Detection of DiGeorge syndrome (microdeletion 22q11.2)

The DiGeorge syndrome is the second most common cause of a delay in fetal development and of severe congenital heart defects [1, 2]. The postnatal prevalence is about 1: 4000 to 1: 6000 [2]. Recent data show that the prenatal prevalence can reach up to 1: 1000 [3].

The DiGeorge syndrome is caused by a submicroscopic deletion in chromosome 22. In most cases, the size of the deletion is about 3 megabases (MB), but in about 10-15% of cases it can be even smaller (1.5 MB or less.)

With the Harmony® Test it is now possible to detect and largely exclude the DiGeorge syndrome in the unborn child from maternal blood.

A first validation study showed that the Harmony® Test also detects 22q11.2 microdeletions of less than 3 MB [4].

In singleton pregnancies, the option of screening for the microdeletion 22q11.2 can be added to any of the existing Harmony® Test panels.

As each additional test option increases the overall false-positive rate of a non-invasive prenatal test [5], we recommend requesting the „DiGeorge syndrome“ test option only in pregnancies with an increased risk for this microdeletion.

You can order our latest test requisition form with the test option for DiGeorge syndrome here.

 

References:

[1]            Bassett et al. J Pediatr. 2011 Aug;1 59(2): 332-9

[2]           McDonald-McGinn et al. GeneReviews 1999 Sep 23

[3]           Grati FR et al. Prenat Diagn 2015; 35: 801–809

[4]           Schmid M et al. Fetal Diagn Ther 2017 Nov 8, E-pub ahead of print

[5]           Stumm M, Schröer A. Gynäkologe 2018; 51: 24-31