2022-02-152022-02-152012-12Gülten, T. vd. (2012). "Another small supernumerary marker chromosome derived from chromosome 9 in a Klinefelter patient". West Indian Medical Journal, 61(9), 924-927.0043-3144https://doi.org/10.7727/wimj.2012.027https://www.mona.uwi.edu/fms/wimj/article/501http://hdl.handle.net/11452/24481Marker chromosomes are very rare in Klinefelter patients and phenotypic findings are related to the affected chromosomal region. The phenotypic effects of small supernumerary marker chromosomes (sSMC) range from multiple malformations/mental retardation to no effect (le a normal phenotype). This wide spectrum of phenotypes is due to the origin, structure and gene content of the marker chromosome. The first Klinefelter case with sSMC 9 was published by Liehr et al in 2005. The present case was referred for chromosomal analysis because of dysmorphic features, speech delay and mild mental retardation. Conventional cytogenetic analysis revealed the 47 XXY karyotype in 17 metaphases and the 48 XXY + marker karyotype in eight metaphases. Fluorescence in situ hybridization (FISH) analysis to identify the marker chromosome was performed using the LSI p16 (9p21) Spectrum Orange/CEP 9 SpectrumGreen Probe (Vysis CDKN2A/CEP 9 FISH Probe) and partial trisomy 9 mosaicism was confirmed in this patient. To our knowledge, this is the second case of Klinefelter syndrome with a small supernumerary marker chromosome derived from chromosome 9.eninfo:eu-repo/semantics/closedAccessGeneral & internal medicineFluorescence in situ hybridization (fish) analysisKlinefelter's syndromeSmall supernumerary marker chromosomeChild, preschoolChromosome disordersChromosomes, human, pair 9Genetic markersHumansIn situ hybridization, fluorescenceKaryotypingKlinefelter syndromeMaleMosaicismPhenotypeTrisomyUniparental disomyArticle0003224243000162-s2.0-8488677820092492761924020236Medicine, general & internalChromosome 15; Karyotype; MosaicismArticleCase reportChildChromosome 9Chromosome analysisClinical articleFluorescence in situ hybridizationHumanHuman cellKaryotype 47,XXYKlinefelter syndromeMaleMental deficiencyMetaphasePartial trisomy 9Patient referralPreschool childSpeech delaySupernumerary chromosomeTeratologyArticleChromosome disorderGenetic markerGeneticsKaryotypingKlinefelter syndromeMosaicismPhenotypetrisomyUniparental disomy