FLG and ichthyosis vulgaris: However, this potential equivalence needs to be validated by detailed molecular cell biology comparisons, including the confirmation in African elephants of two key markers of ichthyosis vulgaris in humans6: the lack of keratohyalin granules in the lower stratum corneum and a substantial decrease in the expression of profilaggrin, a precursor of the protein filaggrin involved in the aggregation of keratin filaments.