Expanding the Phenotype of NRROS-Related SENEBAC Syndrome.

Abstract

Biallelic variants in NRROS are associated with the rare entity of seizures, early-onset, with neurodegeneration and brain calcification (SENEBAC). Here, we report a novel loss of function variant c.720G>A, p.(Trp240*) in a patient with the clinical presentation of developmental regression, refractory seizures, and intracranial calcification. The notable clinical features included normal early development followed by regression of milestones, dysmorphism, microcephaly, refractory seizures, absent deep tendon reflexes, and hypotonia. Neuroimaging features included cerebral atrophy, thin corpus callosum, and white matter calcifications. The phenotype observed in the current report overlaps strongly with the reported phenotype in literature; however, areflexia and dysmorphic features have not been reported before with this entity. A total of 11 individuals have been reported to date. Here, we present a detailed description of the phenotype in an Indian child, expanding the clinical and molecular spectrum of NRROS-related syndrome.