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Test Code
1690
Test Name
Witkop Syndrome
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
Description

Tooth agenesis, selective, 1 (STHAG1; MIM 106600) and Witkop syndrome (dysplasia of nails with hypodontia; MIM 189500) are both autosomal dominant disorders caused by mutations in MSX1.

Both STHAG1 and Witkop syndrome are characterized by selective tooth agenesis. Maxillary and mandibular second premolars and maxillary first premolars are the most commonly affected teeth in STHAG1. In Witkop syndrome, mandibular incisors, second molars, and maxillary canines are most often absent. Additional findings in Witkop include dysplasia of the nails and possible lip eversion. The nails are typically poorly formed in early life and may be thin and friable. They may display ridging, pitting, and koilonychias. Toenails may be more affected than fingernails. Primary teeth may be small in Witkop syndrome, but the disorder may not be detected until the permanent teeth fail to erupt. MSX1 codes for muscle segment homeobox, Drosophila, homolog of, 1 also called homeobox 7 (HOX7). Missense, nonsense, and insertion mutations have been identified in the MSX1 gene in patients with STHAG1 and Witkop syndrome.
Testing Schedule
Monday-Friday
Genes
MSX1
MIM
189500
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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