A Case of 8p12q11.21 Chimeric Duplication with Normal Pregnancy

Chromosome 8 belongs to the C group of medium-sized sub-centromere chromosomes. Complete trisomy of 8 most often results in aborted embryos or spontaneous abortion. Chimeric trisomy 8 is a rare autosomal abnormality with high phenotypic heterogeneity.

Peripheral blood DNA was extracted by magnetic bead method, and CNV-seq was performed with MGISEQ-2000 sequencer to analyze chromosome copy number variation (CNVs) in chromosome aneuploidy and those with more than 100 Kb.

The test result for the pregnant woman was sseq[GRCh37]8p12q11.21(32608173 48839569)x3 [0.77]chr8:g.32608173 48839569dup. The copy number variant type was pathogenic, and the fragment size was 16.23 Mb.

This study suggests that 8p12q11.21 chimeric duplication carriers may have normal phenotype and reproductive function, which should be considered in genetic counseling, especially prenatal counseling.