Alström syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Alström syndrome is a rare condition that affects many body systems. Many of the signs and symptoms of this condition begin in infancy or early childhood, although some appear later in life.

Alström syndrome is characterized by a progressive loss of vision and hearing, a form of heart disease that enlarges and weakens the heart muscle (dilated cardiomyopathy), obesity, type 2 diabetes (the most common form of diabetes), and short stature. This disorder can also cause serious or life-threatening medical problems involving the liver, kidneys, bladder, and lungs. Some individuals with Alström syndrome have a skin condition called acanthosis nigricans, which causes the skin in body folds and creases to become thick, dark, and velvety. The signs and symptoms of Alström syndrome vary in severity, and not all affected individuals have all of the characteristic features of the disorder.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Mutations in the ALMS1 gene cause Alström syndrome. The ALMS1 gene provides instructions for making a protein whose function is unknown. Mutations in this gene probably lead to the production of an abnormally short, nonfunctional version of the ALMS1 protein. This protein is normally present at low levels in most tissues, so a loss of the protein's normal function may help explain why the signs and symptoms of Alström syndrome affect many parts of the body.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

More than 900 people with Alström syndrome have been reported worldwide.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Blindness · Very frequent (99-80%)

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

Hyperlipidemia · Very frequent (99-80%)

The concentration of lipid in the blood circulation is above the upper limit of normal.

Hypertriglyceridemia · Very frequent (99-80%)

The concentration of triglyceride in the blood circulation is above the upper limit of normal.

Insulin resistance · Very frequent (99-80%)

Increased resistance towards insulin, that is, diminished effectiveness of insulin in reducing blood glucose levels.

Nystagmus · Very frequent (99-80%)

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Obesity · Very frequent (99-80%)

Accumulation of substantial excess body fat.

Otitis media · Very frequent (99-80%)

Inflammation or infection of the middle ear.

Progressive sensorineural hearing impairment · Very frequent (99-80%)

A progressive form of sensorineural hearing impairment.

Retinal dystrophy · Very frequent (99-80%)

Retinal dystrophy is an abnormality of the retina associated with a hereditary process. Retinal dystrophies are defined by their predominantly monogenic inheritance and they are frequently associated with loss or dysfunction of photoreceptor cells as a primary or secondary event.

Short stature · Very frequent (99-80%)

A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).

Visual loss · Very frequent (99-80%)

Loss of visual acuity (implying that vision was better at a certain time point in life). Otherwise the term reduced visual acuity should be used (or a subclass of that).

Cone/cone-rod dystrophy · Very frequent (99-80%)

Abnormal liver physiology · Frequent (79-30%)

Any functional anomaly of the liver.

Acanthosis nigricans · Frequent (79-30%)

A dermatosis characterized by thickened, hyperpigmented plaques, typically on the intertriginous surfaces and neck.

Other findings in the same source

From: Orphanet

Additional reported features include Cataract (Frequent (79-30%)); Chronic bronchitis (Frequent (79-30%)); Chronic kidney disease (Frequent (79-30%)); Dilated cardiomyopathy (Frequent (79-30%)); Dorsocervical fat pad (Frequent (79-30%)); Elevated circulating hepatic transaminase concentration (Frequent (79-30%)); Elevated gamma-glutamyltransferase level (Frequent (79-30%)); Functional abnormality of the bladder (Frequent (79-30%)); Hypergonadotropic hypogonadism (Frequent (79-30%)); Hyperinsulinemia (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Alström syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Alström syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.