Witteveen-Kolk Syndrome: Two Patients With Craniofacial Features and Novel SIN3A Variants.

Witteveen-Kolk syndrome (WKS) is a rare autosomal dominant neurodevelopmental disorder caused by pathogenic SIN3A variants, with diagnosis complicated by variable physical findings. We describe two unrelated patients with de novo SIN3A variants identified through trio whole exome sequencing, expanding the phenotype of WKS. Patient 1, a 16-year-old female, presented with bilateral cleft lip and palate, retained primary teeth, and horseshoe kidney: findings not previously reported in WKS. Patient 2, a 5-year-old male, exhibited macrocephaly and obesity, also novel to the WKS phenotype. These findings broaden the recognized clinical spectrum of WKS, supporting earlier and accurate diagnosis, and improved genetic counseling.