BRPS is characterised by speech delay, intellectual disability, behavioural anomalies, feeding difficulty, hypotonia, dysmorphism, strabismus and epilepsy (Wang et al., 2022); the patient’s severe feeding problems, hypotonia and global developmental failure map precisely onto this phenotype, establishing ASXL3 loss-of-function as the primary pathogenic driver. Here, ASXL3 is linked to severe feeding difficulties-failure to thrive-microcephaly due to ASXL3 deficiency syndrome.