RESUMO
<p><b>OBJECTIVE</b>To investigate the origin of a rare supernumerary chromosome in a patient with premature ovarian failure (POF), and to explore the relationship between this abnormal karyotype and pathogenesis of POF.</p><p><b>METHODS</b>GTG banding karyotyping, Q-banding and fluorescence in situ hybridization (FISH) were employed for the investigation.</p><p><b>RESULTS</b>The extra chromosome was identified as i(Y)(q10) by FISH with a panel of sex chromosome probes. The patient's karyotype was described as: 47,XX,+ ish mar i(Y)(q10) (DXZ1-, SRY-, DYZ3+, DYZ1++, wcpY+).</p><p><b>CONCLUSION</b>Co-occurrence of the supernumerary i(Y)(q10) with a female kryotype is extremely rare. This supernumerary chromosome may cause failure of X chromosomes synapsis during pachytene of meiosis I, which may trigger apoptosis of many oocytes and result in POF of the patient. Q-banding, FISH and multiple probes have been critical for accurate diagnosis of the unknown chromosome.</p>