Aspecific mutation in a certain animal leads to abnormal development of the heart and kidney, resulting in miscarriage. why did this happen?

In molecular biology and genetics, mutations are defined as changes in a genomic sequence and the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can also be defined as spontaneous changes in the cell. Generally, mutations are caused by radiation, viruses, transposons and mutagenic chemicals.

Transposon is a segment of DNA that is capable of inserting copies of itself into other DNA sites within the same cell.