Pennsylvania started newborn screening for Pompe disease in February 2016. Between February 2016 and December 2019, 531,139 newborns were screened. Alpha-Glucosidase (GAA) enzyme activity is measured by flow-injection tandem mass spectrometry (FIA/MS/MS) and full sequencing of the GAA gene is performed as a second-tier test in all newborns with low GAA enzyme activity [<2.10 micromole/L/h]. A total of 115 newborns had low GAA enzyme activity and abnormal genetic testing and were referred to metabolic centers. Two newborns were diagnosed with Infantile Onset Pompe Disease (IOPD), and 31 newborns were confirmed to have Late Onset Pompe Disease (LOPD). The incidence of IOPD + LOPD was 1:16,095. A total of 30 patients were compound heterozygous for one pathogenic and one variant of unknown significance (VUS) mutation or two VUS mutations and were defined as suspected LOPD. The incidence of IOPD + LOPD + suspected LOPD was 1: 8431 in PA. We also found 35 carriers, 15 pseudodeficiency carriers, and 2 false positive newborns.
Background Mucopolysaccharidosis (MPS) IVA, also known as Morquio A syndrome, is a rare autosomal recessive lysosomal storage disorder caused by a deficiency in the enzyme N-acetylgalactosamine-6-sulfatase. Early recognition, diagnosis, and treatment of this progressive, multisystem disease by enzyme replacement therapy (ERT) can lead to improved outcomes and reduced mortality. Methods This report documents the diagnostic journey and treatment with ERT of three siblings with MPS IVA. Clinical outcome measures included growth, endurance, imaging, cardiac, respiratory, ophthalmology, and laboratory evaluations. Results Three siblings, diagnosed at 14.7, 10.1, and 3.2 years of age, demonstrated clinical improvement with weekly infusions of 2.0 mg/kg elosulfase alfa (Vimizim®, BioMarin Pharmaceutical, Novato, CA, USA). Patient 1 (oldest sibling) and Patient 2 (middle sibling) experienced a diagnostic delay of 8 years 7 months and 4 years after symptom onset, respectively. All three patients demonstrated improvements in growth, 6-min walk distance, joint range of motion, and respiratory function after 30 months of ERT. The treatment was well tolerated without any adverse events. Conclusions This case series highlights the importance of early recognition of the clinical and imaging findings that are initially subtle in MPS IVA. Early treatment with ERT is necessary to slow irreversible disease progression and improve patient outcomes. The oldest sibling experienced improvements in mobility despite severe symptoms resulting from a late diagnosis. When evaluating patients with skeletal anomalies, imaging multiple body regions is recommended. When findings such as anterior beaking of vertebrae or bilateral femoral head dysplasia are present, MPS IVA should be included in the differential diagnosis. Newborn screening must be considered for early detection, accurate diagnosis, and initiation of treatment to reduce morbidity.
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