A rare disorder of phenylalanine metabolism, an inborn error of amino acid metabolism, characterized by the development of microcephaly, growth retardation, congenital heart disease, facial dysmorphism and intellectual disability in nonphenylketonuric offspring of mothers with excess phenylalanine (Phe) concentrations.

A fold of skin starting above the medial aspect of the upper eyelid and arching downward to cover, pass in front of and lateral to the medial canthus.