Pure and complete 12p trisomy due to a maternal centric fission of chromosome 12

Abstract

Pure and complete 12p trisomy are rare. Here, we report on a unique patient with trisomy 12p syndrome due to centric fission of maternal chromosome 12. Conventional cytogenetic and fluorescence in situ hybridization (FISH) techniques revealed the proposita's karyotype to be 47,XX,+fis(12)(p10)mat whereas the maternal one was 47,XX,-12,+fis(12)(p10),+fis(12) (q10). This is the first report on centric fission of chromosome 12 leading to stable telocentrics, each with a fully functional centromere. Our observation shows that the centric fission of chromosome 12 can be a new mechanism for generation of a partial centromere and trisomy 12p syndrome.