Hyperphenylalaninaemias in Estonia: Genotype–Phenotype Correlation and Comparative Overview of the Patient Cohort Before and After Nation-Wide Neonatal Screening

The present study provides a retrospective overview of the cohort of phenylketonuria (PKU) patients in Estonia. Based on the available data, the patients clearly cluster into two distinct groups: the patients with late diagnosis and start of therapy (N = 46), who were born before 1993 when the national newborn screening programme was launched, and the screened babies (N = 48) getting their diagnoses at least in a couple of weeks after birth.