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. Author manuscript; available in PMC: 2021 Sep 15.
Published in final edited form as: Biol Psychiatry. 2020 Apr 2;88(6):480–487. doi: 10.1016/j.biopsych.2020.03.013

Figure 1. Sex-specific liability thresholds and the expected ASD liability under the "female protective effect" (FPE).

Figure 1

The expected ASD liability under the "female protective effect" (FPE). Example: An individual has ASD and, hypothetically, he has 10 sisters (left, circles) and 10 brothers (right, squares). Under FPE, only the sisters with very high genetic liability will be diagnosed with ASD (1). For the brothers, there will be more ASD diagnosed cases (2), in this example a 3:1 male-to-female-ratio. In the next generation (not shown in the pedigree), since it is more likely that un-diagnosed sisters carry a moderate-to-high genetic liability, the relative risk of ASD among offspring to the un-diagnosed siblings is expected to be higher among those to the sisters than those to the brothers.