The US Food and Drug Administration has authorized for marketing the Affymetrix CytoScan Dx Assay, which can detect chromosomal variations that may be responsible for a child’s developmental delay or intellectual disability. Based on a blood sample, the test can analyse the entire genome at one time and detect large and small chromosomal changes.

According to the National Institutes of Health and the American Academy of Paediatrics, two to three per cent of children in the United States have some form of intellectual disability. Many intellectual and developmental disabilities, such as Down syndrome and DiGeorge syndrome, are associated with chromosomal variations.

“This new tool may help in the identification of possible causes of a child’s developmental delay or intellectual disability, allowing healthcare providers and parents to intervene with appropriate care and support for the child,” said Alberto Gutierrez, director of the Office of In Vitro Diagnostics and Radiological Health in the FDA’s Centre for Devices and Radiological Health. “The FDA’s review of the test provides clinical laboratories with information about the expected performance of the device and the quality of the results.”

The FDA reviewed the Affymetrix CytoScan Dx Assay through its de novo classification process, a regulatory pathway for some novel low-moderate-risk medical devices.

For the de novo petition, the FDA’s review of the CytoScan Dx Assay included an analytical evaluation of the test’s ability to accurately detect numerous chromosomal variations of different types, sizes, and genome locations when compared to several analytically validated test methods. The FDA found that the CytoScan Dx Assay could analyse a patient’s entire genome and adequately detect chromosome variations in regions of the genome associated with intellectual and developmental disabilities.

Additionally, the agency’s review included a study that compared the performance of the CytoScan Dx Assay to tests that are 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 device should not be used for stand-alone diagnostic purposes, pre-implantation or prenatal testing or screening, population screening, or for the detection of, or screening for acquired or genetic aberrations occurring after birth, such as cancer. The 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, according to a statement issued by the FDA.

Interpretation of test results is intended to be performed only by healthcare professionals who are board certified in clinical cytogenetics or molecular genetics, the statement said.

Affymetrix CytoScan Dx Assay is manufactured by Affymetrix, Inc, located in Santa Clara, California.

Source: India Medical Times