Table 1.

Pathophysiology of congenital cryptorchidism.

Primary hypogonadism	Whole testicular dysfunction	Testicular dysgenesis in 46,XY DSD Testicular dysgenesis in sex chromosome DSD with a Y chromosome (45,X/46,XY, 46,XX/47,XXY, etc.) 46,XX ovotesticular DSD 46,XX testicular DSD 46,XY testicular regression syndrome Klinefelter syndrome Noonan syndrome Trisomy 21 Prader-Willi syndrome Other rarer syndromes
	Leydig cell-specific dysfunction	Leydig cell hypoplasia/aplasia Steroidogenic defects INSL3 defects
Central hypogonadism	Whole testicular dysfunction	Combined pituitary hormone deficiency Isolated gonadotropin deficiency with hyposmia/anosmia (Kallmann syndrome) Isolated gonadotropin deficiency without hyposmia/anosmia
	Leydig cell-specific dysfunction	LHβ-subunit deficiency
Target organ defects	DHT deficiency	5α-reductase type 2 deficiency
	Androgen insensitivity syndrome	Androgen receptor defects
Anatomic defects	Abdominal wall defects	Prune belly syndrome Cloacal malformations
Ill-known mechanisms	PMDS	AMH mutations AMHR2 mutations
	Idiopathic isolated cryptorchidism

DHT, dihydrotestosterone; DSD, disorder of sex development; PMDS, persistent Müllerian duct syndrome.