E79.2
BillableMyoadenylate deaminase deficiency
HCC Category Mapping
V24HCC 23 — Other Significant Endocrine and Metabolic Disorders
0.230ESRDHCC 23 — Other Significant Endocrine and Metabolic Disorders
0.000RxHCCHCC 43 — Other Significant Endocrine and Metabolic Disorders
0.000What This Code Means
A rare genetic disorder affecting muscle metabolism that can cause muscle pain, weakness, and exercise intolerance.
Coding Tips
- •Document whether symptoms are present or if this is an incidental finding
- •May be associated with myalgia or muscle weakness that should be coded separately
Clinical Significance
Myoadenylate deaminase deficiency (MAD deficiency) is the most common metabolic myopathy, affecting approximately 2% of the population. While many carriers are asymptomatic, affected individuals experience exercise-induced muscle pain, cramping, and early fatigue due to impaired purine nucleotide cycling in skeletal muscle.
Documentation Requirements
- ✓Provider diagnosis of myoadenylate deaminase deficiency
- ✓Confirmatory testing: muscle biopsy with histochemical staining showing absent MAD activity, or AMPD1 gene mutation
- ✓Forearm ischemic exercise test results if performed (absence of ammonia rise)
- ✓Symptom documentation: exercise intolerance, myalgia, cramping, early fatigue
- ✓Exclusion of other myopathies
- ✓Activity modification plan and symptom management
Commonly Confused Codes
G72.9 — Myopathy, unspecified: MAD deficiency is a specific metabolic myopathy, not an unspecified oneM79.1 — Myalgia: symptom code only; use E79.2 for the underlying metabolic causeE79.89 — Other disorders of purine and pyrimidine metabolism: for purine disorders that are not specifically MAD deficiencyG71.14 — Myotonic dystrophy: different myopathy that may cause similar exercise intolerance
Code Hierarchy
└E79Disorders of purine and pyrimidine metabolism└E79.2Myoadenylate deaminase deficiency
└E79.2Myoadenylate deaminase deficiency