Test name: Postnatal High Density SNP Array
Also known as: Copy Number + SNP Array
- Autism spectrum disorders (ASD) GeneReviews™
- Developmentaldelay (DD) / Learning disability / Intellectual disability (ID)
- Congenital anomalies
- Dysmorphic facial features
- Abnormal growth parameters such as: short stature, microcephaly, macrocephaly, failure to thrive, and overgrowth
- Seizure disorders
- Vision/hearing problems
- Low muscle tone
- Neurodevelopmental and Neuromuscular disorders
- Suspicion of well-known microdeletion/microduplication syndromes, such as:
- Abnormal unbalanced karyotypes, particularly those with supernumerary marker chromosomes, or mosaic karyotypes
- Certain cytogenetic cases with abnormal ‘balanced’ karyotypes including Robertsonian translocations, inversions, and isochromosomes
- Imprinting associated disorders, such as:
- Suspected consanguinity
- A child with autosomal recessive disease, when one parent is not a carrier
- Family history of a structural chromosome abnormality or rearrangement
- Postnatal High Density SNP array, or “microarray” as it is frequently called, is a technology that analyzes the genome for copy number changes, microdeletions, or microduplications, at a higher resolution than traditional karyotyping.
- The use of SNP (single nucleotide polymorphisms) technology allows us to evaluate for isodisomy (one form of uniparental disomy) (iUPD), segmental loss of heterozygosity (LOH), and regions of homozygosity (ROH), in addition to copy number changes.
- Our laboratory’s array platform uses a total of 2.6 million markers, 1.9 million non-polymorphic copy number probes, and 750,000 SNP probes, providing a global resolution of 5 Kb to 10 Kb for copy number changes and 5 Mb resolution for regions of homozygosity.
- Due to the increased diagnostic yield of microarray, the American College of Medical Genetics (ACMG) recommends microarray as a first tier test for individuals with intellectual disabilities, autism spectrum disorders, and/or multiple congenital anomalies.
- Microarray is more comprehensive and cost effective than ordering multiple FISH tests.
- Microarray testing will NOT detect single gene mutations, including small deletions or duplications, balanced chromosome arrangements such as translocations, or low level mosaicism.
*Reference Source: ARTICLE: Chromosomal Microarray Is a First-Tier Clinical Diagnostic Test
- Autism/Intellectual Disability/Multiple Anomalies Next Generation Sequencing Panel can be ordered simultaneously as comprehensive testing or in a tiered fashion to evaluate for common single gene causes of autism spectrum disorders, intellectual disabilities, or multiple congenital anomalies.
- If trisomy 13, 18, or 21 (Down syndrome) is suspected, chromosome analysisis recommended.
- If an imprinting disorder, such as Angelman syndrome is suspected, additional testing such as methylation or targeted gene sequencing may be indicated. Recommendations for additional testing differ based on the disorder suspected.
For assistance determining which testing options are most useful for your patient, please call our laboratory at 402-559-5070 and ask to speak with a laboratory genetic counselor.
Specimen requirements: Test kits are available – please contact the laboratory
- Blood (Children/Adult): 3-5 ml blood in EDTA tube
- Blood (Newborn): minimum 1ml blood in EDTA tube
- Buccal swab: kits available upon request
- Extracted DNA: 5µg
CPT codes: 81229 and 88230
Pricing: Contact the laboratory billing staff for current costs
Required forms: Postnatal Test Request Form
Turn-around time: Results are typically available in 1-2 weeks
Step-by-step ordering instructions:
1) Access the postnatal test request form on the Human Genetics Laboratory website.
2) Complete the 2-page form. Under TEST SELECTION, mark the box next to the Postnatal High Density SNP Array, OR the Microarray/NGS Combination Testing.
3) When ordering Combination Testing, under SPECIAL TEST INSTRUCTIONS, indicate the order in which you would like the tests performed. For example, “Please complete microarray first. If negative, reflex to Next Gen Sequencing.”
4) Provide any clinical information that may be important for interpretation.
5) Obtain insurance pre-authorization when necessary; forms available.
6) Following HGL shipping & handling requirements, send completed test request form and specimen at room temperature within 24 hours of collection.