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This is an interesting disease that doesn’t come up conversationally or in medical school lectures too often, but it is in fact tested on USMLE Step1. This is because its pathophysiology relates to collagen synthesis, which is exceedingly HY on Step1.
Inheritance pattern and mechanism of disease
- Menkes syndrome (XR) and Wilson disease (AR) are essentially the opposite, where the latter is too much copper and the former too little.
- Menkes is characterized by a decreased ability to absorb copper in the gut due to a defective transporter (ATP7A).
- Wilson is due to an inability to secrete copper into bile (copper is normally excreted through bile).
Why we need copper
- It is a cofactor for lysyl oxidase, which is the final enzyme necessary in collagen synthesis.
- This means there is lesser activity of lysyl oxidase in Menkes syndrome secondary to copper deficiency.
| On the USMLE, Menkes syndrome will present very similarly to vitamin C deficiency (scurvy). So be on the lookout and have Menkes syndrome as a DDx. |
Menkes syndrome is characterized by connective tissue weakness, brittle, “kinky” hair, neurological disorders (including truncal hypotonia and seizures) and mental impairment.
| By far the most important thing to remember about Menkes disease is the “kinky” hair. |
That’s it.
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