An 18-month-old girl with macrosomia exhibits a genetic abnormality at KCNQ10T1. What genetic mechanism is likely responsible for her condition?

• A. Anticipation
• B. Pleiotropy
• C. Non-paternity
• D. Imprinting

Answer: (D)

The condition described in the question likely involves genetic imprinting related to the KCNQ10T1 region, which is known to be involved in genetic disorders. Imprinting refers to a phenomenon where certain genes are expressed in a parent-of-origin-specific manner, meaning that only one allele of a gene is active while the other is silenced, depending on whether it was inherited from the mother or the father.

In the case of disorders associated with the KCNQ10T1 region, such as those affecting growth or development, imprinting can lead to various phenotypes depending on which parent's allele is active. The presence of macrosomia, or excessive growth, indicates that there may be an overactivity of growth-related genes in this region, likely due to the expression pattern dictated by imprinting.

Anticipation refers to a phenomenon in genetic conditions where symptoms become more severe or appear at an earlier age in successive generations, which does not directly relate to the genetic abnormality in this question. Pleiotropy describes a situation where one gene influences multiple phenotypic traits; although it might describe some genetic conditions, it does not specifically relate to the mechanism at KCNQ10T1. Non-paternity refers to situations where the father of a