Pelizaeus-Merzbacher-Like Disease
Also known as: hypomyelinating leukodystrophy 2 (HLD2)
Gene: GJC2 (previously known as GJA12)
Protein: gap junction gamma-2 protein (also known as connexin 46.6)
Clinical Characteristics
- Symptoms resemble Pelizaeus-Merzbacher disease and can include:
- Nystagmus
- Hypotonia
- Diffuse leukoencephalopathy
- Cognitive impairment may or may not be present
- Progressive spasticity
- Ataxia
- Choreoathetosis
- Dysarthria
- Pharyngeal weakness and stridor
- Head titubation
- Brainstem auditory evoked potentials are present in PMLD (typically absent in PMD)
Inheritance pattern: Autosomal recessive
What Can Be Learned From This Test
Testing is performed by sequencing the entire coding region of GJC2. This assay will detect point mutations, small deletions and small insertions. To date (December 2014), no reports of whole gene duplications or deletions have been documented in the literature.
There is a report in the literature that autosomal dominant missense mutations in GJC2 cause lymphedema (Ferrell et al., AJHG 86:943-948, 2010).
A negative test does not rule out a genetic cause of a leukodystrophy. There are many other genes associated with different types of neurologic disorders and leukodystrophies, some of which are available for testing in our laboratory and can be performed if clinically indicated.Â
Sample Requirements
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 10-14 business days
CPT Codes and Cost
Full Gene Sequencing
- Code: 81479
- Cost: $575
Known Variant Testing
- Code: 81479
- Cost: $225