Alström's Syndrome
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Alström's syndrome is a very rare autosomal recessive disorder characterised by progressive cone-rod dystrophy leading to blindness, sensorineural hearing loss, childhood obesity associated with hyperinsulinaemia, and type 2 diabetes mellitus.[1] The diagnosis should be considered in all patients with infantile cone and rod retinal dystrophy, especially if the weight is above the 90th centile or if there is infantile cardiomyopathy.
- Dilated cardiomyopathy occurs in approximately 70% of patients during infancy or adolescence.[2]
- Renal failure, pulmonary, hepatic, and urological dysfunction are often observed, and systemic fibrosis develops with age.[2]
- The gene map locus for the affected mutated gene (ALMS1) is 2p12-13.[3]
Epidemiology
- Alström's syndrome is rare; only about 425 people worldwide are known to be affected.[4]
Presentation
Alström's syndrome in childhood is difficult to recognise without the development of infantile cardiomyopathy and may not be identified until diabetes mellitus develops in the second or third decade.
- Severe progressive infantile retinal dystrophy (visual acuity of 6/60 or less by 10 years of age and no light perception by age 20), with or without nystagmus.
- Deafness.
- Obesity.
- Acanthosis nigricans.
- Cardiomyopathy.
- Nephropathy.
- Alström's syndrome may also be associated with:[5]
- Hypothyroidism.
- Liver dysfunction.
- Metabolic abnormalities, including hyperuricaemia and elevated serum triglyceride and pre-beta-lipoprotein.[2]
- Small penis.
- Gastrointestinal reflux.
Differential diagnosis[2]
- Bardet-Biedl syndrome is similar (with retinitis pigmentosa, deafness, obesity and diabetes mellitus) but also includes mental defect, polydactyly or hypogonadism.
- The retinal lesion of Alström's syndrome causes nystagmus and early loss of central vision in contrast to the initial loss of peripheral vision found in other pigmentary retinopathies.
Investigations
- Blood tests for fasting blood glucose, liver function tests, renal function tests, thyroid function tests and triglyceride levels.
- A thorough assessment of vision and ophthalmoscopy by an ophthalmologist.
- Hearing assessment by an ear, nose and throat specialist.
- Assessment of heart function, including echocardiogram.
Management
There is no specific treatment but management will be required for:
- Diabetes.
- Renal impairment.
- Liver dysfunction.
- Visual impairment.
- Deafness.
- Heart failure and other features of cardiomyopathy, eg cardiac arrhythmias.
- Hypothyroidism.
Prognosis
- The prognosis will depend on the progression of glucose intolerance, cardiomyopathy, renal dysfunction and liver impairment.
- Total blindness and deafness are likely to develop.
Further reading and references
Alstrom CH, Hallgren B, Nilsson LB Asander H; Retinal degeneration combined with obesity, diabetes mellitus and neurogenous deafness: a specific syndrome (not hitherto described) distinct from the Laurence-Moon-Biedl syndrome. A clinical endocrinological and genetic examination based on a large pedigree. Acta Psychiat. Neurol. Scand. 1959, 34 (suppl. 129):1-35.
Alström Syndrome; Alström Syndrome, Online Mendelian Inheritance in Man (OMIM)
Zumsteg U, Muller PY, Miserez AR; Alstrom syndrome: confirmation of linkage to chromosome 2p12-13 and phenotypic heterogeneity in three affected sibs. J Med Genet. 2000 Jul37(7):E8.
Alström syndrome; Alström syndrome, U.S. National Library of Medicine
Alström syndrome; Alström syndrome, Medline Plus Medical Encyclopedia