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Test Code
C1565
Test Name
Hypophosphatasia, Infantile, Childhood & Adult Types
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 hypophosphatasia caused by the ALPL gene. Features include blue sclera, bowed short limbs, metaphyseal cupping, poorly formed teeth, a small thorax, and lack of skeletal ossification with fractures. There are several forms of hypophosphatasia caused by the ALPL gene which vary in severity and onset, though some individuals may be asymptomatic. Recommended for individuals with a personal and/or family history of hypophosphatasia 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

Hypophosphatasia is clinically divided into three types, all caused by defects in the ALPL gene.

 

Hypophosphatasia, infantile (MIM 241500), is a severe form with onset in utero or before 6 months of age. Inheritance is autosomal recessive. Patients may have blue sclera, bowed short limbs, metaphyseal cupping, bone spurs of the ulna and fibula, poorly formed teeth, small thoracic cage with rachitic ribs, lack of skeletal ossification with fractures, craniosynostosis, skin dimples over the apex of long bone angulations and platyspondyly. Mental retardation or development delay may also be a feature. This disorder overlaps with osteogenesis imperfecta and achondrogenesis type IA. Laboratory abnormalities include: hypercalcemia, hypercalciuria, phosphoethanolaminuria, decreased tissue and serum alkaline phosphatase and mildly elevated phosphoethanolamine. Plasma and urine inorganic pyrophosphate may be elevated.

Hypophosphatasia, childhood (MIM 241510), has a more gradual and later onset. Inheritance is also autosomal recessive. Patients share many features with the infantile form including short stature, rachitic ribs, bowed legs, skin dimples and premature loss of teeth. They may also display craniostenosis, dolichocephaly, frontal bossing, proptosis and characteristic metaphyseal radiolucency. Presentation occurs beyond 6 months of age and there may be delayed onset of walking. Laboratory abnormalities include: low alkaline phosphatase, phosphoethanolaminuria and elevated plasma and urine inorganic pyrophosphate.

Hypophosphatasia, adult type (MIM 146300) presents in middle age and may actually be asymptomatic. Inheritance can be autosomal dominant or recessive with compound heterozygosity. Patients may suffer premature tooth loss, skeletal abnormalities, osteoporosis, recurrent fractures or long bone pseudofractures, with bowed legs, bone pain or arthropathy and chondrocalcinosis. Laboratory abnormalities are similar to those described under the childhood variant.
Testing Schedule
Monday-Friday
Genes
ALPL
MIM
241500
Disease Group
Skeletal Disorders, Metabolic and Endocrine
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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