Given the task definition and input, reply with output. Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

1. In order to investigate the biological function of the human CLN3 gene that is defective in Batten disease, we created a yeast strain by PCR-targeted disruption of the yeast gene (YHC3), which is a homologue of the human CLN3 gene. 2. The phenotypic characterization revealed that the yhc3 delta mutants are more sensitive to combined heat and alkaline stress than the wild-type strains as determined by inhibition of cell proliferation. 3. This suggests that the yhc3 delta mutant is a good model to investigate the biological function of human CLN3 gene in mammalian cells and to understand the pathophysiology of juvenile Batten disease.
What is the effect of a defective CLN3 gene?