multiplied.
• Uniparental Disomies (UPDs): when two copies of a chromosome or chromosomal region are present, but both have been inherited from a single parent.

Affymetrix SNP 6.0 arrays contains ~1’000’000 probes for SNPs identification (genotyping) as well as ~900’000 non polymorphic probes for copy number estimation enabling the detection of loss of heterozygosity (LOH), which can be used to detect UPDs.

Contacts

Stefan Neuenschwander