An unusual cause for Coffin-Lowry syndrome: Three brothers with a novel microduplication in RPS6KA3.
Valerie J CastelluccioFrancesco VetriniTy LynnesJulie JonesLynda HollowayAlyce BelonisAmy M BremanBrett H GrahamKatherine SappTheodore WilsonCharles E SchwartzVictoria M PrattDavid D WeaverPublished in: American journal of medical genetics. Part A (2019)
Coffin-Lowry syndrome (CLS) is a rare X-linked disorder characterized by moderate to severe intellectual disability, hypotonia, craniofacial features, tapering digits, short stature, and skeletal deformities. Using whole exome sequencing and high-resolution targeted comparative genomic hybridization array analysis, we identified a novel microduplication encompassing exons five through nine of RPS6KA3 in three full brothers. Each brother presented with intellectual disability and clinical and radiographic features consistent with CLS. qRT-PCR analyses performed on mRNA from the peripheral blood of the three siblings revealed a marked reduction of RPS6KA3 levels suggesting a loss-of-function mechanism. PCR analysis of the patients' cDNA detected a band greater than expected for an exon 4-10 amplicon, suggesting this was likely a direct duplication that lies between exons 4 through 10, which was later confirmed by Sanger sequencing. This microduplication is only the third intragenic duplication of RPS6KA3, and the second and smallest reported to date thought to cause CLS. Our study further supports the clinical utility of methods such as next-generation sequencing and high-resolution genomic arrays to detect small intragenic duplications. These methods, coupled with expression studies and cDNA structural analysis have the capacity to confirm the diagnosis of CLS in these rare cases.
Keyphrases
- intellectual disability
- high resolution
- autism spectrum disorder
- peripheral blood
- copy number
- end stage renal disease
- single cell
- ejection fraction
- newly diagnosed
- poor prognosis
- mass spectrometry
- prognostic factors
- case report
- binding protein
- patient reported outcomes
- high intensity
- single molecule
- tandem mass spectrometry
- gene expression
- cancer therapy
- high speed