Plasma and urine acylcarnitine analysis can also be informative. Molecular analysis, including gene sequencing and copy number analysis of "GCDH" can be performed to confirm the diagnosis. Molecular testing can also provide information for family planning and prenatal testing, if desired. Like many other organic acidemias, GA1 causes carnitine depletion. Whole-blood carnitine can be raised by oral supplementation. However, this does not significantly change blood concentrations of glutarylcarnitine or esterified carnitine, suggesting that oral supplementation is suboptimal in raising tissue levels of carnitine. In the field of clinical nutrition, researchers come to the same conclusion, that oral carnitine raises plasma levels but doesn't affect muscle carnitine, where most of it is stored and used. Dietary control may help limit progression of the neurological damage. Formulas such as "XLys, XTrp Analog", "XLys, XTrp Maxamaid", "XLys, XTrp Maxamum" or "Glutarex 1" are designed to provide amino acids other than lysine and tryptophan, in order to tentatively prevent protein malnutrition. The entry of tryptophan to the brain is crucial in the proper synthesis of the neurotransmitter serotonin in the brain. One way to acutely cause depression or bulimia or anxiety in humans, in order to assess an individual's vulnerability to those disorders, is to supplement with a formula with all or most amino acids except tryptophan. The protein synthesis elicited by the amino acids leads circulating amino acids, including tryptophan, to be incorporated into proteins. Tryptophan thus lowers in the brain as a result of the protein synthesis enhancement (causing circulating tryptophan to lower more than other amino acids), and perhaps also competition of large neutral amino acids for transport across the blood–brain barrier through the large neutral amino acid transporter 1 (LNAA1). The consequence is acute tryptophan depletion (ATD) in the brain and a consecutive lowering of serotonin synthesis. ATD, which is basically a diagnostic procedure, is not a treatment for GA1. In the Amish community, where GA1 is overrepresented (Morton, 2003), patients with GA1 did not and still don't receive tryptophan-free formulas, neither as the sole source of amino acids, nor as a supplement to protein restriction. Doctor D. Holmes Morton, the 1993 Albert Schweitzer Prize for Humanitarianism laureate, is taking care of patients affected with GA1 and other metabolic diseases in this community in his Clinic for Special Children.  5-hydroxytryptophan, the precursor of serotonin that is not metabolized to glutaryl-CoA, glutaric acid and secondary metabolites, could be used as an adjunct to selective tryptophan restriction, considering the risks associated with the procedure.