What are the other Names for this Condition? (Also known as/Synonyms)

• IH (Isolated Hemihyperplasia)
• Isolated Hemihyperplasia (IH)
• Isolated Hemihypertrophy

What is Hemi 3 Syndrome? (Definition/Background Information)

• Hemi 3 Syndrome, or Isolated Hemihyperplasia, is a rare overgrowth syndrome characterized by an asymmetric regional body overgrowth, involving at least one limb
• It is also associated with an increased risk of developing embryonal tumors, principally nephroblastoma and hepoblastoma

(Source: Isolated hemihyperplasia; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Who gets Hemi 3 Syndrome? (Age and Sex Distribution)

• Hemi 3 Syndrome is a rare congenital disorder. The presentation of symptoms may occur at birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Hemi 3 Syndrome? (Predisposing Factors)

• A positive family history of neural tube closure defects may be an important risk factor for Hemi 3 Syndrome 
• Currently, no other risk factors have been clearly identified for the syndrome

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hemi 3 Syndrome? (Etiology)

A defect in the dorsal lip of the neural tube during embryonic development is theorized to cause Hemi 3 Syndrome (this condition is considered a neural tube closure defect).

What are the Signs and Symptoms of Hemi 3 Syndrome?

The signs and symptoms of Hemi 3 Syndrome may include:

• Embryonal neoplasm
• Skeletal muscle hypertrophy

Very frequently present symptoms in 80-99% of the cases:

• Asymmetry of the thorax
• Hemihypertrophy
• Scoliosis

Frequently present symptoms in 30-79% of the cases:

• Abnormality of the dentition
• Facial asymmetry
• Mild intellectual disability

Occasionally present symptoms in 5-29% of the cases:

• Abnormality of cardiovascular system morphology
• Cryptorchidism
• Impaired pain sensation
• Inguinal hernia
• Myelomeningocele
• Nephroblastoma

(Source: Hemi 3 Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Hemi 3 Syndrome Diagnosed?

Hemi 3 Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hemi 3 Syndrome?

The complications of Hemi 3 Syndrome may include:

• Severe back pain due to scoliosis
• Crowding of organs in the chest cavity
• Compromised function of the lungs and heart
• Low self-esteem, depression and anxiety
• Associated complications from the formation of cancer in the kidney or liver

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Hemi 3 Syndrome Treated?

Presently, there is no cure for Hemi 3 Syndrome. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Hemi 3 Syndrome be Prevented?

Currently, Hemi 3 Syndrome may not be preventable.

• If there is a family history of neural tube defects, then genetic counseling may help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of disorders such as Hemi 3 Syndrome

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Hemi 3 Syndrome? (Outcomes/Resolutions)

• The prognosis of Hemi 3 Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Hemi 3 Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/