Test characteristics:
Microarray technologies are used to search for large chromosomal imbalances such as aneuploidies and unbalanced chromosomal rearrangements throughout the human genome. It offers additional opportunities to detect submicroscopic aberrations, or so called Copy Number Variations (CNVs) that are too small to be detected by standard karyotype G-band chromosome banding techniques. These submicroscopic imbalances are also called microdeletions and microduplications. When these CNVs affect specific genomic regions associated with clinical phenotype, they form syndromic complexes. Chromosomal microarray analysis (CMA) has additional diagnostic value, i.e. is capable to make the actual diagnosis in 12-15% of syndromic cases, in which the karyotype is normal.
Reasons for reffering:
The Laboratory of Genomic Diagnostics offers chromosomal microarray analysis with reagents provided by the Ministry of Health. According to Regulation 26, which entered into force on 14 June 2007 and amended on 30 December 2015, microarray analysis with reagents provided by the Ministry of Health can be performed in the following cases:
Indications for microarray prenatal genomic diagnosis:
pregnant women with ultrasound findings or calculated high risk of giving birth to a child with a genetic disease, namely:
multiple fetal malformations and a normal rapid chromosome aneuploidy test result – e.g. spina bifida, anencephaly, lisencephaly, severe abdominal wall defect, and involvement of other organs and systems;
nuchal translucency (NT) ≥3.5 mm;
presence of a chromosomal translocation or marker chromosome detected by karyotyping;
multiple recurrent abortions
intrauterine fetal retardation or fetal death;
increased risk for genetic disease calculated by biochemical screening
presence of chromosomal aberration in previous pregnancies
family history of a specific genetic disease
Indications for chromosomal microarray postnatal genomic diagnostics: examination of children and adults (if necessary relatives) in case of clinical data and suspicion of a genetic disease or predisposition, namely:
• Presence of unexplained delay in neuropsychological development and / or intellectual disability
• Other neurological and neuropsychological problems - autistic stigmas, behavioral problems, speech developmental delay, motor disorders, etc.
Congenital anomalies and malformations affecting various organs and systems - cardiovascular (congenital heart defects), urinary (renal anomalies), nervous (agenesis of the corpus callosum, micro- / macrocephaly), musculoskeletal (joint and bone anomalies, muscle hypotension, etc.), digestive system, etc.
• Presence of facial dysmorphisms (cleft lip and palate, strabismus, hyper- / hypotelorism, ptosis, short filter, pro- / micrognathia, low-lying auricles, etc.)
• Carrying a genetic defect in the parents and an increased risk of inheritance
Interpetation of the results:
The detection of pathogenic microdeletions and / or duplications by this method will reveal the genetic cause of:
observed ultrasound findings and deviations from biochemical screening.
specific neuropsychiatric disorders (epileptic seizures, ID, motor and behavioral disorders) with or without general or facial dysmorphisms.
vague syndromic conditions affecting one or more systems.
This will help in making an accurate genetic diagnosis.
The result includes:
Duplications of clinical significance greater than 1000 Kb and deletions of not less than 500 Kb, affecting genes of functional significance when using a microarray platform with 4x44K resolution.
Duplications of clinical significance greater than 150 Kb, as well as smaller deletions affecting genes of functional significance using microarray platforms with 4x180K, 2x400K and 1x1M resolutions.
The analysis also detects non-pathogenic copy number variations (CNVs), which are described in the Database of Genomic Variants database (http://dgv.tcag.ca/dgv/app/ home? Ref = GRCh37 / hg19
The method cannot detect low levels mosaicism, epigenetic changes, balanced chromosomal rearrangements (inversions and translocations), small insertions / deletions and point mutations, as well as CNVs with a resolution lower than the capabilities of the platform and microarray used; difficulties in detecting polyploidy.
The genetic counselor will interpret and answer all questions about your result.
Method: Chromosomal Microarray analysis / array Comparative Genomic Hybridization (array CGH)
Prenatal diagnostics: The method involves screening of the entire genome in single experiment for microdeletion / duplication changes affecting one or more chromosomes. With the 4x44K platform, genomic aberrations of up to 150 Kbp can be detected.
SurePrint G3 Unrestricted CGH 4x44K, ISCA v2: the platform contains immobilized 44,000 60-mer oligonucleotide samples, with a sample density of 25 Kb (11 Kb in regions with Ref Seq genes) with greater coverage in regions containing known genes, promoter and telomeric regions.
Postnatal diagnostics:
The method involves screening the entire genome in one experiment to look for microdeletion / duplication changes affecting one or more chromosomes. The 4x180K platform analyzes a portion of the genome covering approximately 180 Kb of DNA, making the method with higher resolution than standard cytogenetic techniques.
SurePrint G3 Unrestricted CGH 4x180K, ISCA v2: the platform contains immobilized 180,000 60-dimensional oligonucleotide samples, with a sample density of 13 Kb (11 Kb in areas with Ref Seq genes) with greater coverage in areas containing known genes, promoter and telomeric regions.
The laboratory also offers confirmatory analysis / segregation of aberrations detected by microаrray analysis in cases where deletions / duplications of rearrangements are located in specific genomic regions, offered by the MLPA test (Test № 133).
In case the current test does not lead to the detection of large deletions / duplications, and the clinical phenotype and new medical studies suggest the presence of microdeletion / duplication regions, we recommend microarray analysis at the request of the client - with SurePrint G3 Unrestricted CGH 2x400K or 1x1M (Test № 145, 146).
In case that the present test does not elucidate the genetic causes of the disease, we recommend performing next generation sequencing and analysis for mutations in a panel of disease-related genes (Test № 152, 153, 154).
What does the test include?
Isolation of DNA from prenatal probe (chorionic villi, amniotic cells, fetal part, umbilical cord, placental villi) or postnatal probe (blood) and storage of isolated DNA sample
Chromosomal Microarray analysis / array Comparative Genomic Hybridization (array CGH) to detect pathogenic copy number variations.
Software processing of the microarray slide and data analysis. For each patient, data on specific genomic regions associated with previously known chromosomal diseases are analyzed, as well as in accordance with the guiding diagnosis.
Forming a written result from the genetic test.
Diagnostic interpretation of results and genetic counseling.
Biological material: chorionic villi, amniotic cells, fetal part, umbilical cord, placental hairs, blood or DNA
For more information, please read "Biological Sample Requirements and Transport Information" carefully.
