Shares of Affymetrix (UNKNOWN:AFFX.DL) rose by 2.4%, or $0.22, in after-hours trading following a nod from the Food and Drug Administration on Friday. In a press release, the FDA said it had given the green light for the company to market its CytoScan Dx Assay, a post-natal test that aids in the diagnosis of developmental and intellectual difficulties in infants.

The test works by detecting chromosomal variations, the presence of which could indicate such problems.

The approval was effected through the FDA's de novo process, a system used for certain devices that the FDA determines carry low to moderate risk.

The news comes just over one week after Affymetrix released its preliminary Q4 and fiscal 2013 revenue figures. For the quarter, the company expects total revenue of roughly $91 million, while for the full year that line item is anticipated to come in at $329 million.

The company is scheduled to release its official figures for the quarter and year on Feb. 5.