Absence of any measurable level of sperm,whereby spermatozoa cannot be observed even after centrifugation of the semen pellet.

Inability to conceive for at least one year after trying and having unprotected sex. Causes of female infertility include endometriosis, fallopian tubes obstruction, and polycystic ovary syndrome. Causes of male infertility include abnormal sperm production or function, blockage of the epididymis, blockage of the ejaculatory ducts, hypospadias, exposure to pesticides, and health related issues.

Wasting (atrophy) of the testicle (the male gonad) manifested by a decrease in size and potentially by a loss of fertility.

Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).

Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering.

Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.