A Saudi Girl With Co-occurring CHD1 (Pilarowski-Bjornsson Syndrome) and ASH1L Gene Variants.

Pilarowski-Bjornsson Syndrome (PBS) is a recently identified and rare genetic disorder. PBS is caused by missense variants in the CHD1 gene, a chromatin remodeler and helicase DNA-binding protein. In this report, we present the first case of PBS in Saudi Arabia. The patient exhibits a phenotype and genotype that are consistent with previously reported cases of PBS. Notably, this case is unique due to the coexisting presence of an absent, small, and homeotic disks protein 1 homolog like a histone lysine methyltransferase (ASH1L) variant and developmental dissociation. The ASH1L variant may contribute to the developmental dissociation observed in the patient. Furthermore, since the patient is female, this case contributes to the female-skewed distribution of PBS, although the exact cause of this phenomenon requires further investigation. This report highlights the importance of identifying and characterizing rare genetic disorders such as PBS. Understanding the genetic basis of these disorders can lead to improved diagnosis, treatment, and management strategies. Continued research on the genetic and molecular mechanisms underlying PBS and related disorders is crucial for advancing our knowledge and developing effective therapies.