Which type of testing is used to confirm Tay-Sachs disease?

The correct choice confirms Tay-Sachs disease through the measurement of the HEXA enzyme activity. Tay-Sachs disease is caused by a deficiency in the hexosaminidase A (HEXA) enzyme, which is essential for breaking down certain fatty substances in the brain and nerve cells. When this enzyme is deficient or absent, it leads to the accumulation of GM2 gangliosides, resulting in the neurological symptoms associated with Tay-Sachs.

Testing for HEXA enzyme activity provides a direct confirmation of the deficiency that causes the disease. In individuals who are carriers or affected by Tay-Sachs, the enzyme activity is significantly reduced or absent, making this test a reliable method for diagnosis.

In contrast, genetic sequencing could also detect mutations in the HEXA gene and is used in various contexts of genetic testing; however, enzyme testing is more commonly employed as the initial confirmatory test for Tay-Sachs because it assesses enzyme activity directly linked to the disease. Other tests such as a complete blood count and hemoglobin electrophoresis are unrelated to Tay-Sachs and are utilized for different conditions, making them ineffective for diagnosing this particular genetic disorder.