Disorders of amino acid metabolism


Congenital deficiency of Homogentisic acid oxidase, needed for degradation of tyrosine.Alkaptone bodies formed cause urine to turn black on standing,connective tissue also becomes black(ochronosis)

Phenyl Ketonuria(PKU)


Autosomal recessive disease.Phenyl alanine hydroxylase deficiency,phenylalanine accumulates, tyrosine becomes an essential Amino acid.Phenylketones excreted in urine.Menttal retardation,growth retardation,fair skin,eczema.

Guthrie test


Autosomal recessive,Cystathione beta synthase deficiency.Disorder of methionine metabolism,leads to increased homocysteine in plasma and urine.

Inferonasal lens subluxation,in marfans it is superotemporal lens subluxation.

Maple syrup urine disease

alpha keto acid dehydrogenase deficiency.Branched chain ketonuria, levels of leucine,Isoleucine and valine increased.CNS defects,mental retardation,death.


Inherited defect of renal tubular aminoacid transporter for cysteine,ornithine,lysine and arginine in PCT.Cysine kidney stones(Staghorn calculi)

Isovaleric acidemia

Branched chain aminoacid metabolism defect.Cheesy odour of breath and body fluids.

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