Femoral head pathology in Sanfilippo disease.

Sanfilippo syndrome (MPS III) is a lysosomal storage disorder consisting of
four different subtypes, depending on the deficient enzyme in the degradation
of the glycosaminoglycan (GAG) heparan sulfate (HS). The disease is
characterized by progressive and severe neurodegeneration. The clinical course
does not differ between the four subtypes.

The somatic signs and symptoms of the disease are mild compared to the severe
central nervous system damage. However, in the recent years we have diagnosed
moderate to severe femoral head abnormalities, resembling avascular femoral
head necrosis (AVN), in several young patients with Sanfilippo disease, all
presenting with signs of hip pain. AVN was previously reported in MPS III
patients (REF!) but the prevalence of this symptom in MPS III patients is not
known.

As cognition and communication are almost invariably severely affected in
patients with MPS III it can be very difficult to assess if *discomfort* in a
patient with MPS III is due to hip pain or to other somatic or non-somatic
causes. As a consequence, the prevalence of femoral head disease is probably
underestimated. This may result in inadequate care and treatment.

To evaluate the prevalence of femoral head pathology in patients with MPS III.

Approximately 40 patients with confirmed MPS III will participate in the study.
The study will take 6 months. From each patient two X-rays of the hip will be
taken. Also length, weight and a history of pain and discomfort or problems in
relation of hipfunction will be reported by a questionnaire.
These X-rays will be evaluated on femoral head pathology by a radiologist.

Radiation exposure, and incidences occurring while performing the X-rays,
because of unexpected movements of the patient.