[Analysis of four fetuses with de novo chromosomal rearrangments using single nucleotide polymorphism microarray chips].

OBJECTIVE

To assess the value of single nucleotide polymophism (SNP) microarray for delineation of de novo chromosomal rearrangements detected upon prenatal diagnosis.

METHODS

SNP microarray analysis was carried out for 4 fetuses with de novo sSMCs or balanced reciprocal translocations. Genomic DNA was extracted from cord blood samples, and amplified, tagged and hybridized following the manufacturer's protocol. Data were collected and analyzed.

RESULTS

No pathogenic CNVs were detected in fetus A, whose sSMCs was verified to be heterochromatin. Fetus B, who had a de novo mosaic sSMCs, was found to have a 9 Mb duplication in 4p12-q13 which is associated with speech delay and mental retardation. No pathogenic CNVs were detected in fetus C who has 2 translocation chromosomes inherited from its mother and 2 chromosomes derived from a de novo translocation. Fetus D, who had a de novo "balanced" reciprocal translocation, was found to have a 25 Mb duplication in 1q25 and a 17 Mb deletion in 9p22. Cases A and C had normal physical and mental evaluation after birth.

CONCLUSION

For its ability to detect cryptic imbalance in de novo sSMCs or balanced reciprocal translocations, SNP-array has provided a powerful aid to conventional karyotype analysis during prenatal diagnosis.