I have multiline table.
\documentclass[11pt,table,a5paper]{article}
\usepackage[top=2cm, bottom=2cm, outer=2.1cm, inner=1cm,twoside, headsep=26pt]{geometry}
\usepackage{collcell}
\usepackage{longtable}
\usepackage{color}
\usepackage{colortbl}
\begin{document}
\definecolor{textcol}{rgb}{.118, .565, 1.00}
\definecolor{rowcol}{rgb}{.218, .565, 1.00}
\textbf{Antioxidant/Longevity }
~\\
{\renewcommand{\arraystretch}{1.8}\begin{longtable} {|p{2.8cm}|p{4.7cm}|p{1cm}|p{2.1cm}|}
\hline
\rowcolor{textcol}
\textbf{\textcolor{white}{Title1}} &\textbf{\textcolor{white}{Title2}} &\textbf{\textcolor{white}{Title3}} &\textbf{\textcolor{white}{Title4}}\\
\hline
\rowcolor{rowcol}
54880/RET2& -& 1&-\\
\hline
\rowcolor{rowcol}
rs5746136/SOD2& First Line~\\
~\\
Second Line & 1& some text\\
\hline
\end{longtable}}
\end{document}

But output is not multiline. How can i fix this pblm?

