His clinical exome analysis revealed a homozygous likely pathogenic variant in exon 4, c.200C>T (pThr67Met) in the PTS gene, causing hyperphenylalaninemia, BH4-deficient, A. There is a case series from India on BH4-deficient hyperphenylalaninemia, and it reported one patient with a PTS gene mutation and a similar phenotype as seen in our patient [19]. The gene discussed is PTS; the disease is Hyperphenylalaninemia.