Biallelic Variant in NRDC Gene in Two Siblings With Developmental Delay and Seizures.

We report a biallelic likely pathogenic variant in the NRDC gene in two Iranian siblings with developmental delay, microcephaly, hypotonia, seizures, and absent speech. Exome sequencing (ES) identified a frameshift deletion in exon 15 of NRDC (NM_001101662.2): c.1702_1703del (p.Met568Valfs*2), confirmed to segregate with disease in the family. This is the second report implicating biallelic NRDC gene variants in neurodevelopmental disorders. Our findings expand the phenotypic spectrum and support a potential role for NRDC in severe neurodevelopmental delay.