Hawkinsinuria in two unrelated Greek newborns: Identification of a novel variant, biochemical findings and treatment

Abstract

Background: Hawkinsinuria is a rare inborn error of tyrosine metabolism. Objectives: To study novel hawkinsinuria cases by monitoring their biochemical profile and conducting a mutation analysis. Subjects and methods: Among 92,519 newborns that underwent expanded newborn screening, two unrelated cases with high tyrosine blood levels were further investigated by chromatographic techniques and via genetic testing for 4-hydroxyphenylpyruvate dioxygenase (HPD) gene. Results: Elevated levels were monitored for blood/plasma tyrosine and for the specific diagnostic markers in urine. The two newborns were put on a special low tyrosine diet. Till completion of the 1st year of their life, liver function tests and brain MRI were normal. The mutation A33T was identified in both cases, while one neonate carried an additional novel mutation of HPD gene (V212M). Conclusions: Two mutations of HPD gene, A33T, which are associated with hawkinsinuria and a novel one (V212M) were detected for the 1st time in Greek newborns.