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Test Code
5387
Test Name
Trichothiodystrophy NGS Panel
CPT Codes
81479
Expected Turnaround Time
Typically 2 to 4 weeks from receipt of a sample in the laboratory. All cases involving ongoing pregnancies will be expedited.
Clinical Utility
Genetic analysis to provide a molecular diagnosis of this disorder. Recommended for individuals with a personal and/or family history of this disorder to ensure appropriate treatment and establish recurrence risk for family members.
Specimen and Container Info

Non-Prenatal Specimens

Preferred/Alternate

Specimen Type

Containers

Volume

Preferred Specimen Type

Whole Blood

Lavender Top (EDTA)

3 mL

Alternate Specimen Type

Genomic DNA

1.5 mL Tube

3 µg (at a concentration of at least 30 ng/µl), preferably in TE solution.

Alternate Specimen Type

Fibroblasts

T-25 Flasks

2 confluent T-25 flasks, filled to capacity

Alternate Specimen Type

Saliva (Whole blood is recommended for CNV)

DNA Self-Collection Kit or Oragene Saliva Collection Kit for Young Children

Follow kit instructions (www.dnagenotek.com)

Prenatal Specimens

Either specimen type below is acceptable.

Specimen Type

Containers

Volume

Cultured cells

T-25 Flasks

2 confluent T-25 flasks derived from amnio or CVS samples.

Genomic DNA

1.5 mL Tube

3 µg (at a concentration of at least 30 ng/µl), preferably in TE solution.

NOTE: For specimens from outside of North America, the preferred specimen type is Genomic DNA. HNL Genomics does not recommend shipping whole blood or cultured cells from any location other than the United States, Canada, or Mexico.
Transport Instructions
  • Transport at room temperature within 24 hours.
  • If the specimen cannot be transported to the lab within 24 hours, refrigerate for up to 72 hours.
  • Do not freeze or expose to extreme temperatures, refrigerate for up to 72 hours if cannot be transported to lab within 24 hours. 
Stability Requirements

Room Temperature

24 hours

Refrigerated

72 hours
Causes for Rejection
  • Improperly labeled specimen (minimum of two patient identifiers)
  • Inappropriate specimen type
  • Incomplete or incorrect test request form
  • Insufficient volume
  • Specimen has leaked in transit
  • Specimen without a test order
Methodology
Next Generation Sequencing and Copy Number Variation Analysis
Performing Location
Genomics - Snowdrift
Alternate Names
TTD
Description

Trichothiodystrophy (TTD) is a rare autosomal recessive condition characterized by brittle, sparse hair lacking sulfur. Tiger-tail-pattern hair characterized by alternating dark and light bands under polarizing microscopy, is diagnostic for TTD. Other common findings include short stature, growth retardation, ichthyosis, dysplastic nails, dystrophic teeth, cataract, intellectual deficit, and recurrent infections. Approximately half of the affected individuals have a photosensitivite form of the disorder.

The Trichothiodystrophy NGS panel consists of six genes: ERCC2, ERCC3, GTF2E2, GTF2H5, MPLKIP and RNF113A.

Gene

Disorder

MIM

Inheritance

ERCC2

Trichothiodystrophy 1, photosensitive (TTD1)

601675

AR

ERCC3

Trichothiodystrophy 2, photosensitive (TTD2)

616390

AR

GTF2E2

Trichothiodystrophy 6, nonphotosensitive (TTD6)

616943

AR

GTF2H5

Trichothiodystrophy 3, photosensitive (TTD3)

616395

AR

MPLKIP

Trichothiodystrophy 4, nonphotosensitive (TTD4)

234050

AR

RNF113A

Trichothiodystrophy 5, nonphotosensitive (TTD5)

300953

XLD

 

 

 

 
Testing Schedule
Monday-Friday
Genes
ERCC2, ERCC3, GTF2E2, GTF2H5, MPLKIP, RNF113A
Disease Group
Hair and Nail disorders, Skin, Tooth
The American Medical Association (AMA) Current Procedural Terminology (CPT) codes published by HNL Lab Medicine are guidelines and are intended for informational purposes only. CPT coding is the exclusive responsibility of the billing entity. View the Terms.
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