I am aware that PCA done on Gaussian distributed data (such as RNA-Seq) ensures the uncorrelatedness as well as independence of each factor. I am having difficulty understanding what the 'Gaussian distribution refers to' here.
For example in gene expression data. I have a matrix with each row indicating specific gene and each column indicating each individual. If I perform an PCA on this matrix hoping to uncover several expression patterns, what does 'Gaussian distibution' refer to here? Is it the expression of each gene in specific pattern or the expression of single gene among individual?