Case study 1: Julian
- Julian suffers from pain in his back, hips, and hands
- He has had back ache since he was 2 years old
- The pain in his hips started about five years ago
- Julian has also recently started to have pain in his hands
- The physician referred Julian for X-ray imaging of his spine and pelvis. In addition, the physician requested a number of laboratory tests
Patient file
Table 1: Patient characteristics and observations from physical examination
Age | 16 years |
Height | 183 cm (90th percentile) |
Weight | 69 kg (75th percentile) |
Eyes | Signs of early posterior subcapsular cataract formation |
Cognitive function | Normal for age |
ECG/ECHO | Normal for age |
Nerve conduction test for carpal tunnel syndrome | Normal |
X-ray findings

Figure 1:
Pelvis. Note the flattened appearance and the uncovered position of both femoral heads1

Figure 2:
Lateral spine. Note the anterior beaking of the thoracic and lumbar vertebral bodies1
- How do you interpret these findings?
- When examining these test results, would you consider a diagnosis of MPS?
Table 2: Medical examinations
Test | Results | Reference ranges2 |
---|---|---|
Pulmonary function test | Forced vital capacity = 85% Forced expiratory volume in 1s = 88% | 71.7 – 127.3% 75.8 – 128.2% |
6-min walk test | 570 m | 570 – 790 m |
Abdominal ultrasound | Liver and spleen: normal size | - |
Interpretation:
- Julian’s radiologic findings demonstrate features often found in MPS, including uncovering of the femoral heads and anterior beaking in the spine
- Julian’s bone pain, together with the atypical radiologic findings, prompted the physician to refer Julian for laboratory tests for urinary GAG levels and leukocyte arylsulfatase B (ASB) activity
Table 3: Laboratory test results
Test | Results | Reference ranges1 |
---|---|---|
Urinary GAG/creatinine ratio | 58.4 mg/g | Normal values are < 70.7 mg/g |
2-D electrophoresis of extracted GAG (fraction of total GAG) | Dermatan sulfate = increased but below level of chondroitin sulfate | – |
Leukocyte ASB activity | 0.07 µmol/g/hr | Normal control: 24.3 µmol/g/hr |
Diagnosis
- Because of the abnormal X-ray findings, MPS was considered as a possible diagnosis
- Subsequent laboratory tests showed abnormal urinary GAG electrophoresis and deficiency of ASB in leukocytes. A diagnosis of MPS type VI was made
- Diagnosis was subsequently confirmed with mutation analysis which detected homozygosity for the p.Y210C mutation in the N-acetylgalactosamine-4-sulfatase gene (ARSB). This is the most prevalent MPS VI mutation, detected in 18% of patients2
- Harangi F, et al. Pediatr Nephrol 1996;10:555–558.
- Reprinted from Molecular Genetics and Metabolism, volume 103;Gottwald I, Hughes J, Stewart F, Tylee K, Church H, Jones SA. ©2011, with permission from Elsevier.
- Reprinted from Molecular Genetics and Metabolism, volume 103;Gottwald I, Hughes J, Stewart F, Tylee K, Church H, Jones SA. ©2011, with permission from Elsevier.
- Li AM, et al. Am J Respir Crit Care Med 2007;176:174–180.