tokens: Most ( 58 / 71 , 82 % ) mutations were frameshift and nonsense mutations that are predicted to cause truncation of the A - T protein ; the less common mutation types were missense ( 9 / 71 , 13 % ) , splicing ( 3 / 71 , 4 % ) and one in - frame deletion , 2546 3 ( 1 / 71 , 1 % ) .