使用分割避免表格中出现异常长的空间

Question

抱歉再次上传此内容。当我拆分第一列时，第二列的输出中有很多空格。有什么方法可以消除它吗？这是我的 MWE。我想消除图片中显示的空格。

[![enter image description here][1]][1]\documentclass[12pt,a4paper,oneside]{book}
\usepackage{lmodern}
\usepackage{titling}
\usepackage{setspace}\doublespacing
\usepackage{float}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amsmath,amssymb,amsthm}
\usepackage{thmtools}
\usepackage{pdflscape}
\usepackage{longtable}
\usepackage{rotating}
\usepackage{afterpage}
\usepackage{booktabs}
 \newcommand{\mysplit}[1]{%
  \begin{tabular}{@{}c@{}@{}@{}}   %% removed [t]
  #1
   \end{tabular}
    }

\begin{longtable}{lp{10cm}} 
    \caption{Candidate Genes}\\
    \toprule
    Candidate Gene & Gene function\\
    \midrule
    \endfirsthead 
    \toprule
    Candidate Gene & Gene function\\
    \midrule
    \endhead
    \mysplit{XXXXX\\ XXXXX\\ XXXXX\\ XXXXX\\ XXXXX\\ } & Functions as cell adhesion molecules and receptors in the CNS. Mediate neurotransmitter release by linking Calcium channels to synaptic vesicle exocytosis. Disruption associated with ASD characterised by seizures and communication deficits \\ 
        \mysplit{XXXXXXXXXXX\\ XXXXX\\ XXXXX} & interact as ligands with neurexins expressed in presynaptic neurons. Clinical phenotype is heterogeneous, and mutation carrier undergo regression at disease onset, characterised by loss of acquired social and verbal milestones\\ 
        XXXXXXXXXXX,   & A transcriptional repressor that binds to methylated CpG dinucleotides \\ 
        XXXXXXXXXXX,  & Necessary for proper development of brainstem, cerebellum, inner ear  \\ 
        XXXXXXXXXXX,  &  A tumour suppressor gene influencing G1 cell cycle arrest and apoptosis.  \\ 
        XXXXXXXXXXX, &  implicated in patterns formation during development\\ 
        XXXXXXXXXXX, & One part of 13 subunit ligand gated chloride channel\\ 
        XXXXXXXXXXX, &  Instrumental in cell adhesion as well as cell surface-mediated signalling.\\ 
        XXXXXXXXXXX,  & Pleiotropic receptor with tyrosine kinase activity\\ 
        XXXXXXXXXXX, &  G-protein coupled receptor that binds to Oxytocin \\
        XXXXXXXXXXX, & Large secreted extracellular matrix protein\\
        XXXXXXXXXXX, &  Integral membrane protein\\
    \\\bottomrule
    \end{longtable}
    \end{document}