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=== Mutacións da helicase ATRX ===
TheO xene ''[[ATRX]]'' genecodifica encodesa thehelicase dependente do ATP-dependent helicase, ATRX (alsotamén known aschamada XH2 ande XNP) ofda thefamilia SNF2do subgroupsubgrupo familySNF2, thatque isse thoughtcre toé beresponsable responsiblede forfunci´ñons functionscomo sucha asremodelación chromatind remodelingcromatina, gene[[regulación regulationxénica]], ande DNA[[metilación methylationdo ADN]].<ref name="ropers">{{cite journal |author=Ropers HH, Hamel BC |title=X-linked mental retardation |journal=Nat. Rev. Genet. |volume=6 |issue=1 |pages=46–57 |date=January 2005 |pmid=15630421 |doi=10.1038/nrg1501 |url=}}</ref><ref name="gibbons">{{cite journal |author=Gibbons RJ, Picketts DJ, Villard L, Higgs DR |title=Mutations in a putative global transcriptional regulator cause X-linked mental retardation with alpha-thalassemia ATR-X syndrome |journal=Cell |volume=80 |issue=6 |pages=837–45 |date=March 1995 |pmid=7697714 |doi= 10.1016/0092-8674(95)90287-2|url=}}</ref><ref name="nextprot">Nextrprot Online Protein Database. [http://www.nextprot.org/db/entry/NX_P46100 " ATRX-Transcriptional regulator ATRX."], Retrieved on 12 November 2012.</ref><ref name="picketts">{{cite journal |author=Picketts DJ, Higgs DR, Bachoo S, Blake DJ, Quarrell OW, Gibbons RJ |title=ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome |journal=Hum. Mol. Genet. |volume=5 |issue=12 |pages=1899–907 |date=December 1996 |pmid=8968741 |doi= 10.1093/hmg/5.12.1899|url=}}</ref> TheseEstas functionsfuncións assistaxudan ina preventionprevir ofa apoptosis[[apoptose]], resultingque inregula corticalo sizetamaño regulation,do ascórtex wellcerebral, ase acontribúe contributioná tosupervivencia thede survivalestruturas ofdo hippocampalhipocampo ande cortical structurescorticais, affectingque memoryafectan andá learning[[memoria]] e [[aprendizaxe]].<ref name="ropers" /> ThisEsta helicase isestá locatedlocalizada onno the[[cromosoma X chromosome]] (Xq13.1-q21.1), inna theheterocromatina pericentromericpericentromérica heterochromatine andúnese binds toá [[Heterochromatinproteína proteinheterocromatínica 1]] (HP1).<ref name="ropers" /><ref name="nextprot" /> Studies have shown that ATRX plays a role in rDNA methylation and is essential for embyonic development.<ref name="gibbons2006">{{cite journal |author=Gibbons R |title=Alpha thalassaemia-mental retardation, X linked |journal=Orphanet J Rare Dis |volume=1 |issue= |pages=15 |year=2006 |pmid=16722615 |pmc=1464382 |doi=10.1186/1750-1172-1-15 |url=}}</ref> MutationsAtropáronse havemutacións beenna found throughout theproteína ''ATRX'' protein, withe overo 90% ofdelas themestán beingasociadas locatedcon indominios the[[dedo zincde fingercinc]] ande helicase domains.<ref name="pagon">{{cite journal |author=Pagon RA, Bird TD, Dolan CR, Stephens K, Adam MP, Stevenson RE |title= Alpha-Thalassemia X-Linked Intellectual Disability Syndrome|journal= |volume= |issue= |pages= |year= 1993|pmid=20301622 |doi= |url=}}</ref> MutationsAs ofmutacións da ATRX canpoden resultcausar inatraso X-linked-alpha-thalassaemia-mental retardationcon alfa-talasemia ligada ao X ([[síndrome ATR-X syndrome]]).<ref name="ropers" />
VariousVarios typestipos ofde mutationsmutacións found inda ATRX haveestán beenasociados foundá to be associated withsíndrome ATR-X, includingincluíndo mostmáis commonlyfrecuentemente single-base[[mutación missensesen mutations,sentido|mutacións assen wellsentido]] asdunha nonsensesoa base, frameshift,e mutacións sen sentido por corremento da andpauta deletione mutations[[deleción]]s.<ref name="picketts" /> As características Characteristicsda ofsíndrome ATR-X includeinclúen: microcephalymicrocefalia, skeletalanormalidades andfaciais faciale abnormalitiesesqueléticas, atraso mental retardation, genitalanormalidades abnormalitiesxenitais, seizuresepilepsia, limiteduso languagee usehabilidade andlingüística abilitylimitada, ande alphaalfa-thalassemiatalasemia.<ref name="ropers" /><ref name="gibbons2006" /><ref name="gibbons1995">{{cite journal |author=Gibbons RJ, Picketts DJ, Villard L, Higgs DR |title=Mutations in a putative global transcriptional regulator cause X-linked mental retardation with alpha-thalassemia (ATR-X syndrome) |journal=Cell |volume=80 |issue=6 |pages=837–45 |date=March 1995 |pmid=7697714 |doi= 10.1016/0092-8674(95)90287-2|url=}}</ref> TheO phenotypefenotipo seenda insíndrome ATR-X suggestssuxire thatque thea mutationmutación ofdo xene ATRX genecausa a causesregulación theá downregulationbaixa ofda gene[[expresión expressionxénica]], suchcomo aspor theexemplo alpha-globinnos genesxenes da alfa-globina.<ref name="gibbons1995" /> ItAínda isnon stillse unknownsabe whatque causescausa thea expressionexpresión ofdas thevariadas variouscaracterísticas characteristicsda ofsíndrome ATR-X inen differentdiferentes patientspacientes.<ref name="gibbons2006" />
=== Mutacións puntuais da helicase XPD ===
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