title: Molecular cytogenetic characterization of two Turner syndrome patients with mosaic ring X chromosome.
abstract: OBJECTIVE
  In the present study, we reported two cases of TS with mosaic ring X chromosome showing common clinical characteristics of TS like growth retardation and ovarian dysfunction. The purpose of the present study was to cytogenetically characterize both cases.
  
  
  METHODS
  Whole blood culture and G-banding were performed for karyotyping the cases following standard protocol. Origin of the ring chromosome and degree of mosaicism were further determined by fluorescence in situ hybridization (FISH). Breakpoints and loss of genetic material in formation of different ring X chromosomes r (X) in cases were determined with the help of cytogenetic microarray.
  
  
  RESULTS
  Cases 1 and 2 with ring chromosome were cytogenetically characterized as 45, X [114]/46Xr (X) (p22.11q21.32) [116] and 45, X [170]/46, Xr (X) (p22.2q21.33) [92], respectively. Sizes of these ring X chromosomes were found to be ~75 and ~95 Mb in cases 1 and 2, respectively, using visual estimation as part of cytogenetic observation. In both cases, we observed breakpoints on Xq chromosome were within relatively narrow region between Xq21.33 and Xq22.1 compared to regions in previously reported cases associated with ovarian dysgenesis.
  
  
  CONCLUSIONS
  Our observation agrees with the fact that despite of large heterogeneity, severity of the cases with intact X-inactive specific transcript (XIST) is dependent on degree of mosaicism and extent of Xq deletion having crucial genes involved directly or indirectly in various physiological involving ovarian cyclicity.
authors.affiliation: Centre for Genetic Disorders, Institute of Science, Banaras Hindu University, Varanasi, India.
authors.forename: Pooja
authors.initials: P
authors.lastname: Chauhan
authors.affiliation: Centre for Genetic Disorders, Institute of Science, Banaras Hindu University, Varanasi, India.
authors.forename: Sushil Kumar
authors.initials: SK
authors.lastname: Jaiswal
authors.affiliation: Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
authors.forename: Anjali Rani
authors.initials: AR
authors.lastname: Lakhotia
authors.affiliation: Centre for Genetic Disorders, Institute of Science, Banaras Hindu University, Varanasi, India. akrai10@gmail.com.
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Rai
mesh_terms: D000328:Adult; D002871:Chromosome Banding; D002872:Chromosome Deletion; D041321:Chromosomes, Human, X / Q000235:genetics*; D003582:Cytogenetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008875:Middle Aged; D009030:Mosaicism; D010049:Ovarian Diseases / Q000235:genetics* / Q000473:pathology; D012303:Ring Chromosomes; D014424:Turner Syndrome / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology
keywords: Cytogenetic microarray; Fluorescence in situ hybridization (FISH); Ovarian dysfunction; Ring X chromosome; Turner syndrome