The fly genetic locus as well as other names for the gene are well summarized on the National Institutes of Health's National Library of Medicine, National Center for Biotechnology Information: https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=DetailsSearch&Term=35292
The gene responsible is involved 6-pyruvoyltetrahydropterin synthase.
In humans, mutations in related genes presents as BH4-deficient hyperphenylalaninemia A and phenylketonuria. In the former, there are neurotransmitter deficiencies as well as the accumulation of phenylalanine seen in the latter (Shintaku H. Disorders of tetrahydrobiopterin metabolism and their treatment. Curr Drug Metab. 2002 Apr;3(2):123-31. doi: 10.2174/1389200024605145. PMID: 12003346.)
