Abstract: Sex linkage is the phenotypic expression of an allele that is related to the chromosomal
sex of the individual. In humans, there are many more X-linked traits since there are many more genes on the
X than on the Y. This paper highlights the genetic traits of three kinds of sex-linked inherited disease, X-
linked dominant inherited disease, X-linked recessive inherited disease and Y-linked inherited disease, from a
genetic perspective in order to improve awareness of the sex-linked inherited diseases. The prevalence of some
genetic diseases would be reduced, and the population-based hereditary predisposition as well as quality would
be improved by evaluation of recurrence risk of a genetic disease and genetic counseling.

Key words: Linkage（genetics）, X cheromosome, Y chromosome, Prenatal diagnosis