\begin{tabular}{|l|l|}
\hline Q.20 & $\begin{array}{l}\text { Fabry disease in humans is a X-linked disease. The probability (in percentage) for } \\
\text { a phenotypically normal father and a carrier mother to have a son with Fabry } \\
\text { disease is }\end{array}$ \\
\hline & \\
\hline
\end{tabular}