Helsmoortel-van der Aa syndrome (HVDAS) is considered an exceptionally rare neurodevelopmental disorder, with a point prevalence of about 1–2/100,000, first reported by Helsmoortel and Van der Aa in 2014 (Helsmoortel et al. 2014). The syndrome presents several clinical manifestations, among which intellectual disability, autism spectrum disorder (ASD), developmental delay, hypotonia, visual difficulties (such as cortical visual impairment, strabismus, hypermetropia, etc.), congenital heart disease (e.g., atrial septal defect), and gastrointestinal problems are the most common characteristics. Van Dijck et al. identified 78 patients from 16 countries with likely mutated ADNP gene (a gene relevant to the syndrome) from a worldwide cohort. They reported that the age range of the affected individuals was between 1 and 40 years, with an average age of 8 years and 2 months (Van Dijck et al. 2019). It is estimated that at least 0.17% of ASD patients possess ANDP gene mutations (Pescosolido et al. 2014) (Figs. 1 and 2).