Last updated 2mo ago
A boy has features similar to Hurler but without corneal clouding. He has distinctive ivory-colored skin lesions (pebbling) on the upper back and shoulders.
XLR; IDS (iduronate-2-sulfatase)
- Similar to MPS I but no corneal clouding
- Pebbled skin lesions (pathognomonic)
- Only X-linked MPS
- Severe and attenuated forms
- On RUSP (some states)
- Urine glycosaminoglycans: elevated dermatan sulfate and heparan sulfate
- Deficient iduronate-2-sulfatase enzyme activity (with a second sulfatase assay normal, to exclude multiple sulfatase deficiency)
- IDS molecular testing confirms diagnosis and identifies carriers (X-linked); useful for the large recurrent inversion/rearrangement
- Enzyme replacement therapy (idursulfase), HSCT
"Hun-Two-er" = MPS II: "Two" is hidden in "Hun-Two-er" (Hunter).
"Hunter sees clearly": Hunter syndrome (MPS II) has no corneal clouding (unlike Hurler). The hunter needs clear vision to aim. "Hunter ate the prey": iduronate-2-sulfatase removes a sulfate group.
"Hunt with Rocks/Pebbles": pebbled skin lesions on the upper back and shoulders are pathognomonic for MPS II. "Hunt Deer": Hunter has heparan + dermatan sulfate elevated in urine.
Only X-linked MPS: part of the HALO-M X-linked disorders: Hunter, Adrenoleukodystrophy, Lesch-Nyhan, OTC deficiency, Menkes.