[Juvenile Pompe disease: Undescribed genotype. First report in Quintana Roo].

Background: Pompe disease (PD) is a rare autosomal recessive genetic disorder (1 in 14,000) which affects the synthesis of acid alpha-glucosidase (AGA), leading to intralysosomal glycogen accumulation in muscle tissue. The clinical presentation is heterogeneous, with variable degrees of involvement and progression, classifiable based on the age of onset into infantile (classic or non-classic) and late-onset forms (juvenile or adult). The diagnostic test of choice is the enzymatic analysis of AGA, and the only pharmacological treatment is enzyme replacement therapy (ERT). This document aims to report a clinical case of late-onset PD.

Clinical case: 14-year-old male who started at the age of 5 with postural alterations, gait changes, and decreased physical performance compared to his peers. A diagnostic evaluation was initiated in 2022 due to worsening neuromuscular symptoms, accompanied by dyspnea, tachycardia, and chest pain. A suspicion of a lysosomal storage myopathy was established, and through enzymatic determination of AGA the diagnosis of PD was confirmed. The study of the GAA gene revealed the association of 2 previously unreported genomic variants. ERT was initiated, resulting in clinical improvement.

Conclusions: The age of symptom onset, severity of clinical presentation, and prognosis of the disease depend on the specific mutations involved. In this case, the identified genetic alterations are associated with different phenotypes. However, based on the clinical presentation, it is categorized as juvenile PD with an indeterminate prognosis.