Table 4.

Mucopolysaccharidosis newborn screening: major concerns

Enzyme activity	• No correlation genotype/phenotype • False positive in pseudodeficiency • False positive in heterozygosity
Molecular genetic analysis	• New variants of uncertain pathogenetic effect • Mild phenotypes (medicalizing, anxiety, unneeded treatment, genetic counseling)
Treatment	• Partial benefit to treatment • Late-onset/asymptomatic form