Prenatal genetic diagnosis in a fetus with isolated partial trisomy 18p syndrome and literature review

Abstract

Objective To investigate the characteristics of prenatal diagnosis of isolated partial trisomy 18p syndrome. Methods Traditional chromosome karyotype and chromosome microarray analysis (CMA) was used to process karyotyping and genomic copy number variation analysis. Results The result of fetal amniotic fluid chromosome karyotype was 46,XY,der(18). Both parents had normal chromosome karyotype with 46,XY and 46,XX, respectively. The fetal CMA test result was arr [hg19]18p11.31p11.21 (3,521,718-15,099,116) ×3. That is to say, there was 11.58 Mb fragment duplication derived from the chromosome 18 short arm p11.31p11.21 region. CMA test results were negative for both parents, suggesting that the chromosome 18 structure variation of the fetus was de novo. Conclusions A rare novel isolated partial trisomy 18p variation was detected in a fetus whose mother with abnormal pregnancy history. This is world’s infrequent prenatal case report of isolated partial trisomy 18p syndrome. Combined with traditional chromosome karyotype and CMA, gene chip technology has an important clinical value in the prevention of fetal birth defects of abnormal pregnancy history family in prenatal diagnosis. Key words: Abnormal pregnancy; Prenatal dignosis; Isolated partial trisomy 18p syndrome; Chromosome microarray analysis (CMA); Chromosome microdeletion and microduplication syndrome