Postnatal test for developmental delays approved

The US Food and Drug Administration (FDA) recently approved a unique test that can diagnose developmental delays and intellectual disabilities in babies postnatally.

Using a blood sample, the Affymetrix CytoScan Dx Assay (Affymetrix Inc; Santa Clara, California) detects chromosomal variations linked to Down syndrome, DiGeorge syndrome, and other developmental and intellectual disorders.

The test allows for genome-wide analysis, accelerating an accurate diagnosis and providing the opportunity for earlier intervention and treatment.

Although other genetic tests for detecting conditions such as Down syndrome exist, physicians usually have to order them individually, and they can take several days to develop. The new test should provide information faster and in a more comprehensive way.

The test is not meant for all children, just those who exhibit something unusual, suspicious, or suggestive of an intellectual disability. It is also not to be used for prenatal testing or screening, preimplantation testing or screening, population screening, or for the detection of other problems after birth, such as cancer.

As part of its review for approval, the FDA included a study that compared the performance of the CytoScan Dx Assay to other tests used for identifying chromosomal changes associated with developmental delays. A comparison of test results from 960 blood specimens demonstrated that the CytoScan Dx Assay was better than other tests, including karyotyping and fluorescence in situ hybridization (FISH) chromosomal tests, at detecting certain chromosomal abnormalities.

The manufacturer hopes to make the assay available to US laboratories within the next few months.

According to the National Institutes of Health, about 2% to 3% of children in the United States have an intellectual disability. 

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