<p>Abstract</p> <p>Background</p> <p>Small supernumerary marker chromosomes (sSMC) can be present in numerically abnormal karyotypes like in a 'Turner-syndrome karyotype' mos 45,X/46,X,+mar.</p> <p>Results</p> <p>Here we report the first case of an sSMC found in Turner syndrome karyotypes (sSMC<sup>T</sup>) derived from chromosome 14 in a Turner syndrome patient. According to cytogenetic and molecular cytogenetic characterization the karyotype was 46,X,+del(14)(q11.1). The present case is the third Turner syndrome case with an sSMC<sup>T </sup>not derived from the X- or the Y-chromosome.</p> <p>Conclusion</p> <p>More comprehensive characterization of such sSMC<sup>T </sup>might identify them to be more frequent than only ~0.6% in Turner syndrome cases according to available data.</p
