Abstract
Mutations in a majority of the 18 loci of the Dopa decarboxylase (Ddc) gene cluster effect similar morphological defects of the cuticle and/or catecholamine-related abnormalities. Mutations in 14 loci affect cuticle formation, cuticle sclerotization, or cuticle melanization, with mutations in 11 of these same loci (including Ddc and amd) producing melanotic psueudotumors, symptomatic, perhaps, of abnormal catecholamine metabolism. Mutations in seven of the genes perturb catecholamine pool levels during prepupal and pupal development, all of which also form melanotic pseudotumors, suggesting several of these genes may encode proteins involved in catecholamine metabolism. Thus, the Ddc gene cluster represents in higher eukaryotes an unusual example of a large cluster of functionally related genes involved in a common physiological process.
