Trisomy 18p is an extremely rare chromosomal anomaly with a poorly defined clinical phenotype. Reported manifestations include short stature, mild, moderate or severe developmental delay and intellectual disability, variable but mild facial dysmorphism, and epilepsy.

Absence of any measurable level of sperm in his semen, resulting from a defect in the production of spermatozoa in the testes. Can be differentiated from obstructive azoospermia on the basis of testicular biopsy.