Hypomyelinating Leukodystrophy 11

Gene: POLR1C

Protein: DNA-directed RNA polymerases I and III subunit RPAC1

Clinical Characteristics

  • Similar to disorders (HLD7 and HLD8) due to mutations in POLR3A and POLR3B
  • Delayed motor development
  • Loss or lack of independent ambulation
  • Tremors
  • Ataxia, other signs of cerebellar dysfunction
  • MRI findings:
    • Thin corpus callosum
    • Hypomyelination
    • With or without cerebellar atrophy
  • Some individuals may have:
    • Intellectual disability
    • Dental abnormalities
    • Hypogonadotropic hypogonadism
    • Myopia
  • Onset typically in early childhood
  • Different mutations in POLR1C are associated with autosomal recessive Treacher-Collins  syndrome

Inheritance pattern: Autosomal recessive

What Can Be Learned From This Test

Testing is performed by sequencing all exons and at least 25 base pairs of the surrounding intronic regions of the POLR1C gene. This will detect point mutations, small deletions, and small insertions. It will not detect a partial or whole gene deletion or duplication. To date, no large deletions or duplications have been reported.

Sample Requirements

Draw 2ml–4ml of blood in EDTA/purple-top tube (minimum of 1ml–2ml for infants).

Turn-around time: 10-14 business days per tier

CPT Codes and Cost

Full Gene Sequencing

  • Code: 81479
  • Cost: $350

Known Variant Testing

  • Code: 81479
  • Cost: $225

Additional Information