ON THE MOLECULAR NATURE OF THE DUARTE VARIANT OF GALACTOSE-1-PHOSPHATE URIDYL TRANSFERASE (GALT)

Galactosemia is an inborn error of galactose metabolism secondary to d eficiency of galactose-l-phosphate uridyl transferase (GALT). GALT is a polymorphic enzyme and Duarte (D) is the most common enzyme variant. This variant is characterized by faster electrophoretic mobility and reduced activity. Duarte/galactosemia compound heterozygotes (D/G) are commonly identified in galactosemia newborn screening programs. Howev er, these patients do not generally require treatment. By using a ''ca ndidate mutation'' approach to define the molecular basis of the Duart e variant of GALT, a close association between the previously reported N314D polymorphism and the Duarte variant of GALT was found. We sugge st that N314D encodes the D variant of GALT and that molecular testing for N314D might be useful to confirm a biochemical diagnosis of Duart e variant of GALT.