Alstrom syndrome is caused by pathogenic variants in the ALMS1 gene and is inherited in an autosomal recessive manner. To be affected, an individual must inherit two disease-causing copies of ALMS1, one from each parent. According to GeneReviews, the parents of an affected child are obligate carriers of one pathogenic ALMS1 variant; carriers are asymptomatic and not at risk of developing the disorder. At each pregnancy, carrier parents have a 25% chance of having an affected child, a 50% chance of having an asymptomatic carrier, and a 25% chance of having an unaffected, non-carrier child.

GeneReviews notes that genotype-phenotype correlations in Alstrom syndrome are challenging to establish because almost all identified pathogenic variants are null variants and the majority of affected individuals are compound heterozygous, carrying two different rare variants reported in only a few families.

GeneReviews identifies clinical findings that, when present, prompt evaluation for Alstrom syndrome, with features evolving across developmental periods. Cone-rod dystrophy with secondary nystagmus and photodysphoria typically appears within the first year of life; full-field electroretinography, which GeneReviews identifies as required to confirm cone-rod dystrophy, is abnormal from birth in affected individuals. Additional findings include early childhood-onset truncal obesity; progressive bilateral sensorineural hearing impairment, usually identified between ages one and ten years; infantile or adolescent- to adult-onset cardiomyopathy; and insulin resistance or type 2 diabetes mellitus, which may develop in childhood or adolescence.

GeneReviews distinguishes Alstrom syndrome from Bardet-Biedl syndrome, noting that polydactyly, cognitive impairment, and structural heart or genitourinary defects are not typical features of Alstrom syndrome and, when present, indicate evaluation for alternative diagnoses.

No FDA-approved treatments are listed for Alstrom syndrome in this packet. According to GeneReviews, no therapy currently exists to prevent the progressive multi-organ involvement characteristic of the syndrome. Management focuses on coordinated multidisciplinary care to address each affected system as manifestations develop.

GeneReviews outlines management approaches for individual features, which include ophthalmologic support and early educational planning in anticipation of progressive vision loss; audiologic assessment and hearing amplification strategies, with GeneReviews noting that digital hearing aids and, in some individuals, cochlear implantation have been used; dietary and physical activity approaches to address obesity; and standard pharmacological therapies for cardiomyopathy and diabetes management.

GeneReviews notes that substances with contraindications in the setting of renal, hepatic, or myocardial disease require careful consideration given Alstrom syndrome's multi-organ profile, and that therapeutic interventions targeting one organ system may have implications for other affected systems.

Setmelanotide carries an FDA orphan drug designation specifically for Alstrom syndrome and is currently under investigation as a potential therapy. A specialist team with experience in multisystem rare disease management guides individualized care planning.

Formal prognostic data for Alstrom syndrome are not specified in this packet, but GeneReviews describes a progressive clinical course across multiple organ systems. Vision loss progresses to blindness in most individuals; hearing impairment is typically progressive over time. Cardiomyopathy, progressive renal dysfunction, and hepatic disease each contribute to the long-term clinical course. GeneReviews notes wide clinical variability among individuals, including among siblings. The pace of multi-organ progression and the specific organ systems most affected differ from person to person. Annual surveillance across multiple organ systems is described in GeneReviews as an important component of ongoing clinical management.

Alstrom syndrome is the subject of ongoing clinical research. A small number of clinical trials are currently active, including natural history registries, studies examining novel therapies in related ciliopathies, and observational research addressing long-term outcomes. The published literature includes 68 classified publications, with case reports and case series representing the dominant research output, reflecting the rarity of this condition. GeneReviews notes that ClinicalTrials.gov and the EU Clinical Trials Register serve as resources for identifying active studies. Alstrom Syndrome International and Alstrom Syndrome UK may serve as additional resources for individuals seeking information about research participation and disease-specific support.