Cutis Tricolor-Like Pigmentary Mosaicism in Mowat-Wilson Syndrome: Phenotypic Overlap With Ruggieri-Happle Syndrome.

Cutis tricolor (CT) is a rare pigmentary mosaicism characterized by the coexistence of hyperpigmented and hypopigmented areas on a background of normal skin; its syndromic form, Ruggieri-Happle syndrome (RHS), is associated with neurodevelopmental delay, facial dysmorphism, skeletal abnormalities, and other systemic defects. We report a 16-year-old girl with molecularly confirmed Mowat-Wilson syndrome caused by a de novo pathogenic ZEB2 frameshift variant, who presented with extensive CT-like pigmentary mosaicism and marked phenotypic overlap with RHS. Brain MRI disclosed bilateral microphthalmia, optic nerve hypoplasia, coloboma, a shortened corpus callosum, a brainstem segmentation defect, and inferior vermian hypoplasia. This observation expands the cutaneous phenotype of ZEB2-related disease and suggests possible shared developmental pathways between Mowat-Wilson syndrome and RHS.