Familial amyloidosis, Finnish type, or gelsolin amyloidosis, is a condition characterized by abnormal deposits of amyloid protein that mainly affect the eyes, nerves and skin. The 3 main features are amyloid deposits in the cornea (corneal lattice dystrophy), bilateral facial paralysis, and cutis laxa ("sagging" skin). Symptoms generally worsen with age. This condition is inherited in an autosomal dominant manner and is caused by mutations in the GSN gene. Treatment generally focuses on specific signs and symptoms. Plastic surgery may relieve problems caused by facial paralysis and cutis laxa.

Eye symptoms typically begin first. The amyloid deposits cloud the cornea, often leading to vision impairment. Other eye symptoms may include dryness, irritation and light sensitivity. Affected individuals may eventually develop cataracts and glaucoma.

As the condition progresses, the nerves become involved (typically in an individual's 40s). Dysfunction of the nerves in the head and face (cranial nerves) causes paralysis of facial muscles and decreased sensation, which can lead to difficulty speaking, chewing, and swallowing. Facial paralysis can also cause additional eye symptoms including ectropium (turning out of the eyelid), corneal ulcers, or droopy eyelids (ptosis). Affected individuals may also have peripheral neuropathy.Central nervous system symptoms such as impaired cognitive function are rare but have been reported in older individuals.

Skin manifestations may also begin in a person's 40s and include a thickened, sagging appearance and cutis laxa (loose skin that lacks elasticity), especially on the face. Cutis laxa worsens with age.

Other signs and symptoms that have been reported in some people include gastric motility changes, orodental problems, heart palpitations, cardiac conduction problems, and mild proteinuria.

In the later stages of the condition, individuals may have amyloid deposition in small blood vessels and vital organs, such as the kidney and heart; this can become life threatening. The mortality rate in affected individuals is thought to be slightly higher than in unaffected individuals; however, because the condition is so rare, conclusive studies regarding these statistics have not been performed. The primary causes of death in affected individuals are typically nephrotic syndrome; pneumonia from aspiration due to dysfunction of the bulbar muscles (those of the mouth and throat); or cerebral hemorrhage, likely from cerebral angiopathy (amyloid in the arteries of the brain).