Alström syndrome is a rare genetic disorder that is characterised by a number of features, notably including extreme sensitivity to light, hearing problems, heart problems, obesity and type 2 diabetes.
Most of the features of Alström syndrome are treatable although health complications of the condition are common.
It is estimated that around 200 families in the UK may be affected by Alström syndrome.
Symptoms, features and complications
There are a number of common features of Alström syndrome which include:
- Eye problems: Including retinal degeneration (progressive worsening of vision), nystagmus (involuntary eye movements) and photophobia (extreme sensitivity to light)
- Hearing impairment
- Cardiomyopathy: Disorder of the heart muscle
- Insulin resistance and hyperinsulinemia: Leading to type 2 diabetes
- Hypertriglyceridaemia: Abnormally high triglyceride levels in the blood
- Renal dysfunction: Kidney disorders
Heart and eye problems will often be diagnosed shortly after birth whilst hearing problems usually occur before the age of 10. Children with Alström syndrome will usually gain weight quickly, despite eating healthily and diagnosis of type 2 diabetes within childhood is common.
The features which a child develops, as well as the severity of the symptoms, can vary from child to child.
Additional complications which can follow include:
- Bladder and bowel problems
- Bone and joint problems: Including arthritis
- Hypogonadism (low testosterone levels)
- Polycystic ovary syndrome (PCOS)
- Hypothyroidism: Underactive thyroid function
Causes of Alström syndrome
Alström syndrome is caused by a mutation in the ALMS1 gene.
A mutation in this gene is known to affect a protein related to cilia, minute whiskers which are present on the surface of cells.
If each parent has a mutation in the ALMS1 gene, there is a 1 in 4 chance that each child they have will develop Alström syndrome.
How is Alström syndrome diagnosed?
A diagnosis of Alström syndrome may be made based on presence of the symptoms. If confirmation is needed, genetic testing can be used to identify mutation of the ALMS1 gene.
There is no cure for Alström syndrome and each feature of the condition requires treatment to control.
- Eye problems: Whilst retinal degeneration cannot be treated, extreme sensitivity to light can be treated by wearing dark glasses.
- Hearing impairment: Hearing aids can be used to improve hearing.
- Heart problems: May be treated with medications including digoxin, furosemide, ACE inhibitors and beta-blockers.
- Obesity: Treated through adjustments to physical activity and diet. Low carbohydrate diets have been found to be effective.
- Type 2 diabetes: Lifestyle adjustments as with obesity treatment. If lifestyle changes do not reduce blood glucose levels sufficiently, medications such as metformin or GLP-1 receptor agonists may be prescribed.
- Hypertriglyceridaemia: May be treated with cholesterol modifying drugs such as statins.
- Renal dysfunction: Lifestyle changes and, if necessary, blood pressure and diabetes medications, can help to reduce the risk of kidney failure. If kidney failure develops, kidney transplantation may be advised.