It is also intriguing that in our study a variant in HAP was found, whereas in similar series heterozygous variants in huntingtin (HTT) have been described (Lopes et al. 2016; Rodan et al. 2016), further reinforcing the links between Huntington’s disease and Rett syndrome (Roux et al. 2012). The gene discussed is HTT; the disease is Huntington disease.