MDD is Xlnie.kd- We ownk reh omm is a ecrirar dbsea on almify tris,yoh suedpprto yb lab eist.ngt utB reh mom sha 2 X moh,moscoers lyno noe of ichwh si edtau.tm eehrT si on way ot nkow iwhhc her uhtgedra uvlelaenty eceivrse and epsesesxr by ehr hoenyeppt .e(i if ehs si a earrric ro .no)t uJts abcseue hre CK si alrnmo dn’oest anem hse n’sit a taecrir–erh ypnpteeho of eht ldeX-kin crrriae sepddne on tncaatnXi.ivoi-
I do'nt utaddrnnse hsti qnutsei.o yTeh tqaeue rriettsacusr-a ot eanm facefedt yb teh .lleeal eW oknw reh rthome si a aircrre abscuee esh sah ltdaveee .KC tTha sname hte epntiat ash a 50% cachen to be a rrreaic ecsni 'eshs ee.lfam daonRm tonc-naaiitXvi otns'ed aetmtr ehnw tnigkal btoau racirer tutsas uaesbec hotb lelesla hvea a nacehc ot teg sdsaep .no daRonm X tvoiitcianna is ynlo anortptmi ofr rigndmentei wtehhre she lwli eoedplv o.ytsmpms
I esgus ihst si hwy teh oqneuits swa nwrhot ?tou sneUsl 'Im simsnig snhimteo.g
Wyh is eht sewnar rcrirea usstta ok?uwnnn hWy 'cnat eth htemro be ouzhooyg?ms ecnseDuhn si X iednlk esiersecv.
This probably has to do with Barr Bodies (FA 2021, pg 61). To paraphrase FA, penetrance and severity of diseases in XX individuals can be impacted. DMD is included in their list.
Her mom has high CK because her X inactivation is likely imbalanced to have more mutated X expressed. But note that a high CK does not equal full-blown Duchennes. It's similar to Hemophilia--women can have increased bleeding but not full hemophilia because of this phenomenon.
Her mother has some Duchenne phenotype, but we could just as easily see no phenotype in a carrier.
Further, if this woman is a carrier, her child has a 25% chance of developing DMD (50% chance of a boy, 50% of the bad X).
This woman likely has a 50% chance of being a carrier, she doesn't have DMD based on her CK and age and gender.