Evolutionary Biology

, Volume 41, Issue 3, pp 388–396

Evidence That Loss-of-Function Filaggrin Gene Mutations Evolved in Northern Europeans to Favor Intracutaneous Vitamin D3 Production

Authors

  • Jacob P. Thyssen
    • Department of Dermato-Allergology, National Allergy Research Centre, Gentofte University HospitalUniversity of Copenhagen
  • Daniel D. Bikle
    • Endocrinology Service, Veterans Affairs Medical Center, and Department of MedicineUC San Francisco
    • Dermatology Service, Veterans Affairs Medical Center, and Department of DermatologyUC San Francisco
Synthesis Paper

DOI: 10.1007/s11692-014-9282-7

Cite this article as:
Thyssen, J.P., Bikle, D.D. & Elias, P.M. Evol Biol (2014) 41: 388. doi:10.1007/s11692-014-9282-7

Abstract

Skin pigmentation lightened progressively to a variable extent, as modern humans emigrated out of Africa, but extreme lightening occurred only in northern Europeans. Yet, loss of pigmentation alone cannot suffice to sustain cutaneous vitamin D3 (VD3) formation at the high latitudes of northern Europe. We hypothesized that loss-of-function mutations in the epidermal structural protein, filaggrin (FLG), could have evolved to sustain adequate VD3 status. Loss of FLG results in reduced generation of trans-urocanic acid, the principal endogenous ultraviolet-B (UV-B) filter in lightly-pigmented individuals. Accordingly, we identified a higher prevalence of FLG mutations in northern European populations when compared to more southern European, Asian and African populations that correlates significantly with differences in circulating 25-OH-VD3 levels in these same populations. By allowing additional UV-B penetration and intracutaneous VD3 formation, the latitude-dependent gradient in FLG mutations, likely together with other concurrent mutations in VD3 metabolic pathways, provide a non-pigment-based mechanism that sustains higher levels of circulating VD3 in northern Europeans. At the time that FLG mutations evolved, xerosis due to FLG deficiency was a lesser price to pay for enhanced VD3 production. Yet, the increase in FLG mutations has inadvertently contributed to an epidemic of atopic diseases that has emerged in recent decades.

Keywords

Filaggrin Human evolution Pigmentation Skin color Vitamin D3

Abbreviations

7DHC

7-Dehydrocholesterol

FLG

Filaggrin

KYA

Thousand years ago

t-UCA

Trans-urocanic acid

UV

Ultraviolet

VD3

Vitamin D3

Supplementary material

11692_2014_9282_MOESM1_ESM.doc (298 kb)
Supplementary material 1 (DOC 298 kb)

Copyright information

© Springer Science+Business Media New York 2014