A “pseudodeficiency allele” reduces enzyme activity but does not cause a disease. A pseudodeficiency allele does not cause Tay-Sachs disease in a carrier or in the children who inherit the pseudodeficiency allele. Even if a person has one Tay-Sachs mutation and one pseudodeficiency allele, they will not develop Tay-Sachs disease. Approximately 30% of non-Ashkenazi Jewish and 3% of Ashkenazi Jewish individuals who are identified as carriers by enzyme analysis have a benign pseudodeficiency allele.