The gene for Tay-Sachs disease codes for a nonfunctional form of the enzyme hexosaminidase A (or Hex A). It has been found that a person with only one-third the maximum amount of Hex A can function absolutely normally. Please characterize the heredity of Tay-Sachs disease.

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Tay-Sachs disease is a recessive genetic disorder, which means a person needs to inherit two copies of the nonfunctional gene, one from each parent, in order to have the disease. A person with only one-third the maximum amount of Hex A can function normally, which suggests that having one functional copy of the gene is enough to prevent the disease from developing. This is consistent with the inheritance pattern of a recessive disorder, where a carrier (heterozygous individual) has one functional and one nonfunctional copy of the gene, and is able to produce enough of the functional product to avoid the disease phenotype.

The Gene for Tay-Sachs Disease Codes for a Nonfunctional Form