<prompt> True regarding PKU is all except:-Due to deficiency of phenyl alanine hydroxylaseNeurological symptoms are due to excess phenyl alanineBlood phenyl alanine level 20 mgdl causes severe diseaseMethod of choice for screening is urinary phenyl alanine by Guthrie;s test  <response>: Diagnosis of PKU was detected by screening the new-born babies for the increased plasma levels of phenylalanine PKU, 20-65 mgdl; normal 1-2mgdl. This was carried out by Guthrie test, which is a bacterial Bacillus subtilis bioassay for phenylalanine. Phenylpyruvate in urine can be detected by ferric chloride test a green colour is obtained. Method of Choice is Tandem Mass Spectrometry, also for all the Inborn metabolic Error disease 