De novo 16p13.11 microdeletion identified by high-resolution array CGH in a fetus with increased nuchal translucency

We investigated the application of high-resolution microarray-based comparative genomic hybridisation (array CGH) on a fetus showing increased nuchal translucency (NT).

Case study.

Tertiary referral obstetrics unit.

Pregnant woman attended the antenatal clinic.

Conventional karyotyping and genetic test was carried out for the alpha-globin gene. High-resolution array CGH using the high-density 244K Agilent microarray was performed on fetal blood sample by cordocentesis to investigate the possibility of any genomic imbalance.

Detection of chromosomal abnormality.

Karyotyping analysis showed 46,XY. Molecular genetic diagnosis confirms the fetus has Hb-H constant spring disease but cannot explain the increased NT to 3.2 mm. Array CGH analysis discovered a 1.32-Mb microdeletion on chromosome 16p13.11. Deletion at 16p13.11 has been implicated to predispose to autism and/or mental retardation. Baby was delivered at 40 weeks of gestation, and follow up was carried out at 3 months of age without sign of mental retardation/developmental delay.

This case study demonstrated that array CGH can accurately calibrate the size and identify de novo interstitial chromosome imbalances. However, the presence of chromosome copy variants with unknown clinical significance currently limits its wider scale application in prenatal diagnosis and needs further investigations.