Hypomyelination with congenital cataracts (HCC)



Autosomal recessive

Inheritance from both parents will result in the disease

Age range at onset:

Around 1 year old

Specialists you may see:


Born with cataracts in both eyes, those with HCC typically otherwise develop normally in their first year. Development then slows, with weakness, spasticity, seizures and atrophy in their legs making walking increasingly difficult. Some also experience scoliosis and many have peripheral neuropathy. Mild to moderate intellectual disability and dysarthria are also typical.


HCC is caused by mutations in the FAM126A gene, which creates a protein called hyccin. These mutations prevent or reduce the production of hyccin; those producing no hyccin have more severe symptoms than those with a reduced level. Although the role of hyccin is not fully understood, it is active in the lens of the eye and presumed to be involved in the formation of myelin (white matter).

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