I-Heterozygous yigama elisetshenziselwa izakhi zofuzo ukuchaza uma ukuhlukahluka kwesigcawu (eyaziwa ngokuthi alleles) kubhanjiswa endaweni efanayo (locus) ku- chromosome . Ngokuphambene, u- homozygous uma kukhona amakhophi amabili e-allele efanayo endaweni efanayo.
Igama elithi heterozygous lisuselwa ku "hetero-" elisho okuhlukile futhi "okushoyo" okuhlobene neqanda elivundisiwe (zygote).
Ukunquma izici
Abantu babizwa ngokuthi izidakamizwa ze-diploid ngoba banama-alleles amabili endaweni ngayinye, ne-allele eyodwa ezuzwa ifa elivela kumzali ngamunye. Ukubambisana okuqondile kwe-alleles kuhumusha ekuguqukeni kwezimpawu zomuntu siqu.
I-allele ingaba yinto ephakeme noma ephindaphindiwe. Ama-alleles amakhulu kakhulu yiwo aveza isici ngisho noma kukhona ikhophi eyodwa kuphela. Ama-alleles avuselelayo angaveza kuphela uma kukhona amakhophi amabili.
Esinye isibonelo esinjalo ngamehlo aluhlaza (okuyinto ephezulu) namehlo aluhlaza okwesibhakabhaka (okuyinto ephindaphindiwe). Uma izintambo zikhona i-heterozygous, i-allele ephezulu izodalula phezu kwe-allele ephindaphindiwe, okubangelwa amehlo asundu. Ngesikhathi esifanayo, lo muntu wayezobhekwa njengomuntu "othwala" we-allele ephindaphindiwe, okusho ukuthi i-blue eye allele ingadluliselwa kwinzalo ngisho noma lowo muntu unamehlo aluhlaza.
Ama-alleles angase abe okungaqondakali ngokuphelele, ifomu eliphakathi lefa lapho kungekho khona i-allele ekhonjiswa ngokuphelele kunomunye.
Isibonelo salokhu singase sibandakanye i-allele ehambisana nesikhumba esimnyama (lapho umuntu enesifo esinengi se-melanin ) ehambisana ne-allele ehambisana nesikhumba esikhanyayo (lapho kune-melanin encane) ukudala ithoni yesikhumba endaweni ethile phakathi.
Ukuthuthukiswa kwezifo
Ngaphandle kwezici zomzimba zomuntu ngamunye, ukubambisana kwama-heterozygous alleles ngezinye izikhathi kungashintsha engozini ephakeme yezimo ezithile ezifana nokukhubazeka kokuzalwa noma izifo zokuzimela (izifo ezizuzwa nge-genetics).
Uma i-allele ishukunyiswa (okusho ukuthi ayiphutha), isifo singadluliselwa enzalweni ngisho noma umzali engaboni izibonakaliso zesifo. Ngokuphathelene ne-heterozygosity, lokhu kungathatha enye yefomu:
- Uma izinsolo ziyi-heterozygous ngokweqile, i-allele engafanele ingaba yinto ephindaphindiwe futhi ingabonakali. Esikhundleni salokho, lowo muntu uzoba othwala.
- Uma izintambo ziyi-heterozygous eyinhloko, i-allele engafanele ingabusa. Esimweni esinjalo, lo muntu angathinteka noma angathinteki (uma kuqhathaniswa nokubusa okungenayo i-homozygous lapho umuntu angathinteka khona).
Amanye ama-pairings we-heterozygous ayengamane abeke umuntu esimweni sempilo esifana nesifo se-celiac nezinhlobo ezithile zomdlavuza . Lokhu akusho ukuthi umuntu uzothola lesi sifo; umane nje ukhombisa ukuthi umuntu usemngciphekweni omkhulu. Ezinye izici, ezifana nendlela yokuphila nemvelo, nazo zizodlala indima.
Ukuphazamiseka kwe-Gene Single
Ukuphazamiseka kwezakhi zofuzo yilabo abangelwa i-allele eyodwa eguquliwe kunokuba ababili. Uma ngabe i-allele eguquguqukayo iguquguquka, ngokuvamile umuntu ngeke ahlaselwe. Kodwa-ke, uma i-allele eguquguqukayo inamandla, ikhophi eguquliwe ingadlula ikhophi ephindaphindiwe futhi ibangele izinhlobo ezincane kakhulu zesifo noma isifo esibonisa ngokugcwele.
Ukuphazamiseka kwezakhi zofuzo ezingajwayelekile kungavamile. Phakathi kwezinye zezifo ezivame kakhulu eziphathelene ne-heterozygous:
- Isifo sikaHuntington yisifo esizuzwa njengefa esiholela ekufeni kwezingqamuzana zobuchopho. Lesi sifo sibangelwa ukuguqulwa okuphawulekayo kunoma iyiphi eyodwa noma kokubili kokubili kwegesi okuthiwa i- Huntingtin .
- I-neurofibromatosis uhlobo-1 yinkinga ezuzwe njengefa lapho izikhumba ze-nerve zikhula khona esikhumbeni, emthonjeni, emasosheni, amehlo, kanye nobuchopho. Kudingeka ushintsho olulodwa kuphela olubalulekile ukuqala lo mphumela.
- I-hypercholesterolemia ejwayelekile (FH) yi-disorder ezuzwe njengezifo eziphezulu ze-cholesterol, ikakhulukazi "ezimbi" ze-lipoproteins (LDLs) eziphansi. Yiyona evame kakhulu kulezi zinkinga, ezithinta cishe abantu abangu-500.
Umuntu one-gene disorder disorder unethuba elingama-50/50 lokudlulisa i-allele eguquguqukayo kwengane ezoba yithwala.
Uma bobabili abazali bane-heterozygous mutation eguquguqukayo, izingane zabo ziyoba nethuba elilodwa-ezine lokuthuthukisa lesi sifo. Ingozi izoba efanayo kuwo wonke ukuzalwa.
Uma bobabili abazali banomthelela omkhulu wokuguqulwa kwe-heterozygous, izingane zabo zinamathuba angu-50 okuthola i-allele ephezulu (izimpawu ezingenalutho noma eziphelele), amaphesenti angama-25 amathuba okuthola zonke izinselele eziphezulu (ama-symptom), kanti amaphesenti angu-25 athola kokubili ama-alleles amaningi (azikho izimpawu).
I-Heterozygosity yenkimbinkimbi
I-heterozygosity eyakhiwe yi-state lapho kukhona khona izinhlangothi ezimbili ezihlukene eziqhamukayo ezindaweni ezifanayo, ezihlangene, ezingabangela izifo. Lezi, futhi, izifo ezingavamile ezivame ukuhlanganiswa nohlanga noma ubuhlanga. Phakathi kwazo:
- Isifo se-Tay-Sachs yisifo esingavamile, esizuzwe njengefa esenza ukuba kutholakale amangqamuzana egeyimu ebuchosheni nasemthonjeni womgogodla. I-disorder eguquguqukayo kakhulu engabangela izifo ngesikhathi sokusana, ukukhula noma ukukhula komuntu omdala. Ngenkathi i-Tay-Sachs ibangelwa ukuguqulwa kwezakhi zofuzo ze- HEXA , i-pairing ethize ye-alleles ekugcineni inquma ukuthi iyiphi isifo esithathayo. Ezinye izinhlanganisela zihumusha ezifweni zobuntwana; abanye bahumusha ekufikeni kwesifo kamuva.
- I-Phenylketonuria (i-PKU) isifo sofuzo ngokuyinhloko esithinta izingane lapho into ebizwa ngokuthi i-phenylalanine iqoqa ebuchosheni, ibangela ukugabha, ukuphazamiseka kwengqondo nokukhubazeka kwengqondo. Kukhona ukuhlukahluka okukhulu kwezakhi zofuzo ezithinta i-PKU, i-pairings engabangela izinhlobo ezimbi futhi ezimbi kakhulu zesifo.
Ezinye izifo lapho i-heterozygote engakhiwa nayo ingadlala khona yi-cystic fibrosis, i-sickle cell anemia, ne-hemochromatosis (insimbi eqinile egazini).
I-Heterozygote Advantage
Nakuba ikhophi eyodwa ye-allele isifo ngokuvamile ayibangeli ukugula, kunamacala lapho ingahlinzeka khona ukuvikeleka kwezinye izifo. Lokhu kuyinto ebizwa ngokuthi i-heterozygote inzuzo.
Kwezinye izimo, i-allele eyodwa ingashintsha umsebenzi womzimba womuntu ngendlela yokumenza lowo muntu aphikisana nezifo ezithile. Phakathi kwezibonelo:
- I-sickle cell anemia yisifo esiyinkinga yezofuzo esibangelwa izinselele ezimbili eziphindaphindiwe. Ukuba ne-alleles zombili kubangele ukulimazeka nokuzibulala okusheshayo kwamangqamuzana egazi obomvu. Ukuba ne-allele eyodwa kuphela kungabangela isimo esibi kakhulu okuthiwa i-sickle cell trait lapho amaseli ambalwa kuphela angasebenzi kahle. Lezi zinguquko ezinzima zanele ukuvikela ukuvikela imilariya ngokuvikela ama-blood cells anesifo esisheshayo kunokuba i-parasite ikhule.
- I-Cystic fibrosis (CF) isifo esiyinkimbinkimbi sezakhi zofuzo esingabangela ukukhubazeka okunzima kwamaphaphu kanye nomgudu wokugaya. Kubantu abane-homolegous alleles, i-CF ibangele ukwakhiwa okunamandla, okunamathelayo emaphashini nasemaphethweni emathunjini. Kubantu abane-alletero heterozygous, umphumela ofanayo, naphezu kokunciphisa, kunganciphisa ukuhlukunyezwa komuntu ekilera nasomkhuhlane we-typhoid . Ngokukhiqiza umkhiqizo we-mucus, umuntu ungaphansi kokubona umphumela wokulimaza osulelekile.
Umphumela ofanayo ungase uchaze ukuthi kungani abantu abane-heterozygous alleles yezifo ezithile zokuzibulala ezibonakala sengathi banomngciphezi ophansi wezibonakaliso ze- hepatitis C kamuva.
> Imithombo:
> Al-Chalabi, A. kanye no-Almasy, L. (2009) I- Genetics of Complex Human Illness: Umqulu Wezincwadi (I-1st Lab Lab). ENew York, eNew York: I-Cold Spring Harbor Laboratory Press. I-ISBN-13: 978-0879698836.
> I-Genetic Alliance. (2010) Ukuqonda amaGenesis: Isiqondiso seSifunda saseColombia kubantu abagulayo kanye nabasebenzi bezempilo. "Isithasiselo G: Ukuphazamiseka Okungavamile Kwe-Gene . " IWashington, DC: UMnyango WezeMpilo wase-Columbia. I-PMID: 23586106.
> Wynbrandt, J. noLudman, M. (2008) I-Encyclopedia of Genetic Disorders ne-Birth Defects (U-3rd Edition). I-New York, eNew York: iLabhulali yeMpilo nokuPhila. I-ISBN-13: 978-0816063963.