▁▁ ▁D iff icult y ▁fixing ▁the ▁eyes ▁on ▁an ▁object ▁ ▁Face ▁ ▁Fa cial ▁features ▁gradually ▁become ▁co ar ser ▁during ▁child hood ▁ ▁Mus cul os ke let al ▁system ▁▁ ▁Hyp ot onia ▁ ▁Plan ov alg us ▁ ▁Cont ract ures ▁in ▁el bow ▁joint s ▁ ▁Inter phal ange al ▁joint ▁hyper m ob ility ▁▁ ▁Other ▁associated ▁features ▁include ▁hyp ov ent ilation , ▁ob struct ive ▁and ▁central ▁sleep ▁ap nea ▁and ▁d ys aut onom ia . ▁ ▁Gen et ics ▁ ▁This ▁condition ▁is ▁caused ▁by ▁mut ations ▁in ▁the ▁Pro ly l ▁ 4 - h ydro x yl ase , ▁transm emb rane ▁( P 4 HT M ) ▁gene . ▁This ▁gene ▁is ▁located ▁on ▁the ▁short ▁arm ▁arm ▁of ▁chrom os ome ▁ 3 ▁( 3 p 2 1 . 3 ). ▁ ▁The ▁inheritance ▁of ▁this ▁condition ▁is ▁aut os om al ▁re cess ive . ▁ ▁Di agn osis ▁ ▁The ▁diagn osis ▁may ▁be ▁sus pected ▁on ▁clin ical ▁grounds . ▁▁ ▁It ▁is ▁made ▁by ▁sequ encing ▁the ▁P 4 HT M ▁gene . ▁ ▁Management ▁ ▁There ▁is ▁presently ▁no ▁cur ative ▁treatment . ▁Management ▁is ▁support ive . ▁ ▁Ep ide mi ology ▁ ▁The ▁pre val ence ▁is ▁not ▁known ▁but ▁this ▁is ▁considered ▁to ▁be ▁a ▁rare ▁disease . ▁Only ▁ 1 2 ▁patients ▁have ▁been ▁reported ▁to ▁date . ▁ ▁History ▁ ▁This ▁condition ▁was ▁first ▁described ▁in ▁ 2