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When a person is reported to have two variants in a gene, there are two possibilities:
- The two variants are on the same chromosome, or
- The two variants are each on different chromosomes.
Two variants on different chromosomes
More commonly, a person has one GJB2 variant on each chromosome, (called trans, meaning across). Remember, chromosomes come in pairs. In this case, the GJB2 gene on each chromosome carries a variant.
Two variants on the same chromosome
Less commonly, a person has two GJB2 variants on the same chromosome (called cis, meaning same side). In this case, one chromosome has two GJB2 variants but the other has no variants. This person is considered a carrier for GJB2-related hearing loss. Learn more about carrier screening