What would happen if the nucleotide sequence of a gene got mixed up?

If this gene codes for a protein, a change in the sequence of the gene would subsequently change the sequence of amino acids of the protein. This would most probably affect the function of the protein due to subsequent changes in the conformation (that is affected by the interactions between the among acids – and their functional groups)

halogen, any of the six nonmetallic elements that constitute group 17 (group viia) of the periodic table. the halogen elements are fluorine (f), chlorine (cl), bromine (br), iodine (i), astatine (at), and tennessine (ts).