FirstStepDx PLUS chromosomal microarray analysis (CMA) is a genetic test designed to identify genomic deletions and duplications, known as copy number variants, which are common causes of:
CMA can also detect absence of heterozygosity (AOH), a unique finding associated with an increased risk for certain types of genetic conditions. In some cases, AOH is a result of uniparental disomy (UPD), which can be related to imprinting disorders.
Bionano Laboratories offers unlimited clinical support to patients and providers through access to our genetic counselors who can discuss testing capabilities, strategy, informed consent, and results.
Providers can call our genetic counselors at:
Identification, Evaluation, and Management of Children With Autism Spectrum Disorder. 2020. PMID: 31843864
Pathogenic Yield of Genetic Testing in Autism Spectrum Disorder. 2020. PMID: 32938777
Comprehensive evaluation of the child with intellectual disability or global developmental delays. 2014. PMID: 25157020
Clinical utility of chromosomal microarray analysis. 2012. PMID: 23071206
Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. 2010. PMID: 20466091
Array-based technology and recommendations for utilization in medical genetics practice for detection of chromosomal abnormalities. 2010. PMID : 20962661
Clinical genetic testing for patients with autism spectrum disorders. 2010. PMID : 20231187
Evidence report : Genetic and metabolic testing on children with global developmental delay : report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society. 2011. PMID : 21956720
Practice parameter for the assessment and treatment of children and adolescents with autism spectrum disorder. 2014. PMID : 24472258
DNA is prepared according to Illumina specifications for the Infinium Global Screening Array v2 (GSA) custom chip.
When applicable, Bionano may complete confirmatory testing of a CNV prior to reporting. When restricted to a single chromosome, AOH is reported when greater than 8-15 megabases (Mb; dependent upon chromosomal location and likelihood of imprinting disorder). AOH is also reported when the total proportion across all autosomes is greater than 3% (only autosomal AOH greater than 3 Mb are considered for this estimate).
CMA can detect conditions caused by genomic duplications and deletions, such as 22q11.2 deletion syndrome and 15q11.2 deletion syndrome. Identifying a specific genetic etiology for an individual’s presentation may help determine more appropriate and tailored medical management, provide information about the course of the disease, and demonstrate a need for testing at-risk relatives.
Patients who have had genetic tests, particularly a chromosomal microarray test like the FirstStepDx PLUS, but did not find a genetic cause underlying their condition, are candidates for the NextStepDx PLUS whole exome sequencing test. Additionally, an evaluation or consultation by a medical geneticist (physician who specializes in genetic conditions) or genetic counselor could be useful to help determine a follow-up testing strategy.
The underlying genetic cause for an individual’s clinical features can be due to many different types of genetic variants. While FirstStepDx PLUS can identify chromosomal deletions (missing genetic material) and duplications (extra genetic material), NextStepDx PLUS looks for single nucleotide variants that are much smaller and can’t be detected by FirstStepDx PLUS.
If we consider our genetic material to be like an instructional manual, FirstStepDx PLUS looks for missing or duplicated chapters or pages while NextStepDx PLUS looks for misspellings within a single word. Neither test can do the other’s job. Instead, they complement each other. If FirstStepDx PLUS does not find an underlying genetic cause for your patient’s clinical features, performing NextStepDx PLUS is a way to look at your patient’s genetic information in a totally different way.