Ama-Chromosomes, izinhlobo ze-Trisomy, i-Heredity, ne-Down Syndrome
I-Down syndrome ibangelwa inombolo ye-chromosome eyengeziwe, kodwa lokhu kusho ukuthini ngempela? Yini ebangela i-chromosome eyengeziwe? Ingabe i-Down syndrome ingaba nefa? Ukuze uqonde ukuthi yini ebangela i-Down syndrome, udinga ukuqonda ngokugcwele ukuthi yiziphi i-chromosomes, nokuthi benzani. Ukuqonda i-genetics ye-Down syndrome kuyinselele, kodwa ukuthatha isikhathi sokugaya lolu lwazi kungabakhuthaza kubo bobabili abazali-ukuthi babe nabakhathazayo ngesikhathi sokukhulelwa, nabazali abanezingane ezine-Down syndrome abazibuza lo mbuzo onzima: "Kungani?"
Ukuqonda i-Genetics
Amaphakheji we-Genetic Information
Indlela elula yokucabanga ngama- chromosomes njengamaphakheji welwazi lofuzo. Umzimba womuntu wakhiwe yizo zonke izinhlobo zamaseli futhi ngaphakathi kwalawo maseli, ku-nucleus, yizakhi zethu zofuzo. AmaGenesis yiwona amayunithi wefa adluliselwa kusuka kwesinye isizukulwane kuya kwesinye. Zitholakala kuwo wonke amangqamuzana emizimbeni yethu futhi zinikeza imiyalelo yazo zonke izakhiwo nomsebenzi womzimba wethu. Abantu banezakhi zofuzo ezingaba ngu-25 000. Esikhundleni sokuba wonke ama-25,000 ahlasele ngaphakathi kwamaseli ngabanye, izakhi zethu zofuzo zikhona noma zifakiwe emakhromosomes kufana namaparele entanyeni.
Izitshalo
Izidalwa zakhiwe nge-DNA okuyinto i-molecule eyenziwe ngamakhemikhali amane ahlukene abizwa ngokuthi ama-bases, okuvame ukubhekwa yiziqalo zawo-A for adenine, T for thymine, G for guanine no C for cytosine. Lezi zisekelo ezingu-4 zakha "ikhodi yezofuzo" -uhlobo lwezinhlamvu zefa.
Izidalwa zakhiwe ngezingxenye ezincane ze-DNA kanti lezi zakhi zofuzo zikhona kuma-chromosomes. Uma ucabanga ngezisekelo njengezinhlamvu zamagama, izakhi zofuzo zingacatshangwa njengemisho. Umusho ngamunye (noma ifulethi) inikeza imfundo ethile yemithwalo yethu. Iqembu elilodwa lezakhi zofuzo lingase litshele ukuthi umbala wethu uyoba yimuphi umbala lapho enye inhlanganisela yezakhi zofuzo ingase isitshele indlela encane yethu encane okufanele ibe ngayo!
Lapho ososayensi befuna ukubhekisela kuzo zonke izakhi zethu zofuzo ndawonye, bakubiza ngokuthi "i-genome."
Ama-Chromosomes
I-Chromosomes, kanye nezakhi zofuzo ezibekwe kuzo, zingene ngezibili. Abantu banama-chromosomes angu-46 ahlelwe ngamabili angu-23. Ama-22 womabili we-chromosomes abizwa ngokuthi "ama- autosomes " futhi abalwa kusukela ku-1 kuya ku-22, kusukela kokukhulu kuya komncane kakhulu. Lezi zindima ezingu-23 zibizwa ngokuthi "ama- chromosomes ngokocansi " futhi ziqukethe i-X ne-Y emadodeni nama-chromosomes amabili e-females. I-Chromosomes ingabonwa ngaphansi kwe-microscope kepha izakhi zofuzo ezizimele ezikuzo azikwazi. Ukuhlolwa okuvumela ama-chromosomes ukuba abonwe (futhi abalwa) yi- test karyotype ,
I-Trisomy
Iningi labantu linama-chromosomes angu-46 noma ama-chromosomes angu-23. Abantu abane-Down syndrome bane-namba engaphezulu ye-chromosome engama-chromosomes angu-47. Lesi simo sibizwa nangokuthi "i- Trisomy 21. " I-Trisomy ivela egameni lesiLatini elithi "tri" elisho ukuthi ezintathu "ezinye" okusho umzimba futhi kubhekisela kuma-chromosomes. Abantu abane-trisomy 21 banemizimba emithathu engu-21, noma ama-chromosomes amathathu angama-21.
Ngenxa yokuthi ama-chromosomes yiziphakelalwazi zofuzo futhi aqukethe zonke izakhi zethu zofuzo noma iziyalezo, abantu abane-Down syndrome empeleni banekhophi amathathu yazo zonke izakhi zofuzo ezise-chromosome 21.
Kulinganiselwa ukuthi kunezinhlobo zomzimba ezingama-400 ku-chromosome 21. Ngakho-ke, abantu abane-Down syndrome baneziqondiso ezingaphezulu ezingu-400. Uma iziyalezo ezengeziwe zizwakala sengathi kufanele kube into enhle, empeleni kufana nokwengeza izithako ezengeziwe ku-iresiphi. Uyothola isidlo esifanayo esisisekelo (umzimba womuntu) kodwa ifomu nomsebenzi uhlukile.
Ngaphezu kwe-trisomy 21, kunezinye izinhlobo zesintu . I-Down syndrome, noma i-trisomy 21 yi-trisomy ejwayelekile kakhulu ye-autosomal, kodwa abantwana abane-trisomy 13 (i-Patau syndrome) ne-trisomy 18 (i-Edward's syndrome) ngezinye izikhathi bangase baqhubeke nokukhulelwa. Isikhathi sokuphila sezingane ezinamanye ama-trisomi aphansi kakhulu esihlobene ne-Down syndrome.
Ukukhulelwa nge-trisomy 15, 16, no-22 kuvame ukuqeda ukukhulelwa komzimba. Ama-trisomi kwamanye ama-chromosomes ayabonwa njalo futhi ngokuvamile aphela ekukhulelweni kokubeletha okuncane ngaphambi kokuba kuhlolwe ukuhlolwa.
Ama-chromosome e-sex chromosome ahlanganisa i-X ne-Y-chromosomes ajwayelekile, isibonelo, i- Klinefelter's syndrome (i-XXY) kulinganiselwa ukuthi ithinta 1 kubantu abangu-1000.
Ngokungafani ne-trismies, ezinye izinto ezingavamile ze-chromosome ezinganeni zibangelwa inani elinciphile lama-chromosomes, i- "monosomy." Isibonelo isifo se-Turner lapho i-chromosome eyodwa yobulili ilahlekile, i-X0 noma i-monosomy X.
Izimbangela ze-Trisomy
I-trisomy ye-chromosome ethize yimbangela yokuhlukunyezwa kumuntu noma iqanda ngaphambi kokukhulelwe. Ngokujwayelekile ama-chromsomes aphakama futhi ahlukaniswa ngendlela efanayo ngesikhathi sokuhlukaniswa. Ngama-chromosomes, kokubili ama-chromosomes aya eqanda elilodwa, ngakho-ke uma ehlangene ne-sperm (uma iqanda nesidoda lihlangana), kunezintathu.
Akukho lutho umuntu angayenza ukuvimbela i-trisomy, futhi akukho lutho umuntu angayenza ukuze enze i-trisomy. Kuyinto eyenzeka ngengozi eyenzeka ngaphambi kokukhulelwa (ngo-trisomy ephelele) kunoma iqanda noma i-sperm. Asazi ukuthi yini ebangela ukuba i-trisomy ivele, nakuba siyazi ezinye zezinto ezibeka ingozi ezandisa ingozi yalokhu okwenzekayo.
Izinhlobo ze-Trisomy 21
Kunezinhlobo ezintathu ezahlukene ze-trisomy 21:
Gcwalisa i-Trisomy 21 - I-trisomy egcwele 21 iphethwe ngamaphesenti angu-95 we-Down syndrome. Njengoba kuphawuliwe ngenhla, uma ama-chromosomes ehlela ukuhlukanisa (ukudala amaqanda noma i-sperm ngenqubo ebizwa ngokuthi i-meiosis), esikhundleni se-chromosome emibili ehlukanisa ukuya emaqanda ahlukene, kokubili ama-chromosomes aya eqanda elilodwa futhi awekho ama-chromosomes eya komunye. Lokhu kubizwa okungewona ukuhlanganiswa.
I-Translocation Trisomy 21 - I- trisomy Translocation 21 ivela cishe ezingamaphesenti amane ezane ne-Down syndrome. Esikhathini sokuthutha kukhona amakhophi amabili we-chromosome 21, kodwa izinto ezengeziwe ezivela ku-chromosome yesithathu yesithathu zinamathele (zithunyelwa kuye) enye i-chromosome. Lolu hlobo lwe-Down syndrome lungase luvele ngaphambi noma emva kokukhulelwa, futhi yilohlobo okungase ludluliselwe ngezinye izikhathi (njengefa.)
I-Mosaic Trisomy 21 - Okungavamile kakhulu kwe-Down syndrome, i-mosaic I-Down syndrome kwenzeka uma amanye amaseli anekhophi eyengeziwe ye-chromosome 21. Leli fomu le-trisomy livela ngemuva kokukhulelwa, kodwa aziwa ukuthi kungani kwenzeka. Nakuba abantu abane-trisomy ephelele 21 kanye ne-translocation 21 bafana, i-trisomy 21 ye-mosai ihlukahluka kuye ngokuthi inani lamaseli anomculo we-chromosome owengeziwe.
Ingabe I-Down Syndrome Ingaba Ifa?
Ngokuvamile, i-Down syndrome ayilona 'ifa' kodwa ingadluliselwa kubazali ukuya ezinganeni ezine-transmation trisomy 21 (okubalwa cishe ngamaphesenti amane abantu abane-Down syndrome.) Ku cishe ingxenye yesithathu yabantu abane-transmation trisomy 21, i-trisomy (ama-chromosome amabili ama-21 kanye nama-chromosome engeziwe angu-21 anamathele kwenye i-chromosome) izuze umzuzwana kumzali. Ingozi yomuntu onesi-trisomy-tranlocation 21 edlulisela isimo kumntwana cishe amaphesenti angu-10 kuya ku-15 kwabesifazane namaphesenti amathathu amadoda.
Njengoba ukudluliselwa kwe-trisomy 21 kuphela kubandakanya cishe amaphesenti amane abantu abane-Down syndrome, ngaphansi kwephesenti elilodwa lamacala angabhekwa njengefa.
Uma ingane noma umuntu omdala ene-Down syndrome ekhulelwa, ingozi ye-Down syndrome noma enye ukukhubazeka kwengqondo emntwaneni iphakathi kwamaphesenti angu-35 no-50. Njengoba abantu abaningi abanesifo se-Down syndrome bangabangela ukuphila okuphezulu kakhulu, futhi babone uthando nobuhlobo njengalabo abangenawo i-Down syndrome, lokhu kuyingozi ukuthi kudingeka kulinganiswe nezinzuzo zabazali-ukuba babe ngendlela ecabangelayo. Amaphesenti angaba ngu-50 abesifazane abane-Down syndrome bayakwazi ukukhulelwa.
Izingozi Zezingozi
Abazali abaningi abanezingane ezine-Down syndrome abanazo izici eziyingozi. Kubalulekile ukuqaphela ukuthi, kuze kube yimanje, azikho indlela yokuphila noma izimo ezingozini zemvelo ze-Down syndrome . Ngamanye amazwi, ngaphandle kokunyuka ngaminyaka yobudala (kanti namanje abesifazane abaningi abanezingane ezine-Down syndrome basha) akukho lutho olungasiza ukubikezela noma ukuvimbela ukuba nengane ene-Down syndrome.
Ingozi yomama kanye ne-Down Syndrome
Ngenkathi ama-trismium angenzeka kubantu banobudala obukhona, kukhona ubudlelwane obuphakathi kweminyaka yobudala kanye nethuba lokuba nomntwana one-trisomy. Inhlangano isho nje isayensi ye-link. Ukuhlangana akuyona imbangela. Leliphuzu elibalulekile, ngoba abantu bavame ukungaphansi kwekholo eliphutha lokuthi iminyaka yobudala idala i-Down syndrome. Lokhu akulona iqiniso. Asazi ukuthi yini ebangela ukuthi izidakamizwa zenzeke. Siyazi nje ukuthi njengoba abesifazane bekhula, ingozi yokukhulelwa nge-trisomy yanda.
Ngenkathi kunesixhumanisi phakathi kweminyaka yobudala kanye nokutholakala kwama-trismi, iningi lezingane ezine-Down syndrome zizalelwa omama abangaphansi kweminyaka engama-35. Lokhu kungenxa yokuthi kukhona abesifazane abasebancane kakhulu abanabantwana. Eqinisweni, izingane ezingamaphesenti angu-80 ezelwe nge-Down syndrome zizalwa abesifazane abangaphansi kuka-35 futhi isilinganiso sobudala bomama wengane ene-Down syndrome iminyaka engu-28. Ngokuvamile, amathuba okuthi owesifazane ongaphansi kweminyaka engama-30 abelethe ingane ene-Down syndrome ingaphansi kwe-1: 1000. Ingozi iyanda njengoba owesifazane ekhula, enezibalo ezingaba ngu-1: 112 eneminyaka engu-40 ubudala. Noma kunjalo, lokhu kusengaphansi kwephesenti eyodwa yabesifazane abakhulelwe abaneminyaka engama-40.
Ishadi lokuqhathanisa iminyaka yobudala kuya engozini ye-Down syndrome iyatholakala, kodwa kubalulekile ukuqapha abesifazane ngaphambi kokubuka leli shidi. Qinisekisa ukukhumbula ukuthi iningi labesifazane abakhulelwe abangaphezu kweminyaka engama-35 banabantwana abangenayo i-Down syndrome.
Abanye besifazane abaneminyaka engaphezu kwengu-35 (noma ezinye izici ezingozini) bangakhetha ukuba ne-amniocentesis ukuhlola isikrini se-Down syndrome noma ezinye izivivinyo zangaphambi kokubeletha. Isiqunto sokuthi noma lokhu kungabi nalokhu kuhlolwa singumuntu siqu, futhi kufanele kwenziwe ngosizo lokwazisa ngezakhi zofuzo. I-American College of Obstetrics ne-Gynecology incoma ukuthi bonke abesifazane banikezwe ukuhlolwa kokubeletha kwe-Down syndrome. Abanye besifazane bakhetha ukuthi lokhu kuhlolwa kwenziwe kokubili ukuqinisekiswa nokukwazi ukuhlela phambili, kuyilapho kunezizathu ezicacile zokuthi kungani abesifazane bekhetha ukungenzi izivivinyo zangaphambi kokubeletha.
Ingozi ye-Paternal Age ne-Down Syndrome
Kulinganiselwa ukuthi i-chromosome eyengeziwe e-Down syndrome ivela kumama iningi lesikhathi nangobaba (insimu) kuphela amaphesenti amane esikhathi. Ngenkathi ukukhula kweminyaka yobudala kuhlotshaniswa nenengozi ye-Down syndrome, okufanayo akulona iqiniso ekuthuthukiseni iminyaka yobudala ngenxa nje yokuthi amaqanda adala, kodwa isibindi senziwa ngaso sonke isikhathi kangangokuthi zivame amasonto ambalwa kuphela. Kodwa-ke, kukhona izimo zofuzo ngaphandle kwe-Down syndrome ezixhumene neminyaka yobudala obudala, njenge- achondroplasia (dwarfism) ne-Marfan syndrome.
Ucwaningo kanye nekusasa
Ngenkulumo mayelana ne-Human Genome Project kanye ne- gene therapy abazali baye babuza umbuzo omuhle kakhulu: "Kungani ukuphathwa kwegciwane kungasetshenziselwa ukulungisa isimo esingavamile ku-Down syndrome?" Ngeshwa, ukuqonda kwethu kwezakhi zofuzo akukhona okwamanje. Iphi i-therapy yokwelapha ingasiza kakhulu okungenani esikhathini esizayo esiseduze, isebenza nezifo ezingavamile zegenes. Isimo esibangelwa isakhi sofuzo esingaphezu kwesisodwa, kungabi yilapho i-chromosome yonke ingaba nzima ukuphatha nge-gene therapy. Ngakho-ke abacwaningi babheka ukuthi kungenzeka yini nge-epigenetic engineering-epigenetics insimu ebheka inkulumo (ukubonakaliswa kwemitholampilo) yezakhi zofuzo esikhundleni sezakhi zofuzo ngokwabo.
Lokho kusho ukuthi ukuphathwa kwezingane ezizalwa nge-Down syndrome kuye kwathuthuka kakhulu eminyakeni embalwa edlule.
Ngaphansi
Okubalulekile ukuthi siyazi ukuthi kunesixhumanisi noma ubudlelwano phakathi kweminyaka yobudala nengozi yokuba nomntwana one-trisomy efana ne-Down's syndrome, kodwa akekho owaziyo imbangela ethize yezinhlungu.
Imithombo:
UDeker, A., uDe Deyn, P., noM. Rots. I-Epigenetics: I-Neglected Key Yokunciphisa Ukunciphisa Ukufunda Nezinkumbulo ku-Down Syndrome. I-Neuroscience kanye nokubuyekezwa kwe-Biobehavioral . 2914. 45: 72-84.
I-Mentis, A., i-Epigenomic Engineering ye-Down Synrome. I-Neuroscience kanye nokubuyekezwa kwe-Biobehavioral . 2016. 71: 323-327.