Researchers presented 2 cases of pediatric patients with Duchenne muscular dystrophy (DMD) and low acid alpha-glucosidase (GAA) activity and high creatinine kinase (CK) levels in a study published in Frontiers in Pediatrics.
Typically, low GAA activity is associated with Pompe disease. In these cases, the infants were initially presumed to have Pompe disease. Upon genetic testing, clinicians discovered DMD gene mutations and GAA pseudodeficiency alleles. The patients were subsequently diagnosed with DMD.
Some of the symptoms of Pompe disease and DMD can overlap; hence, physicians should be cautious in arriving at a diagnosis in infants with high CK levels.
The first case was a 2-month-old infant boy who had jaundice and was discovered incidentally to have significantly high CK levels. Motor assessments were normal. Further tests revealed abnormally low GAA levels. His clinicians decided to conduct whole-exome sequencing, which revealed a DMD gene hemizygous variation but no pathogenic mutations of the GAA gene.
The patient was diagnosed with DMD. Further tests conducted on the boy’s family revealed that his parents and sister also had decreased GAA activity, with genetic testing demonstrating pseudodeficiency alleles as well.
Read more about Pompe disease etiology
The second case was a male neonate who was hospitalized for pneumonia and discovered to have significantly high levels of CK. Muscle tone and motor development assessments were normal. The patient had low blood GAA activity, but the levels were not extremely low, as is commonly seen in Pompe disease.
Whole-exome sequencing revealed a DMD gene hemizygous mutation and 2 GAA heterozygous pseudodeficiency alleles. The neonate was diagnosed with DMD. Further tests conducted on the family revealed that his mother also had high CK levels and low GAA activity.
“Pseudodeficiency alleles can cause a significant reduction in GAA activity, but no symptoms of the disease,” the authors of the study wrote. “In our two cases, their family members who had low GAA levels all had pseudodeficiency alleles but did not show any symptoms of Pompe disease.”
He X, Li X, Lin Y, et al. Duchenne muscular dystrophy with low acidic α-glucosidase activity: two case reports and literature review. Front Pediatr. 2022;10:855510. doi:10.3389/fped.2022.855510