What is Alstrom Syndrome?
Alstrom syndrome, caused by harmful genetic changes (mutations) in the ALMS1 gene, is an inherited condition that affects fat cells and tiny hair-like parts of a cell called cilia. The ALMS1 gene produces a protein that is thought to be involved in movement of various molecules inside and outside of the cell, cell division, the proper function of the cilia, and gene regulation. The ALMS1 protein is found in most tissues in the body, and impairment of the protein function results in a range of symptoms. Although severity of symptoms can vary from person to person, even among those in the same family, most individuals develop heart disease, obesity, diabetes, and progressive vision and hearing loss. Most individuals with Alstrom syndrome have normal intelligence, but may have delayed developmental milestones.
Vision loss, caused by progressive retinal dystrophy, begins in infancy and worsens over time, with most individuals eventually losing all ability to see. Eighty-five percent of individuals with the disease will develop hearing loss in both ears that progresses over time. Nearly all individuals with the disease have high fat (lipid) levels which can lead to obesity. Insulin resistance begins in childhood which can result in individuals developing type 2 diabetes mellitus in adolescence. Two-thirds of individuals with Alstrom syndrome also develop a heart disease called dilated cardiomyopathy which causes the heart muscle to enlarge and weaken. Some individuals with Alstrom syndrome may develop liver or kidney disease. Chronic respiratory infections can begin early in childhood and eventually cause various types of lung illnesses. Other symptoms include short stature, curvature of the spine (scoliosis or kyphosis), extra, missing, or mislocated teeth, seizures, and urinary problems.
Alstrom syndrome can also affect sexual development and fertility. Approximately 80% of males with Alstrom syndrome do not produce enough testosterone (male sex hormone) leading to small external genitalia and degeneration of the testes. Females with Alstrom syndrome may begin puberty early, and their menstruation may be abnormal or absent. Females may also have abnormal hair growth, abnormal growth of uterine tissue (endometriosis), or polycystic ovaries. Most individuals with Alstrom syndrome cannot have biological children.
How common is Alstrom Syndrome?
The exact frequency of Alstrom syndrome in the general population is unknown, though estimates range from 1 in 100,000 to less than 1 in 1,000,000. Only about 950 people have been diagnosed worldwide. The frequency is higher in isolated populations or those where marriage between blood relatives (consanguinity) is common.
How is Alstrom Syndrome treated?
There is no cure for Alstrom syndrome, but careful monitoring of vision, hearing, liver, heart, thyroid, and kidney function is important for detecting and treating symptoms early. Young children benefit from red-tinted prescription glasses, development of non-visual language skills, and hearing aids. Cardiac function should be routinely monitored, and patients who develop cardiomyopathy need to take angiotensin-converting enzyme (ACE) inhibitors. Physical exercise is important for weight management. Some patients require insulin, insulin-sensitizing agents, or thiazolidinediones. Patients may also need hormone replacement therapy. Intermittent self-catheterization can help with bladder control. Some patients may need specific medications and treatments to help with liver and kidney problems. Patients and their families benefit greatly from seeking social and emotional support to cope with the isolation that may come with living with a rare and complicated disorder.
What is the prognosis for an individual with Alstrom Syndrome?
Prognosis is highly variable due to the range of disease presentations. Alstrom syndrome is associated with a number of chronic, life-threatening issues, such as congestive heart failure and end-stage renal disease, which are also the two major causes of death. Life expectancy is reduced with this condition and patients rarely live past 40 years of age.