Genitopatellar Syndrome With a Novel Variant in the KAT6B Gene: Supporting Spectrum Delineation.

Genitopatellar syndrome (GPS) and Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) are rare genetic disorders linked to mutations in the Lysine Acetyltransferase 6B (KAT6B) gene, affecting histone acetylation regulation and developmental processes. We present a case of an African American infant with classic GPS features and a novel KAT6B gene mutation (c.4066del, p.Glu1356Argfs*23). The patient exhibited skeletal anomalies, neurologic deficits, and genitourinary abnormalities, consistent with GPS. Genetic analysis revealed a de novo heterozygous pathogenic variant, adding to the growing understanding of KAT6B-related disorders. Reviewing recent literature, we found an increased prevalence of reported cases and novel gene variants, supporting the delineation of GPS and SBBYSS. Furthermore, analysis suggests a preference range within the gene associated with GPS phenotypes, challenging the notion of a spectrum of KAT6B-related disorders. As genetic sequencing advances, continued reporting of cases will inform decisions regarding the classification of these disorders.