Morquio syndrome is diagnosed through a combination of clinical evaluation, laboratory tests, and genetic analysis.
Diagnostic Methods for Morquio Syndrome
The diagnostic process typically involves the following steps:
1. Clinical Examination
- Physical Assessment: Doctors will perform a thorough physical exam to look for characteristic signs and symptoms of Morquio syndrome, such as skeletal abnormalities (e.g., short stature, spinal deformities, knock knees), corneal clouding, and joint hypermobility.
2. Laboratory Tests
- Urine Tests: A urine test, specifically a urine keratan sulfate test, can help detect elevated levels of keratan sulfate, a type of glycosaminoglycan (GAG), which is often found in individuals with Morquio A syndrome. However, this test is not always reliable, particularly in young children, and can produce false negatives.
- Enzyme Assay (Blood Test): This blood test measures the activity of the GALNS enzyme (galactosamine-6-sulfatase). Significantly reduced or absent enzyme activity is indicative of Morquio A syndrome.
3. Genetic Testing
- Mutation Analysis: Genetic testing involves analyzing the GALNS gene for mutations. Identifying two disease-causing mutations confirms the diagnosis of Morquio A syndrome. This is considered the most accurate method of diagnosis.
Summary Table of Diagnostic Methods
| Diagnostic Method | Description |
|---|---|
| Clinical Examination | Physical assessment for characteristic signs and symptoms. |
| Urine Keratan Sulfate | Measures keratan sulfate levels; can be unreliable. |
| Enzyme Assay (Blood) | Measures GALNS enzyme activity; low activity suggests Morquio A syndrome. |
| Genetic Testing | Identifies mutations in the GALNS gene; confirms the diagnosis. |
It's important to note that diagnosing Morquio syndrome requires a comprehensive approach, often involving multiple diagnostic tests and consultation with specialists.
