I-Heterozygous ibinzana elisetyenziswe kwimfuza ukuchaza xa iinguqu ezimbini ze-gene (ezaziwa njenge alleles) zidibene kwindawo enye (indawo) kwi- chromosome . Ngokwahlukileyo, i- homozygous xa kukho iikopi ezimbini zendawo efanayo kwendawo efanayo.
Igama elithi heterozygous lisuka kwi-"hetero-" lithetha intsingiselo kwaye "-engqondo" ehambelana neqanda elichumayo (zygote).
Ukuqulunqwa kweeMpawu
Abantu babizwa ngokuba yi-diploid eziphilayo ngenxa yokuba bane-alleles ezimbini kwi-locus ngayinye, kunye ne-allele enye eyayizuza ilifa kumzali ngamnye. Ikhonkco elithile le-alleles liguqulela ukuhluka kwiimpawu zobomi bomntu.
I-allele ingaba yinto ephezulu okanye ephindaphindiweyo. Ii-alleles eziphezulu zizo zibonisa umxholo nokuba kukho ikhophi enye kuphela. Ama-alleles asetyenziswayo angabonisa kuphela ukuba kukho iikopi ezimbini.
Omnye umzekelo unamehlo aluhlaza (okubaluleke kakhulu) kunye namehlo aluhlaza (okugqithisileyo). Ukuba i-alleles i-heterozygous, i-allele ephezulu iyazibonakalisa ngokugqithiseleyo, okubangele amehlo ahlaza. Ngelo xesha, umntu uya kuthathwa ngokuba "umphathiswa" we-allele, ebonisa ukuba i-blue eye allele inokudluliselwa kwinzala nangona loo mntu unamehlo aluhlaza.
Izibhengezo zinokuthi zingabikho ngokungaqhelekanga, uhlobo oluphakathi lwelifa apho kungabikho khona i-allele ebonakaliswe ngokupheleleyo ngaphaya komnye.
Umzekelo wale nto ungabandakanya i-allele ehambelana nolusu olumnyama (apho umntu unelinye i-melanin ngaphezulu) edibene ne-allele ehambelana nolusu olukhanyayo (apho kukho i-melanin encinane) ukudala ithoni yesikhumba kwindawo ethile phakathi.
Uphuhliso lwezifo
Ngaphandle kweempawu zobuntu, i-pairing ye-heterozygous alleles ngamanye amaxesha inokuguqulela kumngcipheko ophezulu weemeko ezithile ezifana neziphene zokuzalwa okanye iziphazamiso ze-autosomal (izifo ezizuzwe kwi-genetics).
Ukuba i-allele iguqulwa (ithetha ukuba iphosakeleyo), isifo sinokudluliselwa kwintwana nokuba ngaba umzali akanakufumana iimpawu zesifo. Ngokumalunga ne-heterozygosity, oku kunokuthatha enye yeendlela ezahlukeneyo:
- Ukuba i-alleles i-heterozygous ngokweqile, i-allele ephosakeleyo iya kuba yinto engapheliyo kwaye ingabonakali. Endaweni yoko, umntu uya kuba ngumphathiswa.
- Ukuba i-alleles i-heterozygous ephezulu, i-allele ephosakeleyo iya kuba yinto ephezulu. Kwimeko enjalo, loo mntu unako okanye angathintekiyo (xa kuthelekiswa nokulawulwa kwamanye amazwe apho umntu uya kuthinteka khona).
Ezinye i-heterozygous pairings ziza kubangela ukuba umntu abe nempilo kwiimeko zempilo ezifana nesifo se-celiac kunye neentlobo ezithile zomhlaza . Oku akuthethi ukuba umntu uya kufumana isifo; libonisa nje ukuba umntu usemngciphekweni ophezulu. Ezinye izinto, ezinjengendlela yokuphila nokusingqongileyo, ziya kudlala indima.
Iingxaki zeGenesis
Iingxaki zemizimba engabodwa yilezo ezibangelwa ngumntu omnye oshukunyiswayo ngaphandle kwembini. Ukuba i-allele eguquguqukayo iyinto engapheliyo, loo mntu akayi kuhluthwa. Nangona kunjalo, ukuba i-allele eguquguqukayo iphezulu, ikopi eguquguqukayo ingaphaya iikopi ephindaphindiweyo kwaye ibangele iifom ezincinci zesifo okanye izifo ezibonakalisa ngokupheleleyo.
Iingxaki zomzimba ezingaqhelekanga azifaneki. Phakathi kwezinye zeengxaki eziqhelekileyo ze-heterozygous:
- Isifo sikaHuntington sisifo esizuze njengefa esiphumela ekufeni kweeseli zobuchopho. Esi sifo kubangelwa utshintsho oluphambili kwi-one okanye zombini i-alleles yomgulo ogama linguHuntingtin .
- Uhlobo lwe-Neurofibromatosis uhlobo-1 luyintlupheko ezuze ilifa apho izikhumba ze-nerve zikhula kwilinqe, umlenze, amathambo, amehlo kunye nengqondo. Kuphela kuguquka oluphambili olufunekayo ukuze kuqaliswe le mpembelelo.
- I-hypercholesterolemia eqhelekileyo (FH) yintlupheko ezuzwe njenge-cholesterol ephezulu, ngokukodwa "i-bad" ye-lipoproteins (i-LDLs). Kuyeyona ndlela ixhaphake kakhulu kulezi ngxaki, ezichaphazela abantu abayi-500.
Umntu onesifo sengxaki esisodwa somzimba unekhefu lama-50/50 lokudlulisa ukuguquka komntwana oza kuba ngumthuthi.
Ukuba ngaba bobabini abazali banokuguqulwa kwe-heterozygous mutation, abantwana babo baya kuba nelinye ithuba elilodwa lokuhlakulela ingxaki. Umngcipheko uya kufana nawo onke azalwa.
Ukuba ngaba bobabini abazali banengxaki yokuguqula i-heterozygous, abantwana babo baneempesenti ezingama-50 zokufumana i-allele ephezulu (iimpawu ezikhethekileyo okanye ezipheleleyo), ama-25 ekhulwini amathuba okufumana i-alleles (iimpawu) eziphambili, kunye neepesenti ezingama-25 zokufumana i-alleles (akukho mpawu).
Heterozygosity
I-heterozygosity yamaqumrhu yindawo apho kukho izibini ezihlukeneyo ezahlukeneyo kwiindawo ezifanayo, kunye kunye, ezinokubangela izifo. Ezi, kwakhona, ukuphazamiseka okungaqhelekanga ezidla ngokuxhomekeke kubuhlanga okanye ngokobuhlanga. Phakathi kwabo:
- Isifo se-Tay-Sachs sisifo esingaqhelekanga, esizuze ilifa elibangela ukutshatyalaliswa kweeseli zesisongela engqondweni nasemgodleni. Ingxaki eguquguqukayo kakhulu engabangela izifo ebusana, ebusheni okanye emva komdala. Ngethuba i-Tay-Sachs ibangelwa ukuguqulwa kwemfuyo ye- HEXA gene, yindlela yokudibanisa i-alleles ekugqibeleni inquma ukuba yintoni isifo esithathayo. Ezinye izidibaniso ziguqulela kwisifo somntwana; abanye baguqulela ekugqibeleni izifo ziza kuqala.
- I-Phenylketonuria (PKU) yintlupheko yezofuzo ezichaphazela abantwana apho into ebizwa ngokuba yi-phenylalanine iqokelela kwingqondo, ibangele ukuphazamiseka, ukuphazamiseka kwengqondo kunye nokukhubazeka kwengqondo. Kukho iintlobo ezahlukeneyo zokuguquka kwemvelo ezihambelana ne-PKU, ezo zibini ezingakhokelela kwiifom ezinamandla kunye nezibi kakhulu zesifo.
Ezinye izifo apho i-heterozygotes eneengqungquthela inokudlala indima ye-cystic fibrosis, i-sickle cell anemia, kunye ne-hemochromatosis (insimbi engaphezulu kwigazi).
Heterozygote Inzuzo
Ngoxa ikopi enye yesifo esele isingabangela ukugula, kukho iimeko apho kunokukhusela ezinye izifo. Le yinto ebizwa ngokuba yi-heterozygote inzuzo.
Kwezinye iimeko, enye i-allele ingakwazi ukuguqula umsebenzi womzimba ngendlela efana nokwenza loo mntu unqandeke kwizifo ezithile. Phakathi kwemizekelo:
- Isifo se-anemia yesifo ngumzimba wesifo somfuzo obangelwa zi-two alleles. Ukuba nazo zonke iintolo zenza i-malformation kunye nokutshabalalisa ngokukhawuleza kweeseli ezibomvu zegazi. Ukuba ne-allele eyodwa kuphela kunokubangela imeko engaphantsi kakhulu ebizwa ngokuba ngumzila we-sickle cell apho iiseli ezithile kuphela ezingalunganga. Ezi zinguqu ezinzulu zaneleyo ukubonelela ngokukhuseleka kwemvelo ngokumalunga ne- malariya ngokubulala amaseli egazini egazini ngokukhawuleza kunokuba i-parasite ivelise.
- I-Cystic fibrosis (CF) yintlupheko yesifo se-genetic engabangela ukuphazamiseka okukhulu kwemiphunga kunye nomgudu wokutya. Kubantu abane-homozygous alleles, i-CF ibangele i-mucus ekhusiweyo, enamathele emiphakeni kunye neendlela zesisu. Kubantu abane-heterozygous alleles, impembelelo efanayo, nokuba iyancitshiswa, inokunciphisa ubungozi bomntu kwi- k'holera kunye ne- typhoid fever . Ngokunyuka komkhiqizo we-mucus, umntu uncinci ngenxa yempembelelo yokurhuda.
Isiphumo esifanayo sinokucacisa ukuba kutheni abantu abane-heterozygous alleles ezithile zeengxaki ezizimeleyo ezibonakalayo banomngcipheko omncinci weempawu ze- hepatitis C ezizayo.
> Imithombo:
> Al-Chalabi, A. kunye no-Almasy, L. (2009) I- Genetics ye-Complex Izifo zabantu: I-Manual Manual (i-1st Lab Lab). ENew York, eNew York: I-Cold Spring Harbour yeLebhu yeeLebhu. I-ISBN-13: 978-0879698836.
> Genetic Alliance. (2010) Ukuqonda i- Genetics: Isikhokelo seSithili sase-Columbia kubaPhezulu kunye nabaPhezulu bezeMpilo. "IsiHlomelo G: Iingxaki ze-Gene ezingaxhatshazwayo . " IWashington, DC: ISithili seSebe lezeMpilo laseColumbia. PMID: 23586106.
> Wynbrandt, J. kunye noLudman, M. (2008) I-Encyclopedia ye-Genetic Disorders kunye ne-Defects Birth (3rd Edition). ENew York, eNew York: iThala leMpilo kunye noPhila. I-ISBN-13: 978-0816063963.