A nucleic acid construct comprising a genetic engineered heterogeneous nuclear ribonucleoprotein (hnRNP) A1 gene is provided. A transgenic mouse in which the expression of hnRNP A1 gene has been disrupted is also provided. The mouse is useful for studying the role of hnRNP A1 gene in normal and disease states of a developmental disorder and muscular diseases. Therefore, a method of screening a compound for potential use in prevention and/or treatment of developmental disorder and muscular diseases is further provided.