Illustration of the non-Mendelian representation of the smaller repeat allele in the proband by repeat length size difference in the parent for the cohorts total (A), NGC trios (B), MSSNG trios (C), and MSSNG quads (D). Although the representation of both the smaller and larger parental allele appeared in equilibrium at lower differences, there was an exponential increase in representation of the smaller allele from five repeat units onward. A final plateau of ∼90% in favor of the shorter allele was reached by a difference of about 15 CGG units. This effect is further illustrated by the ratio of the smaller versus larger repeat allele in Supplemental Figure S2.
