Our IDNext panel includes 140 genes associated with intellectual disability. This test includes gene sequencing and deletion/duplication analysis. FMR1 repeat expansion testing is not included in this test but can be ordered concurrently. Genomic deoxyribonucleic acid (gDNA) is isolated from the patient’s specimen using a standardized kit and quantified. Sequence enrichment of the targeted coding exons and adjacent intronic nucleotides is carried out by a bait-capture methodology using long biotinylated oligonucleotide probes, followed by polymerase chain reaction (PCR) and next generation sequencing (NGS).
Sanger sequencing is performed for any regions missing, or with insufficient read depth coverage for reliable heterozygous variant detection. Potentially homozygous variants, variants in regions complicated by pseudogene interference, and variant calls not satisfying depth of coverage and variant allele frequency quality thresholds are verified by Sanger sequencing. This assay targets all coding domains, and well into the flanking 5’ and 3’ ends of all the introns and untranslated regions. Gross deletion/duplication analysis for available genes is performed using a custom pipeline based on read-depth from NGS data and/or targeted chromosomal microarray with confirmatory MLPA when applicable.
1. Larson SL, et al. Prevalence of mental retardation and/or developmental disabilities: Analysis of the 1994/1995 NHIS-D. MR/DD Data Brief. Minneapolis, MN: Institute on Community Integration, University of Minnesota. 2000.
2. 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):749-764.
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