What is the definition of Occipital Horn Syndrome?

Occipital horn syndrome (OHS) is a genetic condition that affects the connective tissue, skeleton, and nervous system. Symptoms of OHS usually begin in early childhood. They may include wedge-shaped calcium deposits at the base of the skull (occipital horns), loose skin and joints, and dysfunction of the nerves that regulate nonvoluntary body functions (dysautonomia). Other symptoms may include bladder diverticula, coarse hair, low muscle tone, and mild intellectual disability. This condition is a milder form of Menkes disease, which affects copper levels in the body. OHS is caused by genetic changes (DNA variants) in the ATP7A gene, and it is inherited in an x-linked recessive pattern. It can be diagnosed based on the symptoms, genetic testing, and other blood tests. Treatment for OHS is based on managing the symptoms.  

What are the alternative names for Occipital Horn Syndrome?

  • OHS
  • Cutis laxa X-linked
  • Ehlers-Danlos syndrome, occipital horn type (formerly)
  • EDS IX (formerly)

What are the causes for Occipital Horn Syndrome?

Occipital horn syndrome (OHS) is caused by genetic changes (DNA variants) in the ATP7A gene. Variants in this gene can also cause a more severe form of OHS called Menkes syndrome.

What are the symptoms for Occipital Horn Syndrome?

The following list includes the most common signs and symptoms in people with occipital horn syndrome. These features may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list does not include every symptom or feature that has been described in this condition.

Signs and symptoms may include:
  • Wedge shaped calcifications at the base of the skull (occipital horns)
  • Loose skin and joints
  • Bladder pouches (diverticula)
  • Blood vessel abnormalities
  • Dysautonomia (chronic diarrhea, orthostatic hypotension)
  • Mild cognitive deficits
  • Decreased muscle tone (hypotonia)
  • Hair abnormalities
The symptoms of occipital horn syndrome usually appear by early childhood. Most people with OHS have normal intelligence or only mild intellectual delay. Because this condition is so rare, there is not much information about how this condition affects people as they get older. There is some evidence that serious gastrointestinal, breathing, or bleeding complications can develop by early adulthood. 

What are the current treatments for Occipital Horn Syndrome?

There is no specific treatment for occipital horn syndrome. Treatment is based on managing the symptoms.

Specialists who may be involved in the care of someone with occipital horn syndrome include: 
  • Medical geneticist
  • Urologist
  • Neurologist
  • Nutritionist

Is Occipital Horn Syndrome an inherited disorder?

Occipital horn syndrome is inherited in an X-linked recessive pattern. X-linked means that the gene for the condition is located on the X-chromosome, one of the sex chromosomes. In males (who have only one X chromosome), one changed copy of the gene is enough to cause the condition. In females (who have two X chromosomes), a change needs to occur in both copies of the gene to cause the condition.

X-linked recessive conditions affect males much more frequently than females. Females, who have one changed gene, are called carriers. While, most female carriers have no signs or symptoms of the condition, in rare cases, female carriers may experience some mild signs or symptoms.

A female who carries one X-linked gene change has a 50% or 1 in 2 chance of having a son with the condition and a 50% chance of having a daughter who is also a carrier. A male with an X-linked recessive condition cannot pass on the disorder to his sons, but all of his daughters will be carriers.

Sometimes a male child is the first person in a family with the condition. In this case, the gene change may have been inherited from the mother, or the change may have occurred by chance for the first time in the child (de novo).