Occipital horn syndrome

Formerly considered an Ehlers–Danlos type IX syndrome, occipital horn syndrome (OHS), is a milder and rare form of Menkes disease where the patient reaches adulthood. As an X-linked disease, it typically occurs in male subjects, while female subjects are usually healthy carriers.

OHS is mainly characterized by connective tissue disorders and slightly subnormal intelligence or signs of autonomic dysfunction are the only apparent neurological abnormalities, in connection with molecular defects in copper metabolism.

The main clinical features, including cutis laxa, bony exostoses, and bladder diverticula are attributed to a decreased activity of lysyl oxidase (LOX), a cupro-enzyme involved in collagen crosslinking.

Occipital horn syndrome patients have low-normal levels of serum copper and ceruloplasmin and abnormal plasma and CSF catecholamines.

Patients may show mild to moderate intellectual disability. 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.
Occipital horn syndrome