Generating non-random data according to an already existing dataset and applying it to another dataset

Generating non-random data according to an already existing dataset and
applying it to another dataset

I am looking for a package in R or a tool that could help me generate data.
I have 1 dataset that has only one element and then I have a second
dataset that has approx. 450 elements. I obviously can't perform a T-test
with what I have, therefore I have to generate "artificial" data in my
first dataset in accordance with the elements from my second dataset.
Background: The first dataset with the one element corresponds to the
expression of a mutated gene for one patient and the second dataset
corresponds to the expression of the same gene that has not been mutated
for several patients.
I tried searching for solutions but I only found options for resampling
already existing data or creating new random data, which I do not want to
do.
Thank you for your help!