What is Hurler syndrome?
It is an inherited disorder in which a deficiency of alpha-L-iduronidase leads to excessive accumulation of glycosaminoglycans/mucopolysaccharides. It has been named after Gertrud Hurler who was a renowned German Pediatrician and medical practitioner. This condition is one of the several forms of mucopolysaccharidoses, a group of metabolic disorders caused by a lack of some lysosomal enzymes involved in the breakdown of glycosaminoglycans. The following are some of the other names of the disorder:
Mucopolysaccharidosis type 1
Hurler syndrome Symptoms
Most patients appear healthy and normal at birth without any notable signs of the disorder. However, the symptoms develop in the first year of life. Affected children have a short stature and suffer from hepatosplenomegaly, a condition characterized by an enlarged liver and spleen. The facial features undergo a marked deterioration, which mainly include a low nasal bridge, flat face, and protruding forehead. This is followed by a progressive mental retardation, particularly between the age of 2 and 4, due to brain damage. Development completely stops after a few years giving rise to an array of health issues such as:
Congenital malformation of the umbilicus
Joint pain and stiffness
Carpal tunnel syndrome
Coronary heart disorder
Enlarged tongue and skull
Broad and oar-shaped ribs
Upper respiratory infection
Hurler syndrome Causes
Alpha-L iduronidase is a vital enzyme as it causes degradation of mucopolysaccharides in lysosomes. In the absence of this enzyme, there is an excessive deposition of dermatan sulfate and heparin sulfate in the body. In all likelihood, gargoylism is a genetic disorder since a deficiency of alpha-L-iduronidase results from a defective gene called IDUA on chromosome 4. As the gene produces iduronidase enzyme protein, it has been named IDUA. Recent studies have proved that Hurler’s disease can be linked to nearly 52 different mutations. Sufferers usually carry two non-working copies of the mutant gene, but a carrier of the disease has one normal and one defective copy of the gene. However, the latter produces less alpha-L-iduronidase compared to a normal individual, but does not have any clinical manifestations of the disease.
Hurler syndrome Diagnosis
Some of the common diagnostic tests and exams conducted by physicians include:
Affected patients show elevated levels of dermatan sulfate and heparan sulfate in their urine.
On detailed examination of the blood sample, lymphocytes normally reveal the presence of abnormal cytoplasmic inclusions.
Clinicians can estimate the amount of alpha-L-iduronidase with the aid of synthetic substrates in either isolated leukocytes or cultured fibroblasts.
Deformities in the skeletal system, particularly in the lower spine, are detectable with radiographic testing. It is also used for the diagnosis of dysostosis multiplex.
MRI of the brain can point out the causes of mental deterioration. In a similar manner, an echocardiogram can spot any major cardiac defect. Physiological changes in the ophthalmic nerve sheath and sclera are visible using ultrasound imaging test.
Hurler syndrome Treatment
It is highly essential for the healthcare professionals to provide appropriate treatment as well as support to the ailing patients. Joint problems and skeletal deformities may receive orthopedic interventions to improve mobility. Surgical incision in the eardrum can correct hearing impairment. In order to avoid complications, surgery has also been recommended for all inguinal hernias. Ear infections caused by pharyngeal tonsils needs to be excised for better outcomes. Some patients may have to undergo corneal transplants. Affected individuals who do not have any neurological deficits can go for enzyme replacement therapies. Few physical deformities and neurologic symptoms can be improved with the aid of umbilical cord blood transplantation and bone marrow transplantation. According to some medical experts, gene therapy could be used as an effective treatment procedure in the future.
Hurler syndrome Life expectancy
Progressive mental and neurological degeneration leads to death by the age of 10 years. Surprisingly, the other types of mucopolysaccharidoses have a greater life expectancy than this disorder.
Hurler Syndrome Pictures