Of white tigers and solute carriers

Abstract

with OCA4 (The Human Gene MutationDatabase, HGMD 2013.1). However, thisGlycine 518 residue appears to be con-served through all available vertebrategenomes investigated, hence suggestinga relevant functional role at this position,plus it is true that other glycine-to-argi-nine amino acid changes in the SLC45A2protein have been already associatedwith OCA4 (data from HGMD 2013.1:p.G44R; p.G89R; p.G110R; p.G349R;p.G370R; p.G404R). Some indirect evi-dence of an altered association of themutant protein with membranes wasalso reported by the authors. However, itis probably expected, for a protein with12 transmembrane domains, that itwould remain associated with mem-branes, even in the presence of somedisruptive mutations, although theseminor topological alterations might actu-ally result in a loss-of-function pheno-type. The ultimate proof should beprovided by engineering this mutation inan experimental animal model (i.e.mouse or zebrafish) and/or, simply, byreporting its presence in human subjectsdiagnosed as OCA4.Finally, the authors investigated thelandscape where this SLC45A2 muta-tion was found in Snowflake’s genomeand showed that it is nicely locatedwithin a large run (40 Mbps) of homo-zygosity, orthologous to human chro-mosome 5 (where the humanSLC45A2 gene is located), indicatingthis allele was inside a block identicalby descent, characteristic for Mende-lian recessive disorders. Furthermore,by investigating the patterns of hetero-zygosity in the Snowflake’s genome,the authors inferred that it was likely aresult of inbreeding. Through computa-tional simulations they concluded thatthe most probable scenarios for Snow-flake’s parents were uncle/niece oraunt/nephew.It is always rewarding to put an endto previously unexplained observations,especially if these refer to remarkableindividuals such this unique albino gor-illa. Therefore, the authors of thisstudy must be praised for having com-pleted the quest for the genetic causeof the albinism of Snowflake. Person-ally, as someone born in Barcelonajust 1 yr before Snowflake and some-one that had the chance to witnesshis life through my visits at the Zoo,as many other visitors worldwide, it isalso good that the conservation plightof Snowflake’s relatives has beenhighlighted; let us hope that this is intime to contribute to the efforts toconserve these remarkable but endan-gered primates.