"Consensus Statement: The microarray is the first clinical diagnostic tool for individuals with developmental delay or congenital abnormalities [...]. The existing evidence supports the use of microarrays in place of the G band karyotyping as the first diagnostic test in patients with intellectual disabilities, autistic spectrum disorders or congenital malformations" (Miller et al., AJHG, 2010).
qChip Post® is an oligonucleotide microarray based on a propietary design, specifically developed for use in clinical routines, and that is constantly evolving and adapting to new knowledge that is generated.
It can detect 250+ different copy number alterations related to human disease. The combination of global coverage and affordable price, make it ideal for routine analysis of patients with idiopathic developmental delay, autism and congenital anomalies. The design covers with high resolution pericentromeric and subtelomeric regions, as well as regions associated to syndromes caused by recurrent genomic alterations; in addition, it contains probes that interrogate the rest of the genome at an effective average resolution of 300kb.
This design is suitable for
- Detecting and characterizing submicroscopic copy number aberrations.
- Characterizing copy number imbalances previously identified with the study of the karyotype (apparently balanced translocations, additions, derivative chromosomes, etc)
- Identifying and characterizing small supernumerary marker chromosomes (sSMCs) containing euchromatin (Tsuchiya 2008 Very Cytog; Sheth 2011 EJMG)
For what cases is it indicated?
- patients with idiopathic mental retardation, autism, growth retardation, and/or multiple congenital anomalies.
- patients with abnormal karyotype that require molecular characterization.
- Microarray composed of ~60,000 oligonucleotide probes.
- Interrogates 250+ known genetic disorders (see link for a detailed list of interrogated regions).
- Average coverage in clinically relevant regions: 1 probe/10Kb.
- Average coverage in the rest of the genome: 1 probe/125Kb.
It is important to remember that
- Sometimes, the completion of the study for proper genetic counseling may require additional studies (FISH, for example), both in the index case and in samples from other relatives (parents, usually).
Higher resolution alternatives
Where deemed appropriate a more accurate analysis, qGenomics offers higher resolution microarrays allowing analysis of changes in copy number affecting smaller genomic regions.
- qChip 4x180K. ~ 180,000 oligonucleotide probes evenly distributed throughout the genome, one probe every 17Kb on average (~ 50-60 Kb practical resolution).
- qChip 2x400K. ~ 400,000 oligonucleotide probes evenly distributed throughout the genome, a probe per 7.5Kb, which represents a resolution of approximately 30 to 40KB.
- qChip 1M. ~ 1,000,000 oligonucleotide probes evenly distributed throughout the human genome, with an average 3Kb each probe, which represents a practical resolution of about 10 to 15KB. It enables maximum detection capacity of segmental aneuploidy in cases of 'apparently balanced' translocations related with intellectual disability.