C5AR1 and erythroderma desquamativum: Although no observations on bone malformations in development or bone density have been published in humans carrying C5 deficiency, and this is most probably due to the rarity of such condition and its lethality (i.e., Leiner`s disease, which is particularly fatal if not corrected at infancy) (Guenther, 1983), the relevance of the C5a-C5aR axis in bone formation and regulation of its structure has been confirmed in preclinical studies.