[Genetic analysis of a fetus with partial 18p tetraploidy syndrome].

OBJECTIVE: To analyze a fetus with abnormal cardiac ultrasound by using various techniques and explore its genotype-phenotype correlation.

METHODS: Lymphocytes derived from umbilical cord blood sample were subjected to G-banding analysis. Short tandem repeats quantitative fluorescence PCR (STR-QF-PCR) was used for analysis of fetal DNA as an auxiliary test. Low-coverage whole genome sequencing (WGS) was used to detect chromosomal deletion/duplication which exceeded 100 kb in size.

RESULTS: The karyotype of the fetus was 47,XN,+mar. As detected by STR-QF-PCR, the copy number of GATA178F11 locus on chromosome 18 was 4, and the duplicated fragment was derived from the mother. WGS suggested that the fetus to be 46,XN,dup(18p11.21p11.32).seq [GRCh37/hg19](10 001-15 378 887)× 4, with the duplicated fragment spanning approximately 15.38 Mb.

CONCLUSION: The cardiac malformation of the fetus may be attributed to the partial duplication of chromosome 18p. Combined cytogenetic and molecular methods can facilitate prenatal detection of genetic abnormalities.