Abstract
BackgroundThe necessity of early treatment for lysosomal storage diseases (LSDs) has triggered the development of newborn screening for LSDs in recent years. Here we report the first 70,000 newborns screened for Mucopolysaccharidosis (MPS) type 4A (Morquio syndrome) and other LSDs by an 8-plex assay including the original 4-plex LSD screening tandem mass spectrometry (MS/MS) assay for Pompe disease, Fabry disease, Gaucher disease, and MPS I disease.MethodsThe additional reaction for MPS II, MPS 3B, MPS 4A, and MPS 6 enzymes was performed separately from the 4-plex reaction. The two reactions were quenched and extracted, then combined before carrying out a single 2-min UPLC-MS/MS analysis.ResultsFrom Mar. 2018 to Apr. 2019, 73,743 newborns were screened with the 8-plex LSD screening assay. The 8-plex assay revealed a better analytical precision than the previous 4-plex assay possibly because the 8-plex was carried out using UPLC-MS/MS. Six newborns were found to have low MPS-4A enzyme (N-acetylgalactosamine-6-sulfatase) activity and biallelic GALNS pathogenic mutations in trans; these patients are presumably affected with MPS4A, making an incidence of one in 12,291 (95% confident interval (CI): 5633-26,817). One mutation, c.857C > T (p.T286 M) of the GALNS gene, accounted 5 of the 12 mutated alleles. These newborns had immature vertebral bodies at 1 month of age, and one case was treated with elosulfase alfa 2 mg/kg/week starting from 4 months of age. Among other MPSs screened, one case of MPS I, 3 cases of MPS II, and 3 cases of MPS 3B were detected. One case of mucolipidosis type III was also diagnosed. In conjunction with another 9 patients of Pompe disease, Gaucher disease, and classical Fabry disease, making an incidence of LSDs as one in 3206 newborns (95% CI: 2137 - 4811). The one with infantile-onset Pompe disease and the one with Gaucher disease were treated since the age of 8 days and 41 days respectively.ConclusionsRoutine newborn screening of MPS 4A and other LSDs were made possible by the 8-plex LSD screening assay. However, detailed phenotype prediction and the time to start treatment will need further elucidation.
Highlights
The necessity of early treatment for lysosomal storage diseases (LSDs) has triggered the development of newborn screening for LSDs in recent years
Because LSDs often lead to irreversible damage to the cells and tissues, such as damages to the skeletal muscle, bones (eq in a few types of mucopolysaccharidosis (MPSs)), and the nervous system, these diseases can be devastating at the time of clinical recognition of symptoms
Newborn screening for LSDs enables early initiation of treatment, and a multiplex platform is needed for screening several LSDs simultaneously
Summary
The necessity of early treatment for lysosomal storage diseases (LSDs) has triggered the development of newborn screening for LSDs in recent years. We report the first 70,000 newborns screened for Mucopolysaccharidosis (MPS) type 4A (Morquio syndrome) and other LSDs by an 8-plex assay including the original 4-plex LSD screening tandem mass spectrometry (MS/MS) assay for Pompe disease, Fabry disease, Gaucher disease, and MPS I disease. Our initial LSD screening assays for Pompe and Fabry diseases were conducted using fluorescence substrates [5], with little potential for further multiplexing. We changed to the 4-plex LSD screening tandem mass spectrometry (MS/ MS) assay for Pompe disease, Fabry disease, Gaucher disease, and MPS I [6]. The method has been validated by a pilot study in Washington state, USA, using de-identified dried blood spots [7]
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