Chromosomes, Trisomy Types, Heredity, ndi Down Syndrome
Matenda a m'munsi amayamba ndi nambala yambiri ya chromosome, koma kodi izi zikutanthauza chiyani? Kodi zimayambitsa chromosome yowonjezera? Kodi matenda a Down can be inherited? Kuti mumvetsetse chomwe chimayambitsa matenda a Down syndrome, muyenera kumvetsa bwino zomwe ma chromosomes ali, ndi zomwe akuchita. Kumvetsetsa chibadwa cha matenda a Down syndrome n'kovuta, komabe kupatula nthawi yokumba mfundozi kungalimbikitse makolo onse awiri omwe ali ndi nkhawa pa nthawi yomwe ali ndi pakati, komanso makolo omwe ali ndi mwana ndi Down syndrome omwe akudzifunsa okha funso lovuta: "Chifukwa chiyani?"
Kumvetsa Genetics
Maphukusi a Zosintha Zachibadwa
Njira yosavuta yoganizira za chromosomes ndi monga phukusi la chidziwitso cha majini. Thupi la munthu limapangidwa ndi mitundu yosiyanasiyana ya maselo ndipo mkati mwa maselo awa, mu mtima, ndi majini athu. Matenda ndi magulu a cholowa omwe amachokera ku mibadwomibadwo. Iwo ali mu selo lirilonse la matupi athu ndipo amapereka malangizo kwa dongosolo lililonse ndi ntchito ya thupi lathu. Anthu ali ndi majini pafupifupi 25,000 osiyanasiyana. M'malo mokhala nawo 25,000 akuzungulira mkati mwa maselo pawokha, majini athu alipo kapena amapangidwa pa ma chromosomu m'malo mofanana ndi ngale pa mkanda.
Chibadwa
Zamoyo zimapangidwa ndi DNA yomwe ili ndi molekyu yokhala ndi mankhwala anayi omwe amatchedwa mabowo, omwe amatchulidwa ndi oyambirira awo-A a adenine, T a thymine, G a guanine ndi C a cytosine. Maziko awa 4 amapanga "ma chibadwa" - mtundu wa alfabeti.
Zamoyo zimapangidwa ndi tizigawo ting'onoting'ono ta DNA ndipo majini ameneŵa ali pa chromosome. Ngati mukuganiza zazomwe zili ngati zilembo, ndiye kuti majini angaganizidwe ngati ziganizo. Chiganizo chirichonse (kapena jini) chimapereka malangizo enieni a matupi athu. Ma jini awiri anganene kuti maso athu adzakhala otani pamene magulu ena amatha kunena momwe kamwana kathu kakang'ono kamakhalira!
Pamene asayansi akufuna kutchula ma jini athu onse pamodzi, amatcha "genome."
Chromosomes
Chromosomes, komanso majini omwe ali pa iwo, bwerani pawiri. Anthu ali ndi ma chromosome 46 okonzedwa kukhala awiri awiri. Mawiri awiri oyambirira a ma chromosomes amatchedwa " autosome " ndipo ali owerengeka 1 mpaka 22, kuyambira kukula mpaka wamng'ono. Gulu lachiwirili limatchedwa " chromosomes " ndipo limakhala ndi X ndi Y mu amuna ndi ma X chromosomes azimayi. Chromosomes imatha kuwona pansi pa microscope koma majini omwe ali pa iwo sangathe. Chiyeso chomwe chimalola ma chromosomes kuti awonedwe (ndi kuwerengedwa) ndi mayeso a karyotype ,
Trisomy
Anthu ambiri ali ndi ma chromosomes 46 kapena awiri awiri a chromosomes. Anthu omwe ali ndi matenda a Down syndrome ali ndi chromosome yowonjezera 21 yowonjezera ma 47 chromosomes. Matendawa amatchedwanso " Trisomy 21. " Trisomy imachokera ku liwu lachilatini "tri" lomwe limatanthawuza atatu ndi "ena" omwe amatanthawuza thupi ndikutanthauza ma chromosome. Anthu omwe ali ndi trisomy 21 ali ndi matupi atatu, kapena ma chromosome atatu.
Chifukwa ma chromosome ndiwo mauthenga a majini ndipo ali ndi majini athu onse kapena malangizo, anthu omwe ali ndi Down syndrome ali ndi makope atatu a majini omwe ali pa chromosome 21.
Zikuoneka kuti pali majini 400 pa chromosome 21. Choncho, makamaka anthu omwe ali ndi Down syndrome ali ndi malangizo owonjezera 400. Ngakhale kukhala ndi malangizo owonjezera kumveka ngati ziyenera kukhala chinthu chabwino, zimakhala ngati kuwonjezerapo zowonjezera zowonjezera. Mudzapeza chakudya chofanana (thupi laumunthu) koma mawonekedwe ndi ntchito ndi zosiyana.
Kuphatikiza pa trisomy 21, palinso zinthu zina zaumunthu . Matenda otchedwa Down syndrome, kapena trisomy 21 ndi otchuka kwambiri autosomal trisomy, koma ana omwe ali ndi trisomy 13 (Patau syndrome) ndi trisomy 18 (Edward's syndrome) nthawi zina amatha kukhala ndi pakati. Chiyembekezo cha moyo kwa ana omwe ali ndi mavuto enawa ndi otsika poyerekeza ndi Down syndrome.
Mimba yomwe ili ndi trisomy 15, 16, ndi 22 imatha kumapita padera. Matenda a ma chromosome ena sawoneka kawirikawiri ndipo nthawi zambiri amatha kutaya mimba nthawi yayitali asanayambe kuwunika.
Kugonana kwa chromosome zokhudzana ndi ma chromosome a X ndi Y zimakhala zachilendo, mwachitsanzo, Klinefelter's syndrome (XXY) akuti akukhudza 1 mwa amuna 1000.
Mosiyana ndi zovuta, matenda ena a chromosome m'mimba mwachisawawa amayamba chifukwa cha kuchepa kwa ma chromosomes, 'monosomy'. Chitsanzo ndi matenda a Turner omwe chromosome imodzi yogonana ikusowa, 45 X0 kapena X osasunthika X.
Zifukwa za Trisomy
Trisomy ya chromosome yeniyeni ndi zotsatira za kusokonezeka mu umuna kapena dzira asanatenge mimba. Kawirikawiri ma chromsomes amamangirira mmwamba ndipo amasiyanitsidwa mofanana panthawi yopatukana. Ndi zowopsa, ma chromosome amapita ku dzira limodzi, kuposa pamene ali ndi umuna (pamene dzira ndi umuna zimagwirizanitsa), pali zitatu.
Palibe chilichonse chimene aliyense angachite kuti ateteze trisomy, ndipo palibe chimene wina angachite kuti atenge trisomy. Ndizochitika mwangozi zomwe zimachitika asanabadwe (mu trisomy wathunthu) mu dzira kapena umuna. Sitikudziwa chomwe chimayambitsa trisomy, ngakhale tikudziwa zoopsa zina zomwe zimapangitsa chiopsezo cha izi.
Mitundu ya Trisomy 21
Pali mitundu itatu ya trisomy 21:
Trisomy Complete 21 - Trisomy Complete 21 imayang'anira pafupifupi 95 peresenti ya Down syndrome. Monga tanenera pamwambapa, ma chromosome amayamba kugawikana (kupanga mazira kapena umuna mu njira yotchedwa meiosis), mmalo mwa chromosome iwiri yosiyana kupita mazira osiyana, ma chromosome amapita ku dzira limodzi ndipo palibe ma chromosomes amapita ku winayo. Izi zimatchedwa non-disjunction.
Translocation Trisomy 21 - Translocation trisomy 21 imachitika pafupifupi pafupifupi anayi a ana omwe ali ndi Down syndrome. Mu translocation muli makope awiri a chromosome 21, koma zina zochokera ku chromosome yachiwiri ya 21 imamangirizidwa (kutumizidwa ku) wina chromosome. Mtundu wotere wa Down syndrome ukhoza kukhalapo kapena asanakhale ndi pakati, ndipo ndi mawonekedwe omwe nthawi zina angadutse (anabadwa).
Mosaic Trisomy 21 - Zomwe si zachilendo za matenda a Down syndrome, matenda otsika a pansi amapezeka pamene maselo ena ali ndi kachilombo kake ka chromosome 21. Mtundu uwu wa trisomy umachitika pambuyo pathupi, koma sizidziwika chifukwa chake zimachitika. Ngakhale kuti anthu okhala ndi trisomy 21 ndi mawotchi 21 ali ofanana, trisomy 21 yamalasi amasiyana malinga ndi chiwerengero cha maselo omwe ali ndi chromosome yowonjezera.
Kodi Syndrome Imatha Kukhala Cholowa?
Kawirikawiri, matenda otchedwa Down syndrome sayenera "kulandira" koma angaperekedwe kuchokera kwa makolo kupita kwa ana omwe ali ndi trisomy 21 (omwe amachititsa pafupifupi 4 peresenti ya anthu omwe ali ndi matenda a Down syndrome.) Pafupifupi gawo limodzi mwa atatu mwa anthu omwe ali ndi transrisation trisomy 21, trisomy (ma chromosome awiri a 21 komanso ma chromosome ochuluka 21 omwe amapezeka ku chromosome ina) amachokera kwa kholo. Kuopsa kwa wina amene ali ndi matenda a trisomy 21 kumapangitsa mwanayo kukhala pafupifupi 10 mpaka 15 peresenti kwa amayi ndi atatu peresenti kwa amuna.
Popeza kutumiza kwa trisomy 21 kumangokhala pafupifupi anthu anayi pa anthu 100 alionse omwe ali ndi matenda a Down syndrome, osachepera 1 peresenti ya milandu akhoza kuonedwa ngati choloŵa chawo.
Ngati mwana kapena wamkulu yemwe ali ndi matenda a Down syndrome atenga mimba, chiopsezo cha Down syndrome kapena zina zolepheretsa mwanayo ali pakati pa 35 ndi 50 peresenti. Popeza anthu ambiri omwe ali ndi matenda a Down syndrome amatha kukhala ndi moyo wapamwamba kwambiri, ndipo amakhala ndi chikondi komanso maubwenzi monga omwe alibe matenda a Down syndrome, izi ndizoopsa zomwe ziyenera kuyeza poyerekeza ndi ubwino wa makolowo. Pafupifupi 50 peresenti ya amayi omwe ali ndi Down syndrome amatha kutenga mimba.
Zowopsa
Makolo ambiri omwe ali ndi mwana ndi matenda a Down syndrome alibe zidziwitso zoopsa. Ndikofunika kudziwa kuti, mpaka lero, palibe moyo wamoyo kapena zifukwa za chilengedwe cha Down syndrome . Mwa kuyankhula kwina, kupatulapo kuwonjezeka kwa msinkhu wa amayi (ndipo amayi ambiri omwe ali ndi ana omwe ali ndi Down syndrome ali aang'ono) palibe chomwe chingathandize kudziwiratu kapena kupeŵa kukhala ndi mwana ndi matenda a Down syndrome.
Matenda a Amayi ndi a Down Syndrome
Ngakhale kuti zovuta zitha kuchitika kwa anthu a msinkhu uliwonse, pali mgwirizano pakati pa msinkhu wa amayi ndi mwayi wokhala ndi mwana yemwe ali ndi trisomy. Chiyanjano ndi chabe sayansi ya chiyanjano. Chiyanjano si chifukwa. Izi ndi mfundo yofunika, chifukwa anthu nthawi zambiri amakhala ndi chikhulupiriro cholakwika chakuti zaka za amayi zimayambitsa Down syndrome. Izi si zoona. Sitikudziwa chomwe chimachititsa kuti zizindikiro zichitike. Timadziwa kuti pamene amayi akula, chiopsezo chokhala ndi mimba ndi kuwonjezeka kwa trisomy.
Ngakhale pali kusiyana pakati pa msinkhu wa amayi ndi zochitika zapadera, ana ambiri omwe ali ndi Down syndrome amabadwira amayi omwe ali ndi zaka zoposa 35. Izi ndi chifukwa chakuti pali amayi ambiri omwe ali ndi makanda. Ndipotu, 80 peresenti ya ana obadwa ndi matenda a Down syndrome amabadwira kwa amayi osakwana 35 ndipo a zaka zapakati pa mayi wa mwana yemwe ali ndi Down syndrome ndi zaka 28. Kwachidziwikire, mwayi wa mkazi wosapitirira zaka 30 kubereka mwana wokhala ndi Down syndrome ndi wosachepera 1: 1000. Vuto limakula pamene mkazi akula, ndipo amakhala ndi pafupifupi 1: 112 ali ndi zaka 40. Komabe, izi ndi zosachepera 1 peresenti ya amayi amene amatenga mimba ali ndi zaka 40.
Ndondomeko yoyerekeza za msinkhu wamayi ku matenda a Down syndrome alipo, koma nkofunika kuchenjeza akazi asanayang'ane pa tchatichi. Onetsetsani kukumbukira kuti amayi ambiri omwe amakhala ndi pakati pa zaka 35 ali ndi ana opanda matenda a Down syndrome.
Azimayi ena opitirira zaka 35 (kapena ali ndi zifukwa zina) angasankhe kukhala ndi amniocentesis kuti awonetsere matenda a Down syndrome kapena mayesero ena oyembekezera. Zosankha ngati izi ndizovuta kapena ayi, ndipo ziyenera kupangidwa ndi kuthandizidwa ndi uphungu. American College of Obstetrics ndi Gynecology amalimbikitsa kuti amayi onse aperekedwe kuyezetsa matenda a Down syndrome. Azimayi ena amasankha kuti ayesedwe kuti athe kutsimikiziridwa komanso athe kukonzekera, pomwe pali zifukwa zomveka zomwe amai amasankhira zoyezetsa.
Ukalamba wa Paternal ndi Down Syndrome
Zikuoneka kuti chromosome yowonjezera mu Down syndrome imachokera kwa amayi nthawi zambiri komanso kuchokera kwa bambo (umuna) peresenti yokha peresenti ya nthawiyo. Pamene kukula kwa msinkhu kumayenderana ndi chiwopsezo chotchedwa Down syndrome, zomwezo sizowona pa kukula kwa msinkhu wa abambo chifukwa chakuti mazira amakula, koma umuna umapangidwira nthawi zonse. Komabe, pali zochitika zamtundu wina osati matenda a Down syndrome omwe akugwirizana ndi zaka zapamwamba za abambo, monga achondroplasia (dwarfism) ndi Marfan syndrome.
Kafukufuku ndi Tsogolo
Ndi nkhani ya Human Genome Project ndi gene generapy makolo afunsa funso labwino kwambiri: "Chifukwa chiyani geni singagwiritsidwe ntchito kukonzetsa chibadwa chachibadwa mu Down syndrome?" Mwamwayi, kumvetsa kwathu za majiniko sikudalipobe. Kodi mankhwalawa angathandize bwanji posachedwapa, akugwira ntchito limodzi ndi zosawerengeka za jini. Mkhalidwe umene umayambitsidwa ndi mitundu yambiri ya jini, sizingatheke kuti chromosome yonse ikhale yovuta kuchiza ndi matenda a jini. Ochita kafukufuku akuyang'ana zomwe zingatheke ndi epigenetic engineering-epigenetics ndi munda womwe umayang'ana mafotokozedwe (zachipatala) za majini osati ma jini okha.
Izi zati, oyang'anira ana obadwa ndi matenda a Down syndrome adakula kwambiri zaka makumi angapo zapitazi.
Pansi
Chofunika kwambiri ndikuti timadziwa kuti pali mgwirizano kapena mgwirizano pakati pa msinkhu wa amayi ndi chiopsezo chokhala ndi mwana yemwe ali ndi trisomy monga matenda a Down, koma palibe amene amadziwa chifukwa chake cha matenda.
Zotsatira:
Dekker, A., De Deyn, P., ndi M. Rots. Epigenetics: Chinthu Chosalephereka Chochepetsa Kufooka kwa Kuphunzira ndi Kukumbukira ku Down Syndrome. Maphunziro a zokhudzana ndi ubongo ndi zokhudzana ndi chikhalidwe . 2914. 45: 72-84.
Mentis, A., Epigenomic Engineering kwa Down Synrome. Maphunziro a zokhudzana ndi ubongo ndi zokhudzana ndi chikhalidwe . 2016. 71: 323-327.