title: Methylation-specific PCR allows for fast diagnosis of X chromosome disomy and reveals skewed inactivation of the X chromosome in men with Klinefelter syndrome.
abstract: Klinefelter syndrome (KS) remains the most common, yet often undiagnosed,  chromosomal aberration in men. Early diagnosis and treatment can improve the  health of patients with KS. The aim of this study was to evaluate the  inactivation pattern of supernumerary X chromosomes. The secondary aim was to  design a reliable and cost-effective molecular test for detection of X  chromosome disomy. Methylation-specific polymerase chain reaction (M-PCR),  with primers for familial mental retardation (FMR1) and X chromosome  inactive-specific transcript (XIST) genes, was used to detect the presence of  X chromosome disomy in men. Seventeen fertile males, 12 females, and 35 males  with KS (28 with 47,XXY karyotype, and 7 with 47,XXY/46,XY mosaics) were  included in the study. Results of the karyotype were compared with the results  of semiquantitative M-PCR. Inactivation of X chromosomes was measured by  XIST/FMR-1 methylation ratio. Differences in the methylation patterns of FMR1  and XIST genes between 46,XY men and men with X chromosome disomy allowed for  rapid detection of the presence of an additional X chromosome, achieving 100%  sensitivity and specificity using M-PCR. The methylated:unmethylated FMR1  amplicon ratio allowed the detection of 1 additional X chromosome per 100  normal XY cells (1% of XX/XY mosaicism). In our series, 50% of 47,XXY men  showed skewed inactivation of the X chromosome. Men with KS can have  incomplete inactivation of supernumerary X chromosomes. M-PCR is a sensitive,  specific, fast, and relatively inexpensive test for the diagnosis of X  chromosome disomy.
authors.affiliation: Department of Urology, Weill Cornell Medical College, 525 E 68th St, Box 580, New York, NY 10021, USA. mehtagrossberg@gmail.com
authors.forename: Akanksha
authors.initials: A
authors.lastname: Mehta
authors.forename: Matthew
authors.initials: M
authors.lastname: Malek-Jones
authors.forename: Alexander
authors.initials: A
authors.lastname: Bolyakov
authors.forename: Anna
authors.initials: A
authors.lastname: Mielnik
authors.forename: Peter N
authors.initials: PN
authors.lastname: Schlegel
authors.forename: Darius A
authors.initials: DA
authors.lastname: Paduch
mesh_terms: D041321:Chromosomes, Human, X; D019175:DNA Methylation; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics*; D005820:Genetic Testing / Q000191:economics / Q000379:methods*; D006801:Humans; D007621:Karyotyping; D007713:Klinefelter Syndrome / Q000175:diagnosis* / Q000235:genetics; D008297:Male; D016133:Polymerase Chain Reaction / Q000191:economics / Q000379:methods*; D011237:Predictive Value of Tests; D062085:RNA, Long Noncoding / Q000235:genetics*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D049951:X Chromosome Inactivation
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; D062085:RNA, Long Noncoding; C497683:FMR1 protein, human; C077885:XIST non-coding RNA