Glycogen storage diseases (GSDs) are a group of inherited metabolic disorders that affect the body's ability to store or break down glycogen, a form of glucose the body uses for energy. With early diagnosis and management, individuals with GSD can lead relatively normal lives, though some types can cause long-term complications, including muscle or heart problems.

• Cause: Caused by mutations in genes that produce enzymes involved in glycogen metabolism. These enzymes are responsible for either breaking down glycogen into glucose or synthesizing glycogen for storage. Different types of GSD exist based on which enzyme is affected (e.g., GSD type I – deficiency in glucose-6-phosphatase, GSD type II – deficiency in acid alpha-glucosidase).

• Features: Symptoms vary by type but often include low blood sugar (hypoglycemia), muscle weakness, fatigue, growth problems, enlarged liver (hepatomegaly), and in some cases, heart issues or other organ involvement.

• Diagnosis: Diagnosed through genetic testing, enzyme assays, or liver biopsy, often in conjunction with clinical symptoms.

• Treatment: Treatment varies by the type of GSD but generally includes dietary management (frequent meals, high-protein or high-carbohydrate diets, sometimes feeding tubes), medications to manage blood sugar levels, and sometimes organ-specific therapies (e.g., enzyme replacement therapy for certain types).