Scientists at the Baylor DNA Diagnostic Laboratory developed the test after a team of Baylor researchers announced in September their discovery of the defective gene that causes Rett syndrome, a neurodevelopmental disorder that affects girls.

"Using a blood sample from someone suspected of having Rett syndrome, we can analyze the MECP2 gene on the X chromosome for the mutation that causes the disorder," said Dr.Benjamin Roa, acting director of the Baylor DNA Diagnostic Laboratory.

The presence of the mutation can confirm diagnosis of Rett syndrome. Blood samples from other family members can be
screened for the mutation, but it is rare that the disorder is inherited because the mutation occurs at random.

The test requires an analysis of the entire MECP2 gene, a lengthy process that can take up to a month before results are available, Roa said. Physicians and genetic counselors can
request the Rett test for by calling

(800) 226-3624. Insurance companies may vary on whether they will cover the cost of $950. If a
mutation is identified in the affected individual, other family members may be studied at a lower cost of $250. As with all other tests for genetic diseases, genetic counseling is strongly
recommended, Roa said.

The Rett test is one of more than 30 genetic testsavailable from the Baylor DNA Diagnostic Laboratory.

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