▁and ▁reduced ▁T 4 ▁( rat io ▁of ▁T 3 / T 4 ▁is ▁about ▁double ▁its ▁normal ▁value ). ▁Normal ▁looking ▁at ▁birth ▁and ▁for ▁the ▁first ▁few ▁years , ▁hyp ot onic ▁( f lo ppy ), ▁in ▁particular ▁difficulty ▁to ▁hold ▁the ▁head , ▁possibly ▁difficulty ▁to ▁th rive , ▁possibly ▁with ▁delayed ▁my el ination ▁( if ▁so , ▁some ▁cases ▁are ▁reported ▁with ▁an ▁M RI ▁pattern ▁similar ▁to ▁Pel iz ae us – Mer z bach er ▁disease , ▁known ▁as ▁P MD ), ▁possibly ▁with ▁decre ased ▁mit och ond rial ▁en zym e ▁activities , ▁possibly ▁with ▁fl uct u ating ▁la ct ate ▁level . ▁Pat ients ▁have ▁an ▁alert ▁face , ▁a ▁limited ▁I Q , ▁patients ▁may ▁never ▁talk / walk , ▁ 5 0 % ▁need ▁feed ing ▁t ube , ▁patients ▁have ▁a ▁normal ▁life ▁span . ▁This ▁disease ▁can ▁be ▁ruled ▁out ▁with ▁a ▁simple ▁T SH / T 4 / T 3 ▁thy roid ▁test . ▁ ▁Model ▁organ isms ▁ ▁M ice ▁ ▁A ▁conditional ▁knock out ▁mouse ▁line , ▁called ▁Sl c 1 6 a 2 tm 1 a ( K O MP ) W t si ▁was ▁generated ▁as ▁part ▁of ▁the ▁International ▁Kno ck out ▁Mouse ▁Cons ort ium ▁program — a ▁high - through put ▁mut agen esis ▁project ▁to ▁generate ▁and ▁dist ribute ▁animal ▁models ▁of ▁disease ▁to ▁interested ▁scient ists . ▁ ▁Male ▁and ▁female ▁animals ▁under w ent ▁a ▁standard