Alström Syndrome

Clinical Characteristics

Ocular Features:

Progressive failure of rods and cones begins in the first year of life and inevitably leads to blindness. Central vision is lost first and nystagmus in early childhood results. Photophobia can be evident in the first year of life. Early ERGs show severe impairment of cone responses with little or no rod dysfunction. In the second and third decades all rod and cone responses are extinguished. Vision can be less than 20/400 by the age of 10 years and usually all light perception is lost by the beginning of the third decade. Pale optic nerves with retinal arteriorlar narrowing and posterior subcapsular cataracts have been seen.

Systemic Features:

This is a multisystem disease with onset in the first year of life. Infants may have a normal birth weight but develop truncal obesity in the first year. Hearing loss is evident in the first decade. Insulin resistant type 2 diabetes mellitus with hyperinsulinemia often occurs in childhood and may be accompanied by hypothyroidism and hypogonadotropic hypogonadism. Acanthosis nigricans and some degree of pulmonary dysfunction are common. The majority of individuals (70%) develop restrictive or dilated cardiomyopathy, many in the first months of life, resulting in cardiac failure. The liver may become cirrhotic and renal failure occurs late. Intelligence is usually normal but many patients (25-30%) have early delays in their developmental milestones perhaps secondary to growth hormone deficiency which has been reported (98% are short in stature). Lifespan is short and many die in childhood. Few live beyond the age of 40 years.

Alstrom syndrome has some similarities to Bardet-Biedl syndrome (209900) but differs in the absence of mental deficiency and polydactyly.

Genetics

This is an autosomal recessive disorder resulting from homozygous mutations in the ALMS1 gene on chromosome 2 (2p13). The ALMS1 protein product is found in many cells throughout the body and is located in centrosomes and the base of cilia. Its function is unknown.

More than 320 mutations have been reported. However, many cases remain in which no mutation has been found suggesting additional genetic heterogeneity remains.

Treatment

Treatment Options:

No treatment is available for the basic disease.

References

Article Title:

Spectral-domain optical coherence tomography findings in Alström syndrome

Dotan G, Khetan V, Marshall JD, Affel E, Armiger-George D, Naggert JK, Collin GB, Levin AV. Spectral-domain optical coherence tomography findings in Alstrom syndrome. Ophthalmic Genet. 2017 Jan 23:1-6.

PubMed ID:

28112973