genesThe US Food and Drug Administration (FDA) has approved for marketing a post-natal test to help diagnose developmental delays and learning disabilities in children, which could help them to access support more quickly.

The test, Affymetrix CytoScan Dx Assay, which is manufactured by Affymetrix, Inc, can detect chromosomal variations that may be responsible for a child’s developmental delay or intellectual disability. Based on a blood sample, the test analyses the entire genome at once and can detect large and small chromosomal changes.

As part of the reviewing process, the FDA undertook a study that compared the performance of CytoScan Dx Assay to tests commonly used for detecting chromosomal variations associated with a developmental delay or intellectual disability. A comparison of test results from 960 blood specimens showed the CytoScan Dx had improved ability over commonly used tests, including karyotyping and FISH chromosomal tests, to detect certain chromosomal abnormalities.

“This new tool may help in the identification of possible causes of a child’s developmental delay or intellectual disability, allowing health care providers and parents to intervene with appropriate care and support for the child,” said Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Center for Devices and Radiological Health. 

The FDA emphasised that test results should only be used in conjunction with other clinical and diagnostic findings, consistent with professional standards of practice, including confirmation by alternative methods, evaluation of parental samples, clinical genetic evaluation, and counselling as appropriate. 

Beverley Dawkins, special adviser for Mencap, welcomed the move: “This is a positive step towards getting an earlier diagnosis of genetic conditions that may be associated with having a learning disability. Earlier diagnosis can help families get vital support and interventions as soon as possible. 

“However, the presence of genetic differences does not tell us much about the degree of learning disability than an individual child may experience, as such tests should only ever be used as part of the assessment of a child’s needs.”