The contribution of common regulatory and protein-coding TYR variants in the genetic architecture of albinism

Abstract

ABSTRACTGenetic diseases have been historically segregated into rare Mendelian and common complex conditions.1,2 Large-scale studies using genome sequencing are eroding this distinction and are gradually unmasking the underlying complexity of human traits.3–8 We studied a cohort of 1,313 individuals with albinism aiming to gain insights into the genetic architecture of rare, autosomal recessive disorders. We investigated the contribution of regulatory and protein-coding variants at the common and rare ends of the allele-frequency spectrum. We focused on TYR, the gene encoding tyrosinase, and found that a promoter variant, TYR c.-301C>T [rs4547091], modulates the penetrance of a prevalent, disease-associated missense change, TYR c.1205G>A [rs1126809]. We also found that homozygosity for a haplotype formed by three common, functional variants, TYR c.[-301C;575C>A;1205G>A], confers a high risk of albinism (OR>77) and is associated with reduced vision in UK Biobank participants. Finally, we report how the combined analysis of rare and common variants increases diagnostic yield and informs genetic counselling in families with albinism.