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Test Code
1898
Test Name
Metaphyseal Dysplasia Without Hypotrichosis
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

RMRP related disorders - The RMRP gene encodes an RNA component of an enzyme involved in the processing of mitochondrial RNA. Mutations in RMRP have been identified in three different disorders: Cartilage-hair hypoplasia or metaphyseal chondrodysplasia, McKusick type (CHH; MIM 250250), metaphyseal dysplasia without hypotrichosis (CHHV; MIM 250460) and anauxetic dysplasia (MIM 607095). All are autosomal recessive disorders.

Cartilage-hair hypoplasia (CHH) has a variable presentation. It is a skeletal dysplasia characterized by short extremities, bowed legs, short and broad hands and feet, extreme ligamentous laxity and hypoplastic hair. Additional findings may include Hirschsprung disease, hypopigmented skin, various defects of cellular immunity and anemia. Metaphyseal dysplasia without hypotrichosis (CHHV) is an autosomal recessive disorder recognized as a variant of CHH. The phenotype of CHHV also overlaps with that of metaphyseal chondrodysplasia, Schmid type (MCDS; MIM 156500). Anauxetic dysplasia is characterized by prenatal onset of severe disproportionate short stature with an adult height of <85 cm, hypodontia and mild mental retardation. Other findings include platyspondyly, cervical dislocations, hypoplastic ilia, small epiphyses, metaphyseal flaring and brachydactyly.
Testing Schedule
Monday-Friday
Genes
RMRP
MIM
250460
Disease Group
Skeletal Disorders
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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