Hurler syndrome is one of a rare group of inherited diseases known as mucopolysaccharidoses. In this syndrome the body is unable to break down long chains of sugar molecules called glycosaminoglycans, or mucopolysaccharides. The molecules are found throughout the body, often in mucus and in fluid around the joints. Because the body is unable to make an enzyme called lysosomal alpha-L-iduronidase, the sugar molecules build up and accumulate in blood cells, cartilage, bone and connective tissues leading to permanent damage in multiple body organs. Hurler syndrome is the most severe type of mucopolysaccharidosis. Symptoms can range from mild to severe. Symptoms include: abnormal bones in the spine, claw hand, cloudy corneas, deafness, halted growth, heart value problems, joint disease, including stiffness, mental retardation that gets worse over time, thick, coarse facial features with low nasal bridge . Symptoms of Hurler syndrome most often appear between ages 3 and 8. Some individuals have skeletal and joint deformities that affect mobility.
TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Definitive diagnostic lab testing: Genetic testing for mutations in the alpha-L-iduronidase (IDUA) gene. X-rays of the spine showing dysostosis multiplex; Urine testing may reveal excess glycosaminoglycans (heparin sulfate/ dermatan sulfate); Echocardiogram; pulmonary function testing; EMG/ NCS nerve conduction studies; CT scan/ MRI may be supportive. Slit lamp examination.
Physical findings: Distinct facial features (flat face, depressed nasal bridge, bulging forehead), short stature, enlarged tongue (macroglossia) and vocal cords, clouding of corneas, joint stiffness, claw hand, enlarged liver and spleen, leaky heart valves/ enlarged heart, umbilical and inguinal hernia, carpal tunnel syndrome, hydrocephalus (build up of fluid around brain), macrocephaly (large head) and cervical spinal stenosis (narrowing of spinal cord).
ICD-9: 277.5 Mucopolysaccharidosis
ONSET AND PROGRESSION
Infants may appear normal at birth. Signs most often appear between the ages of 6 and 24 months. The severe form is associated with rapid progression and decreases in intellectual functioning, developmental delay and/ or regression, and death occurs by age 10. Heart disease and pulmonary complications are the major causes of death.
Suggested MER for Evaluation: Clinical examination that describes diagnostic features of the impairment including physical examination of the eyes, heart, respiratory system, liver and spleen and laboratory studies are needed to confirm the diagnosis. Laboratory tests showing results of genetic testing for mutations in the IDUA gene, evidence of neurodevelopmental delay.