Luyini ucwaningo lwe-genome-wide association study (GWAS)?
Ku-genomics, ucwaningo lwe-genome-wide association study (GWA study, noma i-GWAS), ucwaningo lokuhlola lwe-genome-wide set of genetic variants kubantu abahlukene ukubona ukuthi ngabe kukhona yini okuhlukile okuhambisana nesici. Izifundo ze-GWA ngokuvamile zigxila ekuxhumaneni phakathi kwama-single-nucleotide polymorphisms (SNPs) nezici ezinjengezifo zabantu ezinkulu, kodwa zingasetshenziswa ngokulinganayo kunoma yiziphi ezinye izinhlobo zofuzo nakwezinye izinto eziphilayo.  Lapho zisetshenziswa kubantu, izifundo ze-GWA ziqhathanisa i-DNA yabahlanganyeli abanama-phenotypes ahlukahlukene esici noma isifo esithile. Laba ababambiqhaza bangaba abantu abanesifo (amacala) kanye nabantu abafanayo abangenaso lesi sifo (ukulawulwa), noma bangaba abantu abanezinhlobo ezahlukene zezimpawu ezithile, ngokwesibonelo umfutho wegazi. Le ndlela yaziwa ngokuthi i-phenotype-first, lapho ababambiqhaza behlukaniswa khona kuqala ngokubonakaliswa kwabo kwemitholampilo, ngokungafani ne-genotype-first. Umuntu ngamunye unikeza isampula le-DNA, okuvela kuyo izigidi zezinhlobo zofuzo zifundwa kusetshenziswa ama-SNP array. Uma kunobufakazi obuphawulekayo bokuthi uhlobo olulodwa lwenguquko (i-allele eyodwa) luvame kakhulu kubantu abanesifo, kuthiwa inguquko ihlobene nesifo. Ama-SNP ahlobene nawo abe esebhekwa njengamamaki esifunda sezakhi zofuzo somuntu esingathonya ingozi yesifo.  Izifundo ze-GWA ziphenya i-genome yonke, ngokungafani nezindlela ezihlola ngokukhethekile inani elincane lezifunda zofuzo ezichazwe kusengaphambili. Ngakho-ke, i-GWAS iyindlela engahambisani nomuntu, ngokungafani nezifundo eziqondene nomuntu eziqondene nofuzo. Izifundo ze-GWA zikhomba ama-SNP nezinye izinhlobo ze-DNA ezihlobene nesifo, kodwa azikwazi ngokwazo ukucacisa ukuthi yiziphi izakhi zofuzo eziyimbangela.  I-GWAS yokuqala eyaphumelela eyanyatheliswa ngo-2002 yayihlolisise isifo sokuhlaselwa yisifo senhliziyo. Le ndlela yokuhlola yabe isisetshenziswa esifundweni esiyingqophamlando se-GWA sika-2005 esasihlola iziguli ezinokukhubazeka kwe-macular okuhlobene nobudala, futhi sathola ama-SNP amabili anokuhluka okuphawulekayo kwe-allele frequency uma kuqhathaniswa nezilawuli ezinempilo. Kusukela ngo-2017, izifundo ezingaphezu kuka-3 000 ze-GWA zabantu zihlolisise izifo nezici ezingaphezu kuka-1 800, futhi kutholakale izinkulungwane zezinhlangano ze-SNP. Ngaphandle kwezimo zezifo zofuzo ezingavamile, lezi zinhlangano zibuthakathaka kakhulu, kodwa nakuba zingase zingachazi ingozi enkulu, zinikeza ukuqonda ngezakhi zofuzo nezindlela ezingaba ezibalulekile.