Alström syndrome

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
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Alström syndrome
Synonyms	ALMS
Pronounce
Specialty	Medical genetics
Symptoms	Blindness, deafness, obesity, type 2 diabetes, cardiomyopathy
Complications	N/A
Onset	Childhood
Duration	Lifelong
Types	N/A
Causes	Mutations in the ALMS1 gene
Risks
Diagnosis	Genetic testing, clinical evaluation
Differential diagnosis	Bardet-Biedl syndrome, Usher syndrome
Prevention	None
Treatment	Symptomatic management
Medication
Prognosis	Variable, often reduced life expectancy
Frequency	Rare
Deaths

Other Names: ALMS; ALSS; Alstrom's syndrome; Alstrom syndrome 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. In childhood, the disorder is generally characterized by vision and hearing abnormalities, childhood obesity, and heart disease (cardiomyopathy). Over time, diabetes mellitus, liver problems, and slowly progressive kidney dysfunction which can lead to kidney failure may develop.

Epidemiology

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

Cause

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

Autosomal recessive inheritance, a 25% chance

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.

Affected people inherit one mutated copy of the gene from each parent, who is referred to as a carrier. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). When 2 carriers of an autosomal recessive condition have children, each child has a: 25% (1 in 4) chance to be affected 50% (1 in 2) chance to be an unaffected carrier like each parent 25% (1 in 4) chance to be unaffected and not be a carrier

Signs and symptoms

The signs and symptoms of Alström syndrome vary among affected individuals. The age that symptoms begin also varies. Symptoms may first appear anywhere from infancy to early adulthood. Signs and symptoms may include:

• Vision abnormalities, specifically cone-rod dystrophy and cataracts
• Progressive sensorineural hearing loss in both ears and chronic infection or inflammation of the middle ear
• Heart disease that enlarges and weakens the heart muscle (dilated cardiomyopathy)
• Excessive eating (hyperphagia) and rapid weight gain leading to obesity
• Insulin resistance leading to high levels of insulin in the blood (hyperinsulinemia) and type 2 diabetes mellitus
• Elevated levels of fats (lipids) in the blood (hyperlipidemia)
• Fatty liver that may progress to significant liver disease
• Short stature
• Skin findings including abnormally increased coloration and “velvety” thickening of the skin in certain areas of the body (acanthosis nigricans)
• Lower hormone levels produced by the male testes or the female ovaries (hypogonadism)

Alström syndrome can also cause serious or life-threatening medical problems involving the liver, kidneys, bladder, and lungs.

Diagnosis

Alström syndrome is diagnosed based on clinical findings (signs and symptoms), medical history, and family history. Making a diagnosis can be complicated by the variation in age of symptom onset from one individual to another. Genetic testing is not necessary to make the diagnosis of Alström syndrome, although it can be useful to confirm a diagnosis. Genetic testing of the ALMS1 gene is available for Alström syndrome. Although genetic testing is not necessary to make a diagnosis of Alström syndrome, it can be helpful to confirm a diagnosis. If a mutation is not identified in both copies of the ALMS1 gene of an individual suspected to have Alström syndrome, it does not rule out the diagnosis.

Treatment

There is no specific treatment for Alström syndrome. Treatment is focused on managing the symptoms present in each individual. This may involve a team of specialists including but not limited to: pediatricians, cardiologists, audiologists (hearing specialists), ophthalmologists, endocrinologists, and orthopaedists. Treatment may include: Specially-tinted, prescription glasses and vision aids to assist with vision loss

• Hearing aids and cochlear implants for hearing loss
• Dietary measures, exercise programs, and oral medications and/or insulin to control diabetes
• ACE inhibitors and other medications to manage heart and kidney problems with some individuals requiring a kidney or heart transplant
• Hormone therapy if the male testes or female ovaries produce lower than average levels.

Prognosis

The prognosis for Alström syndrome varies depending on the progression of symptoms, specifically heart and kidney disease. The lifespan and overall quality of life for individuals with Alström syndrome can be improved by early diagnosis, treatment, surveillance, and proper management of symptoms.

NIH genetic and rare disease info

• NIH info on Alström syndrome

Alström syndrome is a rare disease.

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