High-level mosaic trisomy 9 at amniocentesis in a pregnancy with a positive non-invasive prenatal testing result for trisomy 9, intrauterine growth restriction, fetal structural abnormality, cytogenetic discrepancy between cultured amniocytes and uncultured amniocytes, maternal uniparental disomy 9, a normal karyotype at birth, perinatal progressive decrease of the trisomy 9 cell line, concomitant heterozygous mutations of POLG2 and DCC and an adverse fetal outcome.