What Can Be Learned From This Test
Testing is performed by sequencing the entire coding region of the TUBB4A gene. This will detect point mutations, small deletions and small insertions. It will not detect a partial or whole gene deletion or duplication.
Targeted mutation analysis for the common mutations c.745G>A; p.Asp249Asn in H-ABC or c.4C>G; p.Arg2Gly in DYT4 can be carried out. Please note on submission form if this targeted approach is being requested.
A negative test result does not rule out a genetic cause of hypomyelinating leukodystrophy, since there are many other genes associated with leukodystrophies, some of which are available for testing in our laboratory.
Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).
Turnaround time: 7-10 business days
CPT Codes and Cost
H-ABC Common Mutation Testing
Full Gene Sequencing
DYT4 Common Variant Testing
Known Variant Testing