Table 1.

Genetic diseases and abnormalities that result in azoospermia at the post-testicular (obstructive azoospermia), pre-testicular and testicular (non-obstructive azoospermia) levels.

Obstructive Azoospermia of Genetic Origin
Cystic Fibrosis
Congenital Bilateral Absence of the Vas Deferens
Congenital Unilateral Absence of the Vas Deferens (CUAVD)
Congenital Bilateral Epididymal Obstruction and Normal Vasa
Young Syndrome

Nonobstructive Azoospermia of Genetic Origin
Genetic Pre-testicular Causes of NOA
Hypothalamic HH
Congenital HH
Adult-onset genetic hypothalamic HH
Pituitary Disorders Associated with Hypogonadism
Generalized anterior pituitary hormone deficiency
Selective gonadotropin deficiency
Genetic Testicular Disorders
Affecting Spermatogenesis and Androgen Production
Klinefelter syndrome
XX male syndrome
Mutation in X-linked USP 26
X-linked SOX3 mutation
Bilateral anorchia
Noonan syndrome
45 X/46XY mosaicism (mixed gonadal dysgenesis)
Affecting Spermatogenesis
Y chromosome microdeletion
Autosome translocations
Monogenic disorders
Multifactorial disorders (e.g., cryptorchidism)
Affecting Androgen Production or Action
Androgen receptor mutation
Steroidogenic acute regulatory protein StAR mutation
3BHSD type 2 deficiency
SRD5A2 mutation
Dysfunctional Cell Regulatory Pathways
Epigenetic Defects
Genetic Abnormities at the Primordial Germ Cell Level