How do I apply an if statement to a large number of variables without having to rewrite the condition. For example, suppose I have a set of variables sex, age, height ... (about 60 variables) and I want to specify the condition 

if sex = . then sex = -99;
if age = . then age = -99;
.
.
.
All 60 variables that are present in the data set. Is there a quick way to do this?

Thanks