We are searching data for your request:

**Forums and discussions:**

**Manuals and reference books:**

**Data from registers:**

**Wait the end of the search in all databases.**

Upon completion, a link will appear to access the found materials.

Upon completion, a link will appear to access the found materials.

According to Wikipedia's definition, "a gene signature is a group of genes in a cell whose combined expression pattern is uniquely characteristic of a biological phenotype or medical condition."

While the above definition is very useful to understand the concept, I am looking for a "more practical" definition or, rather, a mathematical representation (e.g., a vector) of gene signatures. Hence my question.

There are mathematical definitions of "gene signature". Please have a look at the supplemental material of Subramanian et al. PNAS 2005, one of the first papers on "gene signatures", and a method and tool which is still commonly used in basic research.

*Note that Subramanian et al. have multiple definitions and that copying them here would exceed the scope of this page.*

There is no mathematical definition of genetic signature. Please first have a look at Is there a formal definition of signature of natural selection?. As explain the term genetic signature is used in a very broad sense.

There are a number of processes for which one might be looking for a signature of this process. Such signature can take the form of various statistics. For example, a historically important statistics is Tajima's D defined as

$$D = frac{Pi - S/a}{SE}$$

, where $Pi$ is the average number of pairwise differences between two randomly sampled haplotypes, $S$ is the number of segregating sites, $a=sum_i^{k-1}1/i$, where $k$ is the number of sampled haplotypes. $SE$ is the standard error for the numerator which takes a complicated formulation (have a look at Tajima 1989 for more information).