Overview of repeats
Only one patient has been discovered who had two repeat expansion in the exon 1 of the ZIC3 gene which was responsible for developing X-linked VACTERL syndrome. The patient with the mutation died an hour after birth. It was later determined that the repeat length expanded from 10 to 12 repeats of alanine coded by GCC repeat. None of the 336 controls nor the mother had an expansion in the locus (Wessels et al., 2010).