GREB1L (GREB1 like retinoic acid receptor coactivator) functions as a critical regulator of early organ development, particularly in the genitourinary and auditory systems. The gene acts as a co-activator of retinoic acid receptors and is androgen-regulated, playing essential roles in cellular differentiation, morphogenesis, and homeostasis 1. GREB1L shows high expression in developing and postnatal kidneys, with particularly strong staining in proximal tubules throughout development and varying expression patterns in distal tubules and glomeruli across developmental stages 2. The protein is essential for proper kidney and uterine development, with loss-of-function leading to severe developmental anomalies 3. Pathogenic variants in GREB1L are associated with multiple congenital anomalies including Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, renal hypodysplasia/aplasia, and autosomal dominant sensorineural hearing loss 34. Recent evidence suggests GREB1L may also contribute to complex congenital heart disease 5. The gene exhibits autosomal dominant inheritance with incomplete penetrance and variable expressivity, characteristic of neurocristopathies 4. GREB1L variants have been identified in both familial and sporadic cases, with over 127 individuals and 51 unique pathogenic variants documented, highlighting its clinical significance in developmental disorders 5.