<unk>  is a very rare birth defect in humans, occurring about once in 5-10 million births, where a male child is born without a penis.  There were recently thought to be fewer but the condition is remarkably more frequent in India and South-east Asia. It is also known as aphallia [from the Greek, "a" for negative or no, and "phallia" for penis]. Most patients have no known family history of aphallia, and often have a normal male anatomy, save for the absence of the penis.
A partner condition is testicular or gonadal<unk> .  This is where the male child is born without gonads and consequently develops no testes.  The function of Leydig cells in the embryo is to convert the gonads into testicles in males-to-be and into ovaries in females.  In this condition, the process fails.<unk>  can exist independently after full testicular development, though the causes of this in particular are uncertain.  Testes are the sole producer of 5-alpha dihydrotestosterone (5aDHT) in the male body.  One cause of the gonads failing to metamorphose into testes is the absence of  5aDHT.  Therefore the masculizing process to allow for the development of the genital tubercle which eventually becomes the penis is halted.  In this scenario, the child is born with<unk>  and testicular<unk> .  Another slang term for this condition is "nullo".
The sufferers of just one of the conditions usually continue as males throughout their lives.  With very few exceptions the<unk>  and testicular agenetic is brought up as a female and eventually undergoes http://www.wikidoc.org/index.php/Sex_reassignment_surgery.  This is despite being 46xy karyotype male and having no female sexual characteristics. This is an unclear part of anatomy.  The organs that prevent the development of the embryo into a female are called Anti-Mullerian hormones.  They are commonly believed to be created in the testes, but male embryos without testes still appear to produce these hormones.
Penile agenesis
Epispadias
Dilated rete testis
Cryptorchidism
Loxoscelism
Renal ectopia
Penis enlargement
Micrognathism