A novel KDM5C variant corrects a previously erroneous diagnosis.

Over two decades ago, a primigravid female presented with concern for recurrence of an adverse phenotype affecting her three brothers. The three brothers presented with intellectual disability, developmental delay, behavior problems and dysmorphic features. The screening tools available at the time revealed an FGD1 variant present in all three brothers, their mother being a carrier, absent in their unaffected uncle, and absent in the proband herself.