[X-linked intellectual disability syndrome with macrocephaly due to BRWD3 gene deletion]

Pathogenic variants in BRWD3 gene have been described as a rare cause of syndromic X-linked intellectual disability. Its phenotype shows neurodevelopmental delay with intellectual disability in all reported patients, facial dysmorphic features, macrocephaly, overgrowth and obesity. The great majority of cases yield point variants in the gene, only three large deletions including only the BRWD3 gene have been reported. The BRWD3 protein is an epigenetic reader that regulates chromatin remodeling. We report a boy with a compatible phenotype and a deletion including only this gene.

Boy, without family and perinatal pathological background, with neurodevelopmental delay: psychomotor delay, speech delay and intellectual disability, macrocephaly (p > 99) and obesity. Phenotype with facial dysmorphic features: wide forehead, deep set eyes, bulbous nose, prominent ears and pointed chin. The array-CGH analysis showed a 586 kb deletion at Xq21.1 including only one gene with associated disorder, BRWD3. Afterwards, the deletion was also identified in his asymptomatic mother and sister.

Our patient confirms that the haploinsufficiency due to BRWD3 deletion is a causal genetic mechanism of the BRWD3-related syndromic X-linked intellectual disability. It is important to recognize the phenotype for the diagnosis and follow up of the patients, and also to carry out the family genetic analysis in order to identify and give genetic counselling to the women who also have the genetic defect, because the majority of them are asymptomatic, as the mother and sister of our patient.