A decision tree to help parents and clinicians think through when to consider Alström Syndrome and what to do next. Two flows: one for parents trying to make sense of unexplained signs in their child, and one for clinicians doing differential diagnosis.
This is an information tool, not a diagnostic instrument. Final decisions belong with your medical team.
For parents — text-based flowchart
START HERE: Has your child been diagnosed with Alström Syndrome?
┌─────────────────────────────┐
│ Has your child been │
│ diagnosed with Alström │
│ Syndrome? │
└──────┬──────────┬───────────┘
│ Yes │ No
▼ ▼
┌──────────┐ Continue below
│ See: │
│ /diagnosis│
│ /symptoms│
│ Newly- │
│ diagnosed │
│ first steps│
└──────────┘If NOT yet diagnosed: How old is your child?
┌──────────────────────────────────────────┐
│ Child's age? │
└──┬───────────┬────────────┬──────────────┘
│ 0–2y │ 3–14y │ 15+y / adult
▼ ▼ ▼
PATH A PATH B PATH CPATH A — Child age 0–2 years
┌────────────────────────────────────────────────────┐
│ Has your baby had any of: │
│ • Severe light sensitivity (cries in normal │
│ indoor light) │
│ • Wobbly/jiggling eyes (nystagmus) │
│ • Unexplained heart failure or cardiomyopathy │
│ • Failure to track or follow objects │
│ in normal lighting │
└──┬───────────────────────────────────────────┬─────┘
│ Yes (one or more) │ No
▼ ▼
┌──────────────────────────────────┐ Less likely Alström
│ These are HIGH-PRIORITY │ but if you have
│ signs that warrant evaluation │ other concerns,
│ for inherited eye/heart │ discuss with your
│ conditions including Alström. │ pediatrician.
└──────────────┬───────────────────┘
▼
┌──────────────────────────────────────────────────┐
│ ASK YOUR PEDIATRICIAN FOR: │
│ 1. Pediatric ophthalmology referral │
│ (request an ERG) │
│ 2. Pediatric cardiology evaluation │
│ (echocardiogram) │
│ 3. Clinical genetics referral │
│ (request ALMS1 testing or │
│ ciliopathy/retinal-dystrophy panel) │
└──────────────┬───────────────────────────────────┘
▼
┌──────────────────────────────────────────────────┐
│ IF ERG SHOWS CONE-ROD DYSTROPHY: │
│ → Genetic testing including ALMS1 is appropriate │
│ → See /blog/early-signs-alstrom-syndrome-babies │
│ → See /blog/cone-rod-dystrophy-alstrom │
│ │
│ IF ECHOCARDIOGRAM SHOWS DILATED CARDIOMYOPATHY: │
│ → Genetic panel for pediatric cardiomyopathy │
│ including ALMS1 │
│ → See /blog/newborn-heart-failure-alstrom │
│ → See /blog/infantile-cardiomyopathy-alstrom │
└──────────────────────────────────────────────────┘PATH B — Child age 3–14 years
┌────────────────────────────────────────────────────────┐
│ Does your child have ANY of these? │
│ • Diagnosed with cone-rod dystrophy or LCA │
│ • Diagnosed with retinitis pigmentosa │
│ • Diagnosed with Bardet-Biedl Syndrome but │
│ no polydactyly or has cardiomyopathy │
│ • History of infant cardiomyopathy │
│ • Progressive hearing loss starting in childhood │
│ • Significant childhood obesity (>95th centile) │
│ • Early signs of insulin resistance (acanthosis │
│ nigricans, dark velvety skin in folds) │
└──┬─────────────────────────────────────────────────┬───┘
│ Yes (one) │ Yes (multiple)
▼ ▼
┌──────────────────────────────┐ ┌──────────────────────────┐
│ Single-system findings │ │ Multiple findings — │
│ warrant evaluation but may │ │ Alström is on the │
│ have other causes. │ │ differential. │
│ Consider whether other │ │ Genetic testing including │
│ systems show subtle signs. │ │ ALMS1 is appropriate. │
└────────────┬─────────────────┘ └─────────────┬────────────┘
▼ ▼
┌────────────────────────────────────────────────────────┐
│ ASK FOR: │
│ • Clinical genetics referral │
│ • Comprehensive panel including ALMS1 │
│ • Echocardiogram if not done recently │
│ • Audiology if hearing concerns │
│ • Fasting glucose and HbA1c if metabolic concerns │
└────────────────────────────────────────────────────────┘PATH C — Adolescent or adult (15+ years)
┌─────────────────────────────────────────────────────────┐
│ Does the patient have: │
│ • Childhood-onset retinal dystrophy or RP │
│ • PLUS childhood-onset hearing loss │
│ • PLUS severe insulin resistance / type 2 diabetes │
│ • PLUS cardiomyopathy (current or in childhood) │
│ • PLUS childhood obesity │
└──┬──────────────────────────────────────────────────┬───┘
│ Yes (combination) │ Some but not all
▼ ▼
┌─────────────────────────────────────────┐ ┌─────────────────────┐
│ Strong combination — ALMS1 testing │ │ Partial │
│ is highly appropriate, even if patient │ │ presentation — │
│ was previously diagnosed with separate │ │ worth evaluation. │
│ conditions (RP + diabetes + cardiac). │ │ Discuss with │
│ │ │ geneticist. │
└────────────┬────────────────────────────┘ └─────────────────────┘
▼
┌──────────────────────────────────────────────────────┐
│ ADULT-ONSET DIAGNOSIS PATHWAY: │
│ • Adult clinical genetics referral │
│ • Targeted ALMS1 sequencing (or comprehensive │
│ panel if uncertainty) │
│ • Multidisciplinary review of current health │
│ status across systems │
│ • Connection to patient organizations and │
│ potential center-of-excellence visit │
└──────────────────────────────────────────────────────┘What if you've checked and your child doesn't fit Alström?
Many children with one or two of these features have other conditions, not Alström. Conditions on the differential to discuss with your team:
- Leber Congenital Amaurosis — isolated retinal dystrophy
- Other inherited retinal dystrophies — many genetic causes
- Bardet-Biedl Syndrome — polydactyly, intellectual disability, more variable
- Usher Syndrome — hearing + vision but no cardiomyopathy
- Wolfram Syndrome (DIDMOAD) — diabetes insipidus and optic atrophy
- Cohen Syndrome — intellectual disability, characteristic features
- Joubert Syndrome — neurological involvement
- Meckel-Gruber Syndrome — multisystem ciliopathy
- Other genetic cardiomyopathies — many genes
A comprehensive ciliopathy panel or whole-exome sequencing is the most efficient way to sort through the differential.
For clinicians — clinical decision tree
Step 1 — When to consider Alström Syndrome
Consider in any patient with:
Pediatric patients:
- Nystagmus + photophobia in infancy (with or without other findings)
- Confirmed cone-rod dystrophy on ERG
- Unexplained dilated cardiomyopathy in infancy
- Cone-rod dystrophy + childhood obesity
- Cone-rod dystrophy + childhood-onset insulin resistance/diabetes
- Bilateral progressive sensorineural hearing loss + retinal disease
- Bardet-Biedl-like presentation without polydactyly or intellectual disability
Adult patients:
- Long-standing visual loss attributed to RP + childhood obesity
- Severe insulin resistance + retinal degeneration
- Cardiomyopathy + retinal disease
- Multi-system disease with diabetes + sensory loss + cardiac
- Adult diagnosed with separate conditions that might fit a single multisystem diagnosis
Step 2 — Initial workup
For suspected Alström, baseline workup includes:
| Specialty | Tests |
|---|---|
| Ophthalmology | ERG, OCT, fundus exam, visual fields, visual acuity |
| Cardiology | Echocardiogram, EKG, sometimes cardiac MRI |
| Audiology | Audiogram, OAE, tympanometry, ABR (in young children) |
| Endocrinology / Metabolic | Fasting glucose, HbA1c, fasting insulin, lipid panel, thyroid function |
| Hepatology | LFTs, abdominal ultrasound |
| Nephrology | Creatinine, eGFR, urinalysis with microalbumin |
| Genetics | Targeted ALMS1 sequencing, or comprehensive ciliopathy panel, or whole-exome sequencing as appropriate |
Step 3 — Genetic testing strategy
┌──────────────────────────────────────────────────────────┐
│ CLINICAL PRESENTATION │
└─────┬─────────────────────────────────┬──────────────────┘
│ Strong Alström suspicion │ Differential is broad
▼ ▼
┌─────────────────────┐ ┌──────────────────────────┐
│ Targeted ALMS1 │ │ Comprehensive panel: │
│ sequencing (all │ │ • Retinal dystrophy │
│ exons + splice │ │ panel │
│ junctions) PLUS │ │ • Ciliopathy panel │
│ deletion/duplication │ │ • Cardiomyopathy panel │
│ analysis │ │ (depending on focus) │
└──────────┬───────────┘ └──────────────┬───────────┘
│ │
▼ ▼
┌─────────────────────────────────────────────────┐
│ RESULT INTERPRETATION: │
│ • Two pathogenic ALMS1 variants → Diagnosis │
│ confirmed │
│ • One pathogenic + one VUS → segregation │
│ studies, possible reanalysis │
│ • Negative or inconclusive → consider │
│ whole-exome sequencing, alternative diagnoses │
└─────────────────────────────────────────────────┘Step 4 — Diagnostic criteria check
Apply the 2020 international consensus criteria (Tahani et al.) stratified by age:
Birth–2 years:
- Possible: 2 minor criteria
- Probable: 1 major + 1 minor
- Definite: 2 major OR 1 major + genetic confirmation
3–14 years:
- Probable: 1 major + 2 minor
- Definite: 2 major
15+ years:
- Probable: 1 major + 4 minor
- Definite: 2 major + genetic confirmation
Major criteria: ALMS1 mutations / family history / cone-rod dystrophy Minor criteria: obesity, cardiomyopathy, hearing loss, hepatic, renal, insulin resistance/T2DM, hypertriglyceridemia, short stature, hypogonadism, pulmonary, urologic, developmental delay, scoliosis, acanthosis nigricans
Step 5 — After diagnosis confirmation
Once Alström is confirmed:
1. Multidisciplinary baseline workup if not already complete
2. Surveillance schedule per 2020 consensus guidelines
3. Family member counseling and testing as appropriate
4. Connection to patient organizations (ASI, ASUK)
5. Center-of-excellence consultation when feasible
6. Documentation in registries for research participation
A common diagnostic puzzle: distinguishing Alström from related conditions
| Feature | Alström | Bardet-Biedl | Usher | LCA |
|---|---|---|---|---|
| Genes | ALMS1 only | BBS1–BBS22+ | USH1A, USH2A, others | Multiple |
| Polydactyly | No | Common | No | No |
| Intellectual disability | Typically not | Common | No | Variable |
| Cardiomyopathy | Common | Rare | No | No |
| Obesity | Severe, early | Common | No | No |
| Insulin resistance / T2DM | Severe, near-universal | Common | No | No |
| Hearing loss | First decade | Less common | Variable timing | No |
| Retinal phenotype | Cone-rod dystrophy | Cone-rod dystrophy | Rod-cone (RP) | Variable |
| Photophobia | Severe, early | Variable | No | Variable |
| Nystagmus | Yes (infantile) | Variable | Variable | Yes |
| Renal | Slow nephropathy | Structural malformations | No | No |
| Hepatic | NAFLD common | Less common | No | No |
Decision summary card (1-page printable)
═══════════════════════════════════════════════════════════════ ALSTRÖM SYNDROME — WHEN TO SUSPECT IT ═══════════════════════════════════════════════════════════════ ANY OF THESE SHOULD PROMPT EVALUATION: ❒ Severe photophobia + nystagmus in infancy ❒ Cone-rod dystrophy on ERG (any age) ❒ Unexplained dilated cardiomyopathy in infancy ❒ Cone-rod dystrophy + childhood obesity ❒ Cone-rod dystrophy + early T2DM ❒ Bilateral progressive SNHL + retinal disease ❒ Adult RP + severe insulin resistance + cardiomyopathy NEXT STEPS: 1. Detailed history including family history 2. Physical exam noting growth, dysmorphology, signs of metabolic syndrome (acanthosis nigricans) 3. Baseline labs: glucose, HbA1c, insulin, lipids, LFTs, kidney function 4. Echocardiogram and EKG 5. ERG, OCT, fundus exam 6. Audiogram if any hearing concern 7. CLINICAL GENETICS REFERRAL with request for ALMS1 testing or comprehensive panel GENETIC TESTING OPTIONS: □ Targeted ALMS1 sequencing □ Retinal dystrophy panel including ALMS1 □ Ciliopathy panel □ Pediatric cardiomyopathy panel □ Whole-exome sequencing PATIENT RESOURCES: - ASI: alstrom.org - ASUK: alstrom.org.uk - MyAlstrom (family-facing): myalstrom.com - GeneReviews: ncbi.nlm.nih.gov/books/NBK1267/ - 2020 Consensus Guidelines: Tahani et al., Orphanet J Rare Dis. 2020;15(1):253 ═══════════════════════════════════════════════════════════════
When this flowchart isn't enough
The flowcharts above cover common patterns. They don't cover every clinical scenario. For unusual presentations or when uncertainty persists:
- Refer to clinical genetics — the right specialty for sorting out rare conditions
- Connect with a center of excellence — the GBMC team, the Indiana team, the Birmingham UK team, the ERN-EYE network, and others have seen unusual cases
- Patient organizations — ASI and ASUK can sometimes facilitate clinical consultation through their networks
Frequently Asked Questions
Is this flowchart medically reviewed?
Yes — by [Medical Reviewer Name and Credentials, to be added before publication]. Updated periodically as guidelines and research evolve.
Can I show this to my pediatrician?
Yes. The flowchart is designed to support conversation, not replace medical judgment.
What if my doctor doesn't think Alström is possible?
Most pediatricians have never seen a case. If your child has a combination of features that fits Alström and your doctor isn't moving toward genetic testing, ask for a clinical genetics referral specifically.
Where can I find more information?
The full diagnosis pillar at /diagnosis covers the diagnostic process in depth. The articles linked from each step provide more detail on specific topics.
This flowchart is for informational purposes only and is not a substitute for clinical judgment. Final diagnostic decisions belong with the medical team.
Last updated April 30, 2026.