In their comments on our earlier editorial,1 Küster et al provide further valuable information that may help to resolve the issue regarding the endogenous-vs-exogenous origin of epidermal n-alkanes. They now provide biochemical data on two phenotypic subgroups of autosomal recessive ichthyosis, which do not differ in their content of n-alkanes, although the alkane content of both subsets was greater than the normal subsets. We agree with the authors that photodensitometric quantitation underestimates n-alkanes of shorter chain lengths due to the volatilization of shorter chain n-alkanes during the charring procedure. Since approximately half of scale n-alkanes will have a chain length less than or equal to C25,2 the true values for n-alkanes in both of their subgroups as well as in their normal subgroups are likely to be considerably higher. Thus, we believe that laboratories that rely solely on photodensitometry
Elias PM, Williams ML. n-Alkanes in the Skin-Reply. Arch Dermatol. 1991;127(11):1728. doi:10.1001/archderm.1991.01680100131022
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