[Clinical and genetic analysis of a rare case with mosaic partial trisomy 5p syndrome].

To determine the size and origin of a small supernumerary marker chromosome (sSMC) identified in a patient featuring developmental retardation.High-throughput sequencing for copy number variation (CNV-seq) was carried out to delineate the sSMC identified upon G-banded chromosomal karyotyping. The genotype-phenotype correlation was explored by database retrieval and literature analysis.The patient was found to have a karyotype of mos 47,XX,+mar[36]/46,XX[23]. CNV-seq has identified a 18 Mb duplication at 5p14.1-p12 (hg19: 27,399,261-46,083,784)x2.6 with a mosaicism rate of approximately 60%.Patients with mosaic partial trisomy 5p may have extensive clinical manifestations, and the ratio of trisomy 5p cells is correlated with clinical severity of this syndrome.