Diphallia

Diphallia, or penile duplication (PD), is a medicalcondition in which a male infant is born with two penises. It is estimated that one out of 5 million live births in the United Statesresults in a diphallic birth defect^{[citation needed]}.

When diphallia is present, it is usually accompanied by other congenitalanomalies such as renal, vertebral, hindgutor anorectalduplication. There is also a higher risk of spina bifida. Infants born with PD and its related conditions have a higher death rate from various infections associated with their more complex renal or colorectal systems.

It is thought diphallia occurs in the fetusbetween the 23rd and 25th days of gestationwhen an injury, chemical stress, or malfunctioning homeoboxgenes hamper proper function of the caudal cell massof the fetal mesodermas the urogenital sinusseparates from the genital tubercleand rectumto form the penis.

This rare condition has been documented in pigsand other mammals. It is commonly mistaken that all sharkshave this condition, but in reality they have a pair of "claspers" which serve a reproductive function.

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It uses material from the http://en.wikipedia.org/wiki/Diphallia Wikipedia article Diphallia.