Accessibility Tools

What is Hemihypertrophy?

Hemihypertrophy also referred to as hemihyperplasia, is a rare disorder in which there is overgrowth of only one side of the body due to an excess production of cells, causing asymmetry. In a normal cell, once the cell reaches a certain size there is a mechanism that turns off growth. However, in cases of hemihypertrophy, the cells on one side are not able to stop growing. Hemihypertrophy is a congenital disorder.

Causes of Hemihypertrophy

The exact cause of hemihypertrophy is not known in most cases, however there is evidence that the disorder runs in families. Other causes include:

  • Genetics play a role, but the genes that cause hemihypertrophy can differ from person to person. 
  • A mutation on chromosome 11 is suspected to be associated with hemihypertrophy.

Symptoms of Hemihypertrophy

The most noticeable symptoms of hemihypertrophy are that one side of the body is larger than the other side. Many times, a leg or an arm are going to be longer or larger in circumference than the other. However, it isn't always obvious. Sometimes, hemihypertrophy is difficult to note unless your child is laying down flat on a bed or surface, this is often called the "bed test" In other instances, a difference in their posture or gait may be noticed. Children with hemihypertrophy are at an increased risk for tumours, specifically those that occur in the abdomen. 

Diagnosis of Hemihypertrophy

Hemihypertrophy is diagnosed by physical examination. Your doctor may order other diagnostic tests to rule out other conditions such as Beckwith-Wiedemann syndrome (BWS), Proteus syndrome, Russell-Silver syndrome, and Soto’s syndrome. Diagnostic imaging test to screen for tumours may also be ordered.

Since this disorder is rare and often overlooked, it is recommended that the diagnosis be made by a clinical geneticist who is familiar with this condition.

Treatment for Hemihypertrophy

There is no cure for hemihyperplasia. Most of the treatment focuses on screening for tumour growth and treating the tumours. For abnormal limb size, orthopaedic treatment and corrective shoes may be recommended.