While the facial dysmorphism and intellectual disability present in our cohort is similar to previously published patients with ARID1B mutations [4-7], this study broadens the spectrum of ARID1B-associated phenotypes because all our patients presented with plantar fat pads and fetal finger/toe pads and none of our patients have the fifth nail hypoplasia hallmark of CSS. The gene discussed is ARID1B; the disease is Coffin-Siris syndrome.