Newborn screening for mucopolysaccharidosis type II: Lessons learned.

Area of Science:

• Biochemistry
• Genetics
• Pediatrics

Background:

• Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare genetic disorder.
• Early diagnosis and treatment of MPS II are crucial for improving patient outcomes.
• Population-based newborn screening offers a potential strategy for early detection.

Purpose of the Study:

• To evaluate the feasibility and yield of population-based newborn screening for MPS II.
• To determine the incidence of MPS II in a screened infant population.
• To identify attenuated phenotypes and facilitate cascade testing within families.

Main Methods:

• Dried blood spots from 586,323 infants were analyzed for iduronate-2-sulfatase activity.
• Infants with reduced enzyme activity were referred for diagnostic confirmation.
• Cascade testing was performed on family members of diagnosed individuals.

Main Results:

• Eight cases of MPS II were diagnosed, yielding an incidence of 1 in 73,290 births.
• At least four diagnosed cases presented with an attenuated phenotype.
• Fifty-three cases of pseudodeficiency were identified (incidence 1 in 11,062).

Conclusions:

• Newborn screening for MPS II is effective in detecting affected infants, including those with milder forms.
• The actual incidence of MPS II may be higher than previously estimated.
• Screening facilitates early intervention and family-wide diagnosis, improving management of MPS II.