I didn't know that the two subgroups for EHK had even more categories. I found this article online today and thought you might be interested. If you already know this stuff, sorry for boring you [img]http://www.ichthyosis.com/ubb/smile.gif
In 1994, DiGiovanna and Bale separated the various clinical presentations of EHK into 2 primary types, including NPS (without severe palm/sole hyperkeratosis) and PS (with severe palm/sole hyperkeratosis) based on the presence or absence of severe palmoplantar hyperkeratosis. The 2 primary types were subdivided further into 3 subtypes each depending on the clinical presentations. Some of the subtypes have general involvement, while others are localized only.
NPS subtypes do not have severe palmoplantar involvement. Distinctions between the 3 NPS subtypes are based on different clinical presentations.
NPS-1 has normal palmoplantar surfaces, no digital contractures, a hystrix scale, a generalized skin distribution, no history of erythroderma, a positive history of blistering, and patients may have abnormal gait.
NPS-2 is similar to NPS-1. The only differences are a brown scale instead of a hystrix scale and a lack of gait abnormalities.
NPS-3 has no palmoplantar hyperkeratosis, no digital contractures, and is generalized in skin distribution similar to NPS-1 and NPS-2. In contrast, the palmoplantar surface in NPS-3 is hyperlinear, has minimal scale, and a thin white scale is most prominent on the trunk. Erythroderma is mild to moderate. NPS-3 may have gait abnormalities similar to NPS-1.
PS subtypes have severe palmoplantar involvement. The 3 subtypes are differentiated based on clinical presentations.
PS-1 has smooth palmoplantar hyperkeratotic surfaces, no digital contractures, a localized distribution of skin involvement (limited flexural involvement, truncal sparing), no erythroderma, a localized blistering, and no gait abnormalities.
PS-2 has smooth palmoplantar hyperkeratotic surfaces but has digital contractures, generalized skin involvement with hyperkeratosis most severe over the joints at both flexor and extensor surfaces, mild-to-moderate erythroderma, positive blistering, and may have gait abnormalities.
PS-3 has cerebriform palmoplantar surfaces, no digital contractures, a tan scale, generalized skin involvement, no erythroderma, neonatal blistering, and no gait abnormalities.
Causes: Defects in genes for keratin 1 and 10 are the cause of EHK. Defects in keratin 1 are associated with the PS variants; defects in keratin 10 are associated with the NPS variants.