RT Journal Article SR Electronic T1 Identification and characterisation of a small marker chromosome using non-isotopic in situ hybridisation with X and Y specific probes. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 192 OP 194 DO 10.1136/jmg.26.3.192 VO 26 IS 3 A1 Crolla, J A A1 Smith, M A1 Docherty, Z YR 1989 UL http://jmg.bmj.com/content/26/3/192.abstract AB A 13 year old male with mild mental retardation, obesity, and poor secondary sexual differentiation was found to have a 46,X,+,mar karyotype. In situ hybridisation with X and Y specific probes proved the marker to be composed of Y centromeric and short arm material.