Which of the following conditions is commonly associated with cryptorchidism?

The association of cryptorchidism with certain conditions is well-documented, with Down syndrome being notably impacted. Cryptorchidism, which refers to the absence of one or both testes from the scrotum, is seen more frequently in individuals with Down syndrome than in the general population. This is partly due to the genetic and developmental anomalies associated with the extra chromosome, which can affect the positioning and descent of the testes during fetal development.

In regards to the other options, X-linked ichthyosis is primarily a skin condition related to a deficiency in an enzyme that affects keratinization and does not have a significant correlation with cryptorchidism. Turner syndrome, characterized by the absence of all or part of a second sex chromosome in females, can involve various reproductive system abnormalities, but it is not directly linked to cryptorchidism. Congenital adrenal hyperplasia leads to disorders of sexual differentiation, but it is more related to adrenal hormone production issues than the descent of the testes. Thus, Down syndrome is the condition most commonly associated with cryptorchidism.