A 29 year-old Ashkenazi Jewish woman completed pre-pregnancy carrier screening and was found to be a carrier for Tay-Sachs and Spinal Muscular Atrophy (SMA). In order to determine if her husband was a carrier for Tay-Sachs, his doctor ordered testing to check his hexosaminidase A levels, the enzyme that is low or absent in Tay-Sachs patients. The husband’s enzyme levels were abnormal, suggesting he was a carrier of Tay-Sachs. However, when he went to get Tay-Sachs genetic testing, it came back negative/normal. It was not until they had their first child that the couple realized the husband’s genetic testing was not a full sequencing of the HEXA gene, but rather, only tested for the most common variants in Tay-Sachs.
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