A Barr body is absent in the somatic cells of an individual with:

The number of Barr bodies in a somatic cell is determined by the formula:
$$\text{Number of Barr bodies}=\text{Total number of X chromosomes}-1$$

Let's evaluate the cases:

* Klinefelter syndrome has a karyotype of $47,\text{XXY}$. Number of Barr bodies = $2-1=1$.
* Triple X syndrome has a karyotype of $47,\text{XXX}$. Number of Barr bodies = $3-1=2$.
* Turner syndrome has a karyotype of $45,\text{X}$. Number of Barr bodies = $1-1=0$.

Since the count is zero, the Barr body is absent in individuals with Turner syndrome.