What is Alstrom-Hallgren Syndrome?
Alstrom-Hallgren Syndrome is a very unique genetic disorder. Only about 266 cases have been reported in 47 countries. It is named after Carl-Henry Alstrom and B. Halllgren, who were the first to describe Alstrom-Hallgren Syndrome. Alstrom syndrome is caused by mutations in the ALMS1 gene. It is inherited as an autosomal recessive trait, which means that the child inherits the defective ALMS1 gene from both the carrier parents. A child is 25% likely to be affected by it if both the parents have the carrier gene. Both males and females are equally likely to carry the gene. It is characterized by progressive loss of vision and hearing, weakening of cardiac muscles, obesity, and type-2 diabetes. Children generally face learning difficulty, although intelligence is not affected. No specific treatment is available for Alstrom-Hallgren Syndrom, only symptoms can be managed to enhance the quality of life and possibly increase lifespan.
Causes of Alstrom-Hallgren Syndrome
Alstrom-Hallgren syndrome is caused by a faulty ALMS1 gene. A gene is a physical and functional unit of heredity. Genes are responsible for the creation of proteins, which play vital roles in our body. A defective or mutated gene may produce a faulty, inefficient protein that may affect multiple organ systems, including the brain. The function of the protein made by the ALMS1 gene is unknown, probably involved in ciliary function, cell cycle control, and intercellular transport. Mutations in this gene are responsible for the production of very short, non-functional ALMS1 protein. These proteins are found in most of the tissues in small amounts, which explain why Alstrom syndrome affects multiple parts of the body. Environmental factors may also be responsible to some extent, as some researchers believe.
Diagnosis of Alstrom-Hallgren Syndrome
Alstrom-Hallgren Syndrome can be diagnosed based on symptoms, family and medical history of the individual. Although it is detectable at infancy, doctors mistake the symptoms as separate individual problems. Hence detection occurs generally much later. Pregnant women should undergo prenatal diagnosis by performing Amniocentesis or Chorionic villus. A physical examination is generally done to properly test the patient. Various imaging techniques like computerized tomography scans (CT), Magnetic Resonance Imaging (MRI) or X-ray is done to see internal body structures. Genetic testing is performed to identify genetic disorders, but it is quite expensive. Symptoms of Alstrom-Hallgren Syndrome vary among different age groups. Hence the diagnostic is age specific.
- For a child less than 2 years of age, family history is studied to identify the possible mutation of the ALMS1 gene. Vision defects and minor criteria like obesity is usually studied
- For children of age between 3 and 14 years, 2 major criteria along with 1 minor criterion or 1 major and 3 minor criterion like hearing loss, bone density loss are studied.
- Adults, more than 15 years, 2 major and 2 minor criteria are studied. Legal blindness, irregular menstruation, hormonal imbalance, dwarfism, etc. are studied.
Signs and Symptoms of Alstrom-Hallgren Syndrome
Alstrom-Hallgren syndrome can affect many different parts of the body. The symptoms and their severity, progression varies greatly among individuals, even in the same family
- The first vision-related symptoms of Alstrom-Hallgren syndrome are observed in babies, having high sensitivity to light along with rapid eye movement, called “photophobia” and “nystagmus” due to the degradation of the retina. The photoreceptors in the eye responsible for color vision deteriorate, an eye condition called cone-rod dystrophy. Vision decreases throughout childhood to almost nil by late teen years.
- Due to loss of nerve function, auditory information fails to get into the brain for processing resulting in “sensorineural” or hearing loss. Hearing aids like Cochlear implants are beneficial.
- People suffering from Alstrom-Hallgren Syndrom are generally overweight. After puberty, they generally have shorter stature than their peers.
- The myocardium, which forms the walls of the heart chamber, weakens. Cardiac muscles become enlarged, a condition called “dilated cardiomyopathy.” This leads to difficulty in pumping operations, fluid and blood build up in lungs, swelling of feet and legs. This is called “congestive heart failure.” This results in shortness of breath, fatigue and diminished stamina and even heart failure.
- Affected people often have learning disabilities due to their poor vision and hearing, although intelligence is not affected. Development milestones like crawling, walking is delayed. Children find it difficult to develop language nuances, which affect their overall learning.
- Children or teens suffering from Alstrom-Hallgren Syndrome are often unable to process insulin the way they should. The pancreas secretes insulin to regulate blood sugar levels. The patient’s suffering from Alstrom-Hallgren Syndrome fails to react to insulin. As a result, hyperinsulinemia is observed. Insulin resistance promotes the development of type 2 diabetes, even among young children. The excessive urge to urinate and increased thirst, are indicators of Alstrom-Hallgren Syndrome.
- Higher than normal levels of fats like cholesterol and triglycerides are present in the blood.
- Teens may experience delayed puberty due to diminished hormone production by testes. Some males develop enlarged breasts.
- Liver and kidney failures are also common among patients.
Prevention of Alstrom-Hallgren Syndrome
Prevention of Alstrom-Hallgren Syndrome is difficult since it is an inherited disorder. People with a family history of Alstrom-Hallgren Syndrome can appear for genetic testing and counseling to discuss the probability of having children suffering from such conditions. Genetic counselors perform tests like chorionic villus sampling (CVS), Preimplantation genetic diagnosis (PGD) and amniocentesis to track the defective ALSM1 gene and predict risks associated with it. With PGD, embryos can be tested for the said defective gene and the unaffected embryos can be selectively implanted via in vitro fertilization. It is important for parents to anticipate these symptoms in their child as early as possible and seek medical consultation before they turn absolutely incurable.
Treatment for Alstrom-Hallgren Syndrome
There is no particular cure for Alstrom-Hallgren Syndrome. However, treatments to lessen the symptoms of Alstrom-Hallgren Syndrome greatly help to improve the quality of life and prevent complications in the future.
In the case of weak eyesight, corrective lenses can be used. Tinted lenses can reduce the power from bright lights. In the case of complete blindness, patients should be slowly prepared to learn Braille or similar skills. Hearing aids like cochlear implants can be used to cope up with the hearing loss. An appropriate balanced diet is mandatory for the patients since they have a high risk of turning obese or diabetic. Exercise also reduces the chances of obesity. A balanced diet and regular exercise keep a check on the blood sugar levels, reducing the chances of diabetes. Dialysis restores the filtering functions since most of the patients have weak kidney. Hemodialysis circulates blood into an external filter to clean it and returns the filtered blood back to the body. Peritoneal dialysis introduces dextrose containing fluid in the abdomen by a tube, which takes away the wastes from the body. The solution can then be removed from the patient’s body. In the case of kidney failure, patients may have to go through a kidney transplant. Kidneys can be maintained using ACE inhibitors. In the case of severe scoliosis, surgery may be needed.
Patients suffering from Alstrom-Hallgren Syndrom are more vulnerable to lung infections like bronchitis. Antibiotics can be prescribed to them. Oral medications can be taken to treat diabetes, usually once or twice daily before a meal. Drugs like Meglitinides, Metformin, Thiazolidinediones and injected diabetes medicines like Pramlintide and Exenatide have been found to be very effective. Cholesterol-lowering medicines like HMG-CoA effectively lower lipoprotein, cholesterol and triglyceride levels. Angiotensin-converting enzyme (ACE) inhibitors, diuretics, and beta blockers reduce the chances of heart failure. Bladder and Urine flow can be coordinated with self-catheterization. In the case of irregular menstruation, Estroprogestin can be prescribed.
Prognosis of Alstrom-Hallgren Syndrome
Early diagnosis and intervention is the best way to halt the progression of the symptoms of Alstrom-Hallgren Syndrome and improve the quality of life of patients. Prognosis of Alstrom-Hallgren Syndrome is difficult because the symptoms vary widely among patients. Weak hearing and eyesight may lead to permanent blindness and deafness if left untreated. Type 2 diabetes is very common among patients. Liver and kidney failure are likely to worsen with age. Due to such varied complicated symptoms, life expectancy is greatly reduced. Most of the Alstrom-Hallgren Syndrome patients do not live beyond 50 years.
Alstrom-Hallgren Syndrome is a rare but complex genetic disorder that affects multiple functions of the body. Unfortunately, there is no particular treatment of Alstrom-Hallgren Syndrome. Symptom targeted treatments are the only option to recover. The best way is to deal with it is to detect it as early as possible and start the required treatment to reduce the chances of complications.
- Joy, T., Cao, H., Black, G., Malik, R., Charlton-Menys, V., Hegele, R., & Durrington, P. Alstrom syndrome (OMIM 203800): a case report and literature review. Orphanet Journal Of Rare Diseases, (2007). 49. doi: 10.1186/1750-1172-2-49