Match each statement (a–e) with the best answer from the following list: consultand, 50%, prior probability, 66.7%, obligate carrier, 100%.

A person who on the basis of family history must be a heterozygous carrier of a recessive mutant allele

Key Concepts

Heterozygous Carrier

A heterozygous carrier is an individual who possesses two different alleles for a particular gene, one of which may be a recessive mutant allele. In the context of genetic disorders, this means the person does not express the disorder but can pass the recessive allele to offspring. Understanding this concept is crucial for interpreting family histories and predicting inheritance patterns.

Recessive Mutant Allele

A recessive mutant allele is a variant of a gene that does not manifest its effects unless two copies are present (homozygous condition). In a heterozygous individual, the dominant allele masks the expression of the recessive allele. This concept is essential for understanding how certain genetic traits are inherited and the implications for family members.

Obligate Carrier

An obligate carrier is an individual who must carry a specific allele based on their family history, typically because they have an affected relative. In the case of recessive disorders, if both parents are carriers, their offspring have a 25% chance of being affected, a 50% chance of being carriers, and a 25% chance of being unaffected. Recognizing obligate carriers helps in genetic counseling and risk assessment.