Sizing the repeat in all available family members with gene specific repeat primed PCR.

Alleles were sized by gene specific repeat primed PCR. As expansions containing over 300 repeated units cannot be reliably sized using this technique, we indicated these alleles as “>300”. Subject A.II.4 is marked with an asterisk as she is mosaic for a 134-bp deletion taking away the entire CGG repeat in combination with a largely expanded allele, and this in addition to a normal sized allele.