Why Alström Syndrome Is Often Misdiagnosed (And What to Ask)

Most families with a child later diagnosed with Alström Syndrome have first lived with another diagnosis — sometimes for years. The wrong label is rarely a careless mistake. Alström is genuinely difficult to spot early, especially when only one organ system is involved. Knowing the most common mislabels can help families recognize when to ask about Alström and push for genetic testing.

1. Leber Congenital Amaurosis (LCA) and other isolated retinal dystrophies

When a baby presents with severe photophobia, nystagmus, and an abnormal ERG, the first label is often LCA or "early-onset retinal dystrophy." That label is reasonable based on eye findings alone — but it misses the systemic features.¹ Many panels for retinal dystrophies do include ALMS1, and re-checking the panel report or asking for a wider ciliopathy panel can resolve this when systemic signs emerge.

When to ask about Alström: if your child with an LCA-like diagnosis develops infant heart failure, rapid weight gain in the first year, or hearing loss in early childhood.

2. Bardet-Biedl Syndrome (BBS)

Both Alström and BBS are ciliopathies that share retinal degeneration, obesity, and metabolic features. The classical distinguishing features of BBS — extra fingers or toes (polydactyly) and learning disability — are usually absent in Alström.² Some children with mild or atypical BBS findings end up with an Alström diagnosis after expanded genetic testing.

When to ask about Alström: if your child has a BBS clinical impression but no polydactyly, intelligence within typical range, severe insulin resistance, or infantile cardiomyopathy.

3. Isolated dilated cardiomyopathy

Babies with severe heart failure in the first months of life are often investigated and treated as having "primary" or "idiopathic" dilated cardiomyopathy.³ Many recover heart function over time. The eye signs may be mild and easily missed in the NICU. Without a specific genetic test, the cardiac diagnosis stands alone.

When to ask about Alström: if your child recovered from infant heart failure and now has eye findings, weight gain, or hearing concerns. Ask whether the genetic panel for cardiomyopathy included ALMS1.

4. Usher Syndrome

Like Alström, Usher Syndrome causes progressive deafblindness. The differences are that Usher does not include cardiomyopathy, obesity, diabetes, or other systemic features, and Usher hearing loss is usually congenital rather than appearing in the first decade.⁴ Children with overlapping features can be tentatively labeled Usher and later reclassified.

When to ask about Alström: if your child has an Usher diagnosis but also has cardiomyopathy, severe weight gain, type 2 diabetes, or kidney/liver involvement.

5. Generic "obesity, type 2 diabetes, and metabolic syndrome"

Adults are sometimes diagnosed with Alström for the first time in their 30s or 40s after years of being treated for childhood obesity, severe insulin resistance, and progressive vision loss attributed to retinitis pigmentosa or another condition. The pieces never get connected.⁵

When to ask about Alström: for any adult with a personal history of childhood-onset obesity plus retinitis pigmentosa or progressive vision loss plus severe insulin resistance plus cardiomyopathy or unexplained kidney problems. The combination is so unusual that ALMS1 testing is appropriate.

Single-system thinking

Specialists naturally focus on the system they treat. A pediatric ophthalmologist sees the eyes; a pediatric cardiologist sees the heart. Without a generalist or geneticist pulling the threads together, the multisystem picture stays hidden until a third or fourth feature shows up.

Unfamiliarity with the syndrome

Around 1,200 cases of Alström are recognized worldwide. Most pediatricians have never seen one. Most cardiologists have never seen one. Recognizing it on a first encounter is the exception, not the rule.

Non-specific early signs

Photophobia, nystagmus, weight gain, and even infant cardiomyopathy each have many possible causes. Without genetic testing they can each be explained as something else.

Test cost and access

Genetic panels covering hundreds of genes are increasingly affordable but still not universally accessible, especially in countries without state-funded genomic services. When testing is delayed, diagnosis is delayed.

If your child's clinical picture is even partly suggestive, the following script often helps:

> "My child has [list features]. I've read that this combination can be seen in Alström Syndrome. Can we order an ALMS1 panel or a ciliopathy panel that includes ALMS1? If we can't access that, can we be referred to clinical genetics?"

Three points to be ready for:

1. The pediatrician may not have heard of Alström. That's fine — your job is to ask for the genetics referral, not to make the diagnosis yourself. 2. The geneticist may want to start with a smaller, targeted panel. That's reasonable; ALMS1 is included on most retinal-dystrophy and pediatric-cardiomyopathy panels. 3. Insurance or local guidelines may require pre-authorization. Ask the genetics team to write a letter of medical necessity citing the consensus guidelines.⁶

A negative ALMS1 test in a child with strong clinical features deserves a second look:

• Was the test sequencing only, or did it also include deletion/duplication analysis? Some Alström families have larger deletions that sequencing alone can miss.
• Was the entire gene covered, or only the most commonly mutated exons (8, 10, and 16)?
• Is there room for a re-analysis if your child develops more features over time? Reanalysis often picks up newly described pathogenic variants.

If after thorough genetic workup ALMS1 is excluded, your geneticist will move on to whole-exome or whole-genome sequencing to look for other ciliopathies or rare conditions.

• Alström Syndrome Diagnosis Hub
• Alström vs Bardet-Biedl Syndrome
• Alström vs Usher Syndrome
• The Diagnostic Journey for Alström Syndrome
• Variants of Uncertain Significance in Alström Testing

April 30, 2026.