A case report of a fetus with mosaic autosomal variegated aneuploidies and literature review

Mosaic variegated aneuploidy (MVA) is a recessive condition characterized by mosaic aneuploidies, predominantly trisomies and monosomies, involving multiple chromosomes and tissues. The phenotype of MVA syndrome includes severe microcephaly and growth deficiency, central nervous system anomalies, mental retardation, mild physical anomalies, and predisposition to cancer. We report a case of true fetal mosaicism for variegated aneuploidies detected in amniotic fluid cells. A 33-year-old primigravida woman at 5 weeks 1 day of gestation was referred to our tertiary hospital because of a high-risk pregnancy associated with IgA nephropathy. In a quadruple screening test performed at the 15^th week of gestation, alpha fetoprotein was 73.4 IU/mL (2.792 MoM), suggesting that she was at high risk of neural tube defect. Following amniocentesis performed at the 17 weeks' gestation, chromosome examination of amniocyte culture showed premature chromatic separation in 63% of the metaphases (58/92) and a high frequency of gain and loss of chromosomes. Repeat amniocentesis at 21 weeks' gestation consistently showed the presence of multiple mosaic autosomal variegated aneuploidies. Ultrasonography at 21 weeks' gestation revealed relatively small head circumference for gestational age (<3%) and vermis defect, suggesting that the fetus would have microcephaly and Dandy-Walker malformation. Cytogenetic analysis with peripheral blood of the parents showed normal karyotype. In summary, we hereby report the cytogenetic analysis and prenatal findings of MVA.