A boy with Klinefelter syndrome (47,XXY) is born to a mother who is phenotypically normal and a father who has the X-linked skin condition called anhidrotic ectodermal dysplasia. The mother's skin is completely normal with no signs of the skin abnormality. In contrast, her son has patches of normal skin and patches of abnormal skin. Using the appropriate genetic terminology, explain the son's skin phenotype.

Key Concepts

Klinefelter Syndrome

Klinefelter syndrome is a genetic condition in males characterized by the presence of an extra X chromosome, resulting in a 47,XXY karyotype. This condition can lead to various physical and developmental features, including infertility, reduced testosterone levels, and sometimes, skin abnormalities. Understanding this syndrome is crucial for explaining the genetic background of the boy's phenotype.

X-linked Inheritance

X-linked inheritance refers to the pattern of inheritance for genes located on the X chromosome. Conditions like anhidrotic ectodermal dysplasia are passed from carrier mothers to affected sons, as males have only one X chromosome. This concept is essential for understanding how the father's X-linked condition may influence the son's skin phenotype, despite the mother being phenotypically normal.

Phenotype and Genotype

Phenotype refers to the observable characteristics or traits of an organism, while genotype is the genetic makeup that determines these traits. In this case, the son's skin phenotype, which includes patches of normal and abnormal skin, results from the interaction of his Klinefelter syndrome genotype and the X-linked condition inherited from his father. This distinction is vital for accurately describing the son's skin condition.