Men with this condition may exhibit azoospermia (no sperm production), oligozoospermia (small number of sperm production), or they may produce abnormally shaped sperm (teratozoospermia). This case of infertility occurs during the development of gametes in the male. Where a normal healthy male will have both an X and a Y chromosome, affected males have genetic deletions in the Y chromosome. These deletions affect protein production that is vital for spermatogenesis. Studies have shown that this is an inherited trait; if a male is fathered by a man who also exhibited Y chromosome deletions then this trait will be passed down. These individuals are thereby "Y-linked". Daughters are not affected and cannot be carriers due to their lack of a Y chromosome. Other
Age group 12–49 (Paternal age effect)
Aneuploidy, an abnormal number of chromosomes
Centriole
Neoplasm, e.g. seminoma
Idiopathic failure
Cryptorchidism
Trauma
Hydrocele, particularly hydrocele testis
Hypopituitarism in adults, and hypopituitarism untreated in children (resulting in growth hormone deficiency and proportionate dwarfism.) Mumps
Malaria
Testicular cancer
Defects in USP26 in some cases
Acrosomal defects affecting egg penetration
Idiopathic oligospermia – unexplained sperm deficiencies account for 30% of male infertility. Pre-testicular causes
Pre-testicular factors refer to conditions that impede adequate support of the testes and include situations of poor hormonal support and poor general health including:

Varicocele
Varicocele is a condition of swollen testicle veins.It is present in 15% of normal men and in about 40% of infertile men. It is present in up to 35% of cases of primary infertility and 69–81% of secondary infertility. Hypogonadotropic hypogonadism due to various causes
Obesity increases the risk of hypogonadotropic hypogonadism.
Parastremmatic dwarfism is a rare bone disease that features severe dwarfism, thoracic kyphosis (a type of scoliosis that affects the upper back), a distortion and twisting of the limbs, contractures of the large joints, malformations of the vertebrae and pelvis, and incontinence. The disease was first reported in 1970 by Leonard Langer and associates; they used the term parastremmatic from the Greek parastremma, or distorted limbs, to describe it. On X-rays, the disease is distinguished by a "flocky" or lace-like appearance to the bones. The disease is congenital, which means it is apparent at birth. It is caused by a mutation in the TRPV4 gene, located on chromosome 12 in humans. The disease is inherited in an autosomal dominant manner. Presentation
Parastremmatic dwarfism is apparent at birth, with affected infants usually being described as "stiff", or as "twisted dwarfs" when the skeletal deformities and appearance of dwarfism further present themselves. Skeletal deformities usually develop in the sixth to twelfth month of an infants life. The deformities may be attributed to osteomalacia, a lack of bone mineralization.Parastremmatic Dwarfism is further characterised by short stature, bowing of extremeties and further neuroskeletal dysplasia. Genetics
Parastremmatic dwarfism is caused by a missense mutation (where one amino acid is replaced by another in a gene sequence) in the TRPV4 gene, located on the long arm of human chromosome 12, at 12q24.11.