Hereditary Multiple Exostoses (HME)

Individuals with hereditary multiple exostoses (HME) often develop benign cartilage-capped tumors (exostoses) at the ends of the long bones or the surface of flat bones. Exostoses develop prior to skeletal maturity only. Bony deformity, bowing of the long bones, limited range of motion, and premature osteoarthrosis may be associated with HME. Exostoses also may cause complications by putting pressure on nearby issues, nerves or blood vessels. A rare but severe risk in patients with multiple exostoses is the development of malignant chondrosarcoma, which occurs in 1-5% of patients. Mutations in the EXT1 gene seem to be associated with a more severe disease and higher risk of developing chondrosarcoma than EXT2 gene mutation.

Tests Available

Forms and Documents

Test Details

  • Confirmation of the clinical diagnosis
  • To differentiate between the disorders presenting with osteochondromas
  • Prenatal diagnosis in at-risk pregnancies


3 weeks
2-5 mL Blood - Lavender Top Tube
Buccal Swabs | Extracted DNA

*Reporting times are typical, but could be extended in situations outside GeneDx's reasonable control.


81406x1, 81479x1
For price inquiries please email

**The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.


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