Gene: TRPV4
Protein: Transient receptor potential cation channel, subfamily V, member 4
Clinical characteristics:
- Congenital distal spinal muscular atrophy
- Congenital weakness of lower limbs
- Weakness of pelvic girdle and trunk may or may not be present
- Congenital contractures may or may not be present
- Non-progressive
- Scapuloperoneal spinal muscular atrophy (also known as neurogenic scapuloperoneal amyotrophy)
- Congenital amyoplasia
- Progressive scapuloperoneal atrophy and weakness
- Laryngeal palsy
- Hereditary motor and sensory neuropathy, type IIC (also known as Charcot-Marie-Tooth disease type 2C)
- Progressive weakness of limb, diaphragm, intercostal, and laryngeal muscles
- Sensory involvement may be mild or asymptomatic
Inheritance pattern: Autosomal dominant
What this test can tell us:
Mutations in exons 5 and 6 of TRPV4 have been associated with the three neuromuscular disorders listed above, which show overlap in their clinical symptoms. Testing can be performed by sequencing exons 5 and 6, or by sequencing the entire coding region. This will detect point mutations, small deletions, and small insertions. It will not detect a partial or whole gene deletion or duplication.
TRPV4 is the only gene known to be associated with these specific disorders. A negative test does not rule out a genetic cause of neuromuscular problems, as there are many other genes associated with different types of neuromuscular disorders.
Certain mutations in exons 6 and 11 through 16 of TRPV4 have been associated with 3 specific types of autosomal dominant skeletal dysplasias. One of these mutations may be identified during this test. This will be reported to the ordering provider.
Sample requirements: Draw one or two 4-cc tubes of blood in EDTA/ purple top tube (minimum of 1-2 cc for infants)
Turn-around time: 10-14 days
CPT codes and cost:
Sequencing of exons 5 & 6 only:
83891 (x1) 83898 (x2) 83904 (x4) 83912 (x1) $150
Sequencing of all exons:
83891(x1) 83900(x1) 83901(x2) 83898(x2) 83904(x28) 83912(x1) $1400
TRPV4-Related Neuropathies Testing Packet