Background: Bile acid synthesis impairments are difficult to diagnose due to non-specific manifestations related to progressive failure to absorb essential fatty acids and fat soluble vitamins and failure to maintain normal intestinal microbiota.
Case Report: A 70-year-old female presented with long-standing history of recurrent headaches, indigestion, dry, scaly, itching skin, and fluid around knee joints. Quantitative Electroencephalography (QEEG) revealed widespread excess theta maximum in the temporal regions. A rare pattern of elevated plasma glycine and taurine led to suspicion of BAATD. A stool profile employing molecular probes for commensal bacteria revealed elevation of Fusobacteria spp. Implementation of bile acid replacement therapy (BART) produced rapid remission of headache and other symptoms and a three-month follow up stool profile revealed normalization of fecal Fusobacteria populations that remained normal after one year of BART. QEEG analyses 4 weeks following BART showed evidence of significant improvement in CNS functioning.
Conclusions: This case illustrates the potential for diagnosis of latent, adult BAATD by finding a unique pattern of plasma amino acids and monitoring of therapy by observing normalization of fecal commensal bacteria and functional brain assessments.

Keywords: plasma glycine, plasma taurine, bile acid amino transferase, chronic intractable headache, indigestion, dry, scaly skin, intestinal dysbiosis, fecal microbes, bile acid replacement therapy, quantitative electroencephalography