Overview
Diphallia, also known as penile duplication or double penis, is a very rare birth condition where a male baby is born with two penises instead of one. This happens when something goes wrong during the early weeks of pregnancy, around the 23rd to 25th day, when the genitals are forming. The exact cause is not fully understood, but it is thought to involve a mix of genetic and environmental factors during fetal development. The two penises can vary a lot from person to person. They may be side by side or one on top of the other. They can be equal in size or one may be much smaller than the other. Each penis may or may not have a urethra (the tube used to pass urine). Because of this, many people with diphallia also have other differences in their urinary or digestive systems, such as problems with the bladder, kidneys, or rectum. Treatment usually involves surgery, often done in infancy or early childhood. The goal is to remove the extra penis, correct any urinary problems, and help the child have normal function. With the right surgical care, many people with diphallia can live healthy lives, though some may need multiple operations over time.
Key symptoms:
Two penises present at birthPenises may be side by side or stacked on top of each otherOne or both penises may have a urethra (urine tube)Difficulty urinating or abnormal urine streamUrethra opening in the wrong place (hypospadias or epispadias)Bladder abnormalitiesKidney problemsAbnormalities of the rectum or anusSpinal abnormalities in some casesDuplicated scrotum or other genital differences in some cases
Clinical phenotype terms (29)— hover any for plain English
Sporadic
Usually appears on its own, not inherited from a parent
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Diphallia.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Diphallia at this time.
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Specialists
View all specialists →No specialists are currently listed for Diphallia.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Diphallia.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which penis or urinary opening is functional, and what does that mean for surgery?,Are there any other organs affected, such as the kidneys, bladder, or bowel?,How many surgeries might my child need, and when should they happen?,What are the expected outcomes for urinary function and sexual function in adulthood?,Should we do genetic testing, and could this affect future pregnancies?,What kind of psychological support do you recommend for my child as they grow up?,Are there any specialists or centers with more experience treating diphallia that we should see?
Common questions about Diphallia
What is Diphallia?
Diphallia, also known as penile duplication or double penis, is a very rare birth condition where a male baby is born with two penises instead of one. This happens when something goes wrong during the early weeks of pregnancy, around the 23rd to 25th day, when the genitals are forming. The exact cause is not fully understood, but it is thought to involve a mix of genetic and environmental factors during fetal development. The two penises can vary a lot from person to person. They may be side by side or one on top of the other. They can be equal in size or one may be much smaller than the othe
How is Diphallia inherited?
Diphallia follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Diphallia typically begin?
Typical onset of Diphallia is neonatal. Age of onset can vary across affected individuals.