Abstract
BackgroundThe majority of small supernumerary marker chromosome cases arise de novo and their frequency in newborns is 0.04%. We report on a girl with developmental delay and dysmorphic features with a non-mosaic de novo sSMC that originated from the pericentric region of q arm in chromosome 17.Case presentationThe girl presented with developmental delay, speech delay, myopia, mild muscle hypotonia, hypoplasia of orbicular muscle, poor concentration, and hyperactivity. Main dysmorphic features included: round face, microstomia, small chin, down-slanting palpebral fissures and small lobules of both ears. At present, her developmental abilities are still delayed for her chronological age but she is making evident progress with speech.A postnatal array comparative genomic hybridization showed a 2.31 Mb genomic gain indicating microduplication derived from pericentric regions q11.1 and q11.2 of chromosome 17. Additional conventional cytogenetic analysis from peripheral blood characterized the karyotype as 47,XX,+mar in a non-mosaic form. The location of microduplication was confirmed with fluorescence in situ hybridization.ConclusionThe proband’s microduplication encompassed approximately 40 annotated genes, several of which have been associated with phenotypic characteristics of the proband. This is the first report of sSMC 17 including this particular chromosomal region in non-mosaic form.
Highlights
The majority of small supernumerary marker chromosome cases arise de novo and their frequency in newborns is 0.04%
A postnatal Array comparative genomic hybridization (aCGH) showed a microduplication of 2.31 ± 0.06 Mb encompassing pericentric regions q11.1 and q11.2 derived from chromosome 17 (arr[hg19] 17q11.1q11.2(25,403,446-27,716,930)x3) (Fig. 1)
We found a de novo Small supernumerary marker chromosomes (sSMC) derived from chromosome region 17q11.1q11.2 using aCGH and fluorescence in situ hybridization (FISH) in a girl with developmental delay, speech delay, dysmorphic features and hyperactivity
Summary
The majority of small supernumerary marker chromosome cases arise de novo and their frequency in newborns is 0.04%. We report on a girl with developmental delay and dysmorphic features with a non-mosaic de novo sSMC that originated from the pericentric region of q arm in chromosome 17. Conclusion: The proband’s microduplication encompassed approximately 40 annotated genes, several of which have been associated with phenotypic characteristics of the proband This is the first report of sSMC 17 including this particular chromosomal region in non-mosaic form. A de novo sSMC derived from a pericentric region of the q arm in chromosome 17 in a centric minute shape is described It was identified postnatally and confirmed with fluorescence in situ hybridization (FISH). To our knowledge, this is the first report of this particular sSMC 17 in non-mosaic form
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