[Genetic analysis of a fetus with partial 18p deletion]

To carry out prenatal diagnosis for a fetus with partial 18p deletion detected by non-invasive prenatal testing (NIPT).

Peripheral blood and amniotic fluid samples of the pregnant woman and her husband were subjected to G-banded chromosomal karyotyping and more accurate chromosomal microarray analysis (CMA). The deletion sites were verified by fluorescence in situ hybridization (FISH) using centromeric probe Cep11 Aqua and telomeric probes Tel11q SO and Tel18 SG.

The karyotype of the fetus was determined as 46,XN,del(18)(p11.3). CMA has detected a 6.66 Mb deletion at 18p11.32-p11.31 (136 226-6 796 178). FISH confirmed the presence of a partial deletion at 18p. The mother was found to harbor the same deletion by chromosomal karyotyping as well as CMA analysis. No abnormality was found with the husband.

Although the fetus and its mother have both carried the same 18p deletion, no clinical manifestation was detected in the mother, which may be attributed to a low penetrance of the disorder. The fetus had died at 33 weeks of gestation with unknown cause.