Adult-onset acid maltase deficiency in siblings

Area of Science:

• Biochemistry
• Genetics
• Neurology

Background:

• Adult form acid maltase deficiency (AMD) is a rare genetic disorder affecting muscle function.
• This condition results from a deficiency in the enzyme acid maltase, crucial for glycogen breakdown.

Observation:

• Two siblings, a 30-year-old woman and her 25-year-old sister, presented with symptoms related to AMD.
• The elder sister experienced respiratory disturbances, confirmed by muscle biopsy showing characteristic vacuoles and reduced acid maltase activity.
• The younger sister, admitted for subarachnoid hemorrhage, was found to have AMD postmortem, with basilar artery aneurysm rupture linked to vacuolar degeneration.

Findings:

• Histological and biochemical analyses confirmed adult form AMD in both siblings.
• The younger sister's aneurysm rupture was attributed to arterial wall weakening caused by AMD-related vacuolar degeneration.
• No cross-reactive immunological material against acid maltase antibody was detected.

Implications:

• This case highlights a potential link between adult form AMD and arterial aneurysms due to connective tissue abnormalities.
• Further research into the systemic manifestations of AMD, beyond muscle involvement, is warranted.
• This family represents the third reported instance of adult form AMD in Japan, contributing to the understanding of its prevalence and presentation.