If only one twin has a certain disease, the twin pair is said to be

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If only one twin has a certain disease, it means that the twins have different phenotypes for that particular trait, making them discordant. Fraternal refers to twins that come from two different eggs and therefore have different genetics. Penetrant is a term used to describe the degree to which a gene or mutation causes a particular phenotype or trait. Karyotypic refers to the number and appearance of chromosomes in the cell. None of these terms accurately describe the situation of only one twin having a disease.

If Only One Twin Has a Certain Disease, the Twin