Newborn screening for Pompe disease in Indiana resulted in the identification of 2 infants with infantile-onset Pompe disease (IOPD) and 6 infants with the potential risk of late-onset Pompe disease (LOPD).
These results and subsequent patient management were detailed in a poster abstract published in Genetics in Medicine and presented at the American College of Medical Genetics and Genomics Annual Clinical Genetics Meeting 2022.
One of the infants with IOPD was cross-reactive immunologic material (CRIM)-positive and began treatment with 40mg/kg weekly of alglucosidase alfa (Lumizyme®) at 3.5 weeks of age. He continues to have a normal echocardiogram and normal levels of urine glucose tetrasaccharide and creatine kinase (CK) levels.
The second newborn with IOPD was CRIM-negative with elevated CK levels of 685 U/L. He was treated with immune tolerance induction therapy with rituximab, oral methotrexate, and intravenous immunoglobulins followed by treatment with alglucosidase alfa at 3 weeks of age. After 2 months of treatment, the patient’s CK levels had decreased to 119 U/L.
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The presenters said that there are no consensus guidelines on when to initiate treatment for patients with LOPD showing early symptoms and so their clinic arranged for regular surveillance of the 6 patients with LOPD. The surveillance included an evaluation by a neuromuscular specialist and physical therapist every 3 months, a baseline echocardiogram, regular CK level monitoring, and a swallowing evaluation by a speech therapist.
“We noticed a lack of strong data regarding the appropriate time to start Lumizyme in infants with LOPD showing early symptoms,” the authors said. “Given that we know infants with IOPD can suffer from irreversible muscle damage, we want to ensure that the window of optimal treatment in infants with LOPD, which is much less well defined, is not missed.”
In the patients with LOPD, the physicians found that the (Cr/Crn)/GAA ratio correlated with the severity of the disease with patients who had a higher ratio closer to patients with IOPD exhibiting earlier symptoms.
Of the patients with LOPD, 1 with 3 variants of the GAA gene was started on alglucosidase alfa after echocardiograms revealed borderline left ventricular hypertrophy. Persistent mild elevations of CK levels were observed in 2 of the patients with LOPD but treatment has not been initiated yet. Another 2 patients have been asymptomatic with normal CK levels and echocardiograms, and the final patient transferred out of state and was referred to a local genetics department.
McPheron M, Sapp K. eP026: Newborn screening for Pompe disease: the Indiana experience. Poster presented at: American College of Medical Genetics and Genomics Annual Clinical Genetics Meeting 2022; March 22-26, 2022; Nashville, TN.