Article Text

Familial amyloidosis of the Finnish type
  1. A A MEARZA,
  2. M AJAO,
  3. D E ETCHELLS
  1. Royal Victoria Eye Hospital, Westbourne, Bournemouth
  1. Dr A A Mearza, Department of Ophthalmology, The Royal Free Hospital, Pond Street, London NW3 2QG

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Editor,—Familial amyloidosis of the Finnish type (FAF), also known as Meretoja syndrome, is a rare autosomal dominant disorder first described by Meretoja in 1969.1 It is thought to develop as a result of a single point mutation involving the gelsolin gene located on chromosome 9. The estimated total number of patients in Finland is 400. Approximately 15 cases have been described outside Finland.2 We present the first case to be recognised in the UK demonstrating the classic signs of corneal lattice dystrophy, cranial neuropathy, and skin changes with an autosomal dominant pedigree.

CASE REPORT

A 73 year old woman presented with gradual reduction in visual acuity in her left eye. She had suffered recurrent corneal erosions affecting her left eye and was diagnosed as having corneal lattice dystrophy 18 years previously. At the time of presentation she was under investigation by a neurologist for progressive weakness of her facial muscles. There was no medical or drug history of note. Family members affected with corneal lattice dystrophy included her daughter and three cousins.

Examination revealed bilateral blepharochalasis, thickened facial skin, and bilateral lower motor neuron facial nerve palsies (Fig 1). Her visual acuity was 6/9 in the right eye and 6/60 improving to 6/36 with a pinhole in the left eye. She had bilateral corneal lattice dystrophy and an area of epithelial loss and sloughing associated with a mild left sided anterior uveitis (Fig 2). Lens opacities were also noted.

Figure 1

Photograph showing bilateral blepharochalasis, thickened facial skin, and bilateral lower motor neuron facial nerve palsies.

Figure 2

Area of epithelial loss and sloughing associated with a mild left sided anterior uveitis.

She was managed with topical mydriatics, antibiotics, and intensive lubricants. Despite an initial improvement, the cornea failed to re-epithelialise and a combined left penetrating keratoplasty and extracapsular cataract extraction was performed 5 months later. One year postoperatively, her acuity was 6/18 in the right eye, 6/9 in the left eye, and relatively symptom free on intensive lubricants.

The possibility of FAF was considered. Histology of the left corneal button removed at keratoplasty confirmed the characteristic amyloid deposition of lattice dystrophy. Nerve conduction studies demonstrated bilateral facial nerve conduction deficits as well as a subclinical right carpal tunnel syndrome. Scintigraphy using 123iodine labelled serum amyloid P component confirmed the expected systemic nature of the condition with amyloid deposits noted in the patient’s spleen and kidneys. DNA testing of the patient and her daughter revealed the presence of a point mutation in the gelsolin gene located on chromosome 9 confirming the diagnosis of Meretoja syndrome.

COMMENT

The Finnish type of familial amyloidosis is a systemic disease inherited in an autosomal dominant manner characterised by progressive cranial neuropathy (particularly involving the facial nerve), corneal lattice dystrophy, distal sensorimotor neuropathy, and varying degrees of skin change. The onset of symptoms is typically in the third and fourth decades with slow progress so that the majority are still in good health in their seventh decade.2 3

The condition is common in Finland but rare elsewhere. This patient and her daughter are the first two cases to be reported in the UK. The patient has the classic features of the disease and demonstrates the point mutation on the gelsolin gene responsible for it. However, although the corneal histology demonstrated the presence of amyloid deposits, immunocytochemistry showed no labelling of the deposits with antibodies to pre-albumin, amyloid A, and amyloid P. This is in contrast with other cases reported where amyloid stained with antisera to serum amyloid P.4Whether this represents a subtype of the condition is uncertain.

Various treatments are available targeted at each step in the pathogenesis of all types of amyloidosis with variable success and much research, including genetic manipulation, is being done in this regard.5 6 However, at present the treatment of this disorder is mainly based on alleviating symptoms.

References

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