Description

A man in early adolescence, born out of consanguineous marriage, presented with progressive gait unsteadiness and recurrent sinopulmonary and soft tissue infections for 5 years. On examination, he had bulbar conjunctival telangiectasia (figure 1), oculomotor apraxia, bilateral cerebellar signs and bilateral, horizontal, coarse, gaze evoked nystagmus. MRI of the brain revealed diffuse cerebellar atrophy. Laboratory investigations revealed elevated serum alfa-fetoprotein with a decreased serum IgA level. The patient was diagnosed with ataxia telangiectasia (A-T), which was confirmed with whole genome sequencing.

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Figure 1

Ocular examination showing bulbar conjunctival telangiectasia.

A-T is an autosomal recessive, inherited, neurodegenerative disorder characterised by progressive cerebellar degeneration, associated with immunodeficiency and increased risk for malignancy.1 2 A-T was first described by Elena Boder and Robert P. Sedgwick in 1957 as a familial syndrome of cerebellar ataxia, frequent pulmonary infections and oculocutaneous telangiectasia. Patients with A-T have a significantly increased incidence of cancers (leukaemias, lymphoid malignancies and solid tumours, such as oesophageal, gastric, liver and breast carcinomas).1 Clinicians must be aware of the potential for malignancy, and particularly haematological malignancy, in these patients. Conjunctival telangiectasia can be seen in some inherited systemic syndromes such as A-T, hereditary haemorrhagic telangiectasia, Fabry’s disease, Bloom syndrome, Alport syndrome and may also be associated with chronic ocular surface disorders such as ocular rosacea.3 Telangiectasia in A-T is noted primarily on interpalpebral, bulbar conjunctiva over the exposed portion of sclera and they may appear much later than neurological symptoms.4 Adults with milder forms of the disease (variant A-T) often do not have ocular telangiectasia.5 Therefore, their absence does not exclude the diagnosis of A-T. They do not bleed usually and they are sometimes misdiagnosed as chronic conjunctivitis. Abnormal eye movements such as oculomotor apraxia, nystagmus, accommodation abnormalities and hypometric saccades may be associated with A-T. Mutation of the ATM gene responsible for coordinating the signalling pathways in response to genotoxicity leads to A-T.6 The importance of vigilant ophthalmic examination in the diagnosis of hereditary neurodegenerative disorders is hereby emphasised.