Abstract: Objective　To explore the clinical features, cytogenetic and molecular genetics characteristics of trisomy 12p in neonates. Method　The clinical data were reviewed in a neonate with trisomy 12p confirmed by routine G-banding chromosome karyotype analysis, high throughput sequencing chromosome copy number variation analysis (CNV) and lymphocyte interphase fluorescence in situ hybridization (FISH). Results　The chromosome karyotype in peripheral blood of the neonate was 47,XX,+mar, and the karyotypes of her parents were normal. CNV detected a regional duplication of 12 p13.33-p11.1 (16000134860000) with a fragment size of 34.7 Mb. Peripheral blood lymphocyte interphase FISH showed that there were 3 signals in the short arm of chromosome 12 in all interphase nuclei of the neonate, and no chimera existed. It was finally confirmed to be trisomy 12p. Conclusion　The combination of clinical features, peripheral blood karyotype analysis, CNV and FISH techniques can effectively confirm the diaganosis of trisomy 12p .

Key words: trisomy12p;　karyotype analysis technique;　newborn