LETTER OF MEDICAL NECESSITY FOR CHROMOSOME MICROARRAY ANALYSIS (180k Oligo array or
SNP+CGH array)
Date:
Date of service/claim
To:
Utilization Review Department
Insurance Company Name, Address, City, State
Re:
Patient Name, DOB, ID #
ICD-9 Codes: (list codes)
This letter is in regards to my patient and your subscriber, First, Last Name, requesting full coverage of
medically-indicated genetic testing (chromosomal microarray analysis) to be performed by Ambry
Genetics Corporation.
The diagnosis of intellectual disability (ID) is based on three main criteria: onset of symptoms before the
age of 18, intellectual abilities significantly lower than average, and reduced adaptive skills. Individuals
with ID may also have congenital anomalies and developmental delay. The majority of cases of intellectual
disability and/or developmental delay are due to an underlying genetic cause. Chromosome abnormalities,
like those found by chromosomal microarray (CMA), are the single most common cause of intellectual
disability/developmental delay with an up to 40% yield among affected patients.1,2,3 For this reason, CMA
has been recommended as a first-line test for these types of indications.4,5
Significant aspects of my patient’s personal and/or family medical history that raise reasonable
suspicion of an underlying genetic diagnosis are as follows:



Due to the heterogeneous nature of my patient’s symptoms, there is a reasonable probability of
detecting a causative chromosomal abnormality using this test. Per American Academy of
Pediatrics and American College of Medical Genetics and Genomics guidelines, CMA analysis is
recommended as a first-tier test for my patient.3,4
CMA via array-based comparative genomic hybridization (aCGH) allows for high resolution genome-wide
detection of unbalanced structural and numerical chromosomal abnormalities. This analysis can be done
using two different platforms: 180k Oligo array or SNP+CGH array. Both detect copy number variations
(deletions and duplications) within chromosomes that routine karyotyping may miss. In addition, CMA may
be clinically useful for the detection of microdeletions/microduplications in a specific gene(s) in patients
that are negative for point mutations or small intragenic aberrations. SNP+CGH arrays can also detect copy
number neutral variations such as regions of homozygosity (ROH) and uniparental disomy (UPD), which
can cause certain genetic disorders.
CMA has a significant likelihood of providing my patient and his/her family with an accurate
diagnosis, thereby ensuring appropriate medical management. In many cases, a diagnosis can lead to a
specific treatment or management strategy that dramatically changes the clinical outcome. A diagnosis can
help identify necessary medical referrals, screening for associated complications, and recurrence risk
counseling. Once a diagnosis is made, the costs associated with further testing are also likely to decrease.
Due to these benefits, CMA analysis is medically warranted in my patient.
Due to the medical risks associated with chromosomal alterations and available interventions, this
genetic testing is medically indicated. As such, I am ordering this medical necessary testing and
affirm that my patient has provided informed consent for genetic testing.
A positive test result would confirm a genetic diagnosis and/or risk in my patient, and would ensure my
patient is being managed appropriately. I am specifying Ambry Genetics Corporation because this
laboratory has highly-sensitive and cost-effective CMA analysis, along with a large database of tested
patients to ensure highly validated, accurate, and informative test interpretation.
I recommend that you support this request for coverage of CMA analysis in my patient. Depending on the
exact test ordered, genetic testing can take up to several months to complete and the laboratory will not bill
until testing is concluded. Therefore, we are requesting that the authorization be valid for 4 months.
Thank you for your time and please don’t hesitate to contact me with any questions.
Sincerely,
Ordering Clinician Name (Signature Provided on Test Requisition Form)
(MD/DO, Clinical Nurse Specialist, Nurse-Midwives, Nurse Practitioner, Physician Assistant, Genetic
Counselor*)
*Authorized clinician requirements vary by state
Test Details
CPT codes:
81228x1 (for 180k Oligo array); 81229x1, 81405x2 (for SNP +CGH array)
Laboratory:
Ambry Genetics Corporation (TIN 33-0892453 / NPI 1861568784), a CAP-accredited and
CLIA-certified laboratory located at 15 Argonaut, Aliso Viejo, CA 92656
References:
1. Flint J, et al. The detection of subtelomeric chromosomal rearrangements in idiopathic mental
retardation. Nat Genet. 1995 Feb;9(2):132–40.
2. Bartnik M, et al. The usefulness of array comparative genomic hybridization in clinical diagnostics
of intellectual disability in children. Dev Period Med. 2014 Jul-Sep;18(3):307-17.
3. Ellison JW, et al. Clinical utility of chromosomal microarray analysis. Pediatrics. 2012
Nov;130(5):e1085-95.
4. Moeschler JB, et al. Comprehensive evaluation of the child with intellectual disability or global
developmental delays. Pediatrics. 2014 Sep;134(3):903-918.
5. Miller DT, et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test
for individuals with developmental disabilities or congenital anomalies. Am J Hum Genet. 2010 May
14;86(5):749-64.