Hereditary Multiple Osteochondromas Sequencing

Hereditary multiple osteochondromas (HMO), also known as hereditary multiple exostoses (HME) are benign cartilage-capped bone tumors (exostoses) that grow outward from the metaphyses of long bones. HMO can lead to the shortening and bowing of bones; affected individuals often have a short stature. Depending on their location the exostoses can cause the following problems: pain or numbness from nerve compression, vascular compromise, inequality of limb length, irritation of tendon and muscle, as well as a limited range of motion at the joints upon which they encroach, and premature osteoarthrosis.(1) The lifetime risk for malignant osteochondrosarcoma is low (1-5%), but the risk increases with age.(2)

HMO is an autosomal dominant hereditary disorder. This means that a patient with HMO has a 50% chance of transmitting this disorder to his or her children. Most individuals with HMO have a parent who also has the condition, however, approximately 10% -20% of individuals with HMO have the condition as a result of a spontaneous mutation and are thus the first person in their family to be affected.(3)

HME has thus far been linked with mutations in three genes.

  • EXT1 which maps to chromosome 8q24.1(3)
  • EXT2 which maps to 11p13 (4)
  • EXT3 which maps to the short arm of Chromosome 19 (5)

Our laboratory provides sequencing for EXT1 and EXT2.

Methodology: Sequencing of entire coding region

Purpose: Confirmation of Clinical Diagnosis

ICD-9 Code 756.4

Test Requisition: Sequencing Requisition

CPT Code: 81479 Cost: $738.00 each test. If sequencing both genes cost $1278.00

Turn-around-time: 4-5 weeks