To answer the question seriously:
The stratum germinativum (or, stratum Basal, as it is commonly called) is the bottom most layer of the epidermis. It is what is responsible for performing mitosis in order to make new epidermal skin cells (stratified squamous epithelial tissue) which eventually make their way up to the top of the epidermis, where they are keratinized and eventually flake off by exfoliation/naturally.
I'm not sure about the disease part though, sorry =/
EDIT: Actually, I lied. Basal Cell Carcinoma, as I recall, is the "best" form of skin cancer, and involves the Basal layer of skin. However, I'm no oncologist so I can't really help you further with that =(