PTCHD1 and Neurodevelopmental delay: Although disrupting variants in PTCHD1 are highly penetrant (Chaudhry et al., 2015), we found that the Pro32Leu variant has also been detected in the patient's uncle who has not been diagnosed with NDD, suggesting a variable penetrance in this family, the presence of secondary genetic/nongenetic events that would compensate the impact of the PTCHD1 Pro32Leu variant, or the possibility that it might be unrelated to the disease.